ASTM E2533-21

Standard Guide for Nondestructive Examination of Polymer Matrix Composites Used in Aerospace Applications

SIGNIFICANCE AND USE
5.1 This guide references requirements that are intended to control the quality of NDT data. The purpose of this guide, therefore, is not to establish acceptance criteria and therefore approve composite materials or components for aerospace service.  
5.2 Following the discretion of the cognizant engineering organization, NDT for fracture control of composite and bonded materials should follow additional guidance described in MIL-HDBK-6870, NASA-STD-(I)-5019, or MSFC-RQMT-3479, or a combination thereof, as appropriate (not covered in this guide).  
5.3 Certain procedures referenced in this guide are written so they can be specified on the engineering drawing, specification, purchase order, or contract, for example, Practice E1742/E1742M (Radiography).  
5.4 Acceptance Criteria—Determination about whether a composite material or component meets acceptance criteria and is suitable for aerospace service should be made by the cognizant engineering organization. When examinations are performed in accordance with the referenced documents in this guide, the engineering drawing, specification, purchase order, or contract should indicate the acceptance criteria.  
5.4.1 Accept/reject criteria should consist of a listing of the expected kinds of imperfections and the rejection level for each.  
5.4.2 The classification of the articles under test into zones for various accept/reject criteria should be determined from contractual documents.  
5.4.3 Rejection of Composite Articles—If the type, size, or quantities of defects are found to be outside the allowable limits specified by the drawing, purchase order, or contract, the composite article should be separated from acceptable articles, appropriately identified as discrepant, and submitted for material review by the cognizant engineering organization, and dispositioned as (1) acceptable as is, (2) subject to further rework or repair to make the materials or component acceptable, or (3) scrapped when required by contractu...
SCOPE
1.1 This guide provides information to help engineers select appropriate nondestructive testing (NDT) methods to characterize aerospace polymer matrix composites (PMCs). This guide does not intend to describe every inspection technology. Rather, emphasis is placed on established NDT methods that have been developed into consensus standards and that are currently used by industry. Specific practices and test methods are not described in detail, but are referenced. The referenced NDT practices and test methods have demonstrated utility in quality assurance of PMCs during process design and optimization, process control, after manufacture inspection, in-service inspection, and health monitoring.  
1.2 This guide does not specify accept-reject criteria and is not intended to be used as a means for approving composite materials or components for service.  
1.3 This guide covers the following established NDT methods as applied to PMCs: Acoustic Emission (AE, Section 7); Computed Tomography (CT, Section 8); Leak Testing (LT, Section 9); Radiographic Testing, Computed Radiography, Digital Radiography, and Radioscopy (RT, CR, DR, RTR, Section 10); Shearography (Section 11); Strain Measurement (Contact Methods, Section 12); Thermography (Section 13); Ultrasonic Testing (UT, Section 14); and Visual Testing (VT, Section 15).  
1.4 The value of this guide consists of the narrative descriptions of general procedures and significance and use sections for established NDT practices and test methods as applied to PMCs. Additional information is provided about the use of currently active standard documents (an emphasis is placed on applicable standard guides, practices, and test methods of ASTM Committee E07 on Nondestructive Testing), geometry and size considerations, safety and hazards considerations, and information about physical reference standards.  
1.5 To ensure proper use of the referenced standard documents, there are recogni...

General Information

• Status: Published
• Publication Date: 31-Jan-2021
• ICS: 49.025.40 - Rubber and plastics
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.10 - Specialized NDT Methods

Relations

• Refers: ASTM E2580-24 - Standard Practice for Ultrasonic Testing of Flat Panel Composites and Sandwich Core Materials Used in Aerospace Applications
• Effective Date: 01-Feb-2024
• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM E1934-99a(2024) - Standard Guide for Examining Electrical and Mechanical Equipment with Infrared Thermography
• Effective Date: 01-Feb-2024
• Refers: ASTM E1742/E1742M-23 - Standard Practice for Radiographic Examination
• Effective Date: 15-Dec-2023
• Refers: ASTM E1255-23 - Standard Practice for Radioscopy
• Effective Date: 01-Dec-2023
• Refers: ASTM E2581-14(2023) - Standard Practice for Shearography of Polymer Matrix Composites and Sandwich Core Materials in Aerospace Applications
• Effective Date: 01-Dec-2023
• Refers: ASTM E1411-23 - Standard Practice for Qualification of Radioscopic Systems
• Effective Date: 01-Dec-2023
• Refers: ASTM D4762-23 - Standard Guide for Testing Polymer Matrix Composite Materials
• Effective Date: 01-Sep-2023
• Refers: ASTM E1237-20 - Standard Guide for Installing Bonded Resistance Strain Gages
• Effective Date: 15-Aug-2020
• Refers: ASTM E664/E664M-15(2020)e1 - Standard Practice for the Measurement of the Apparent Attenuation of Longitudinal Ultrasonic Waves by Immersion Method
• Effective Date: 01-Jul-2020
• Refers: ASTM E1118/E1118M-16(2020) - Standard Practice for Acoustic Emission Examination of Reinforced Thermosetting Resin Pipe (RTRP)
• Effective Date: 01-Jun-2020
• Refers: ASTM E750-15(2020) - Standard Practice for Characterizing Acoustic Emission Instrumentation
• Effective Date: 01-Jun-2020
• Refers: ASTM E251-20a - Standard Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
• Effective Date: 01-Jun-2020
• Refers: ASTM E1419/E1419M-15a(2020) - Standard Practice for Examination of Seamless, Gas-Filled, Pressure Vessels Using Acoustic Emission
• Effective Date: 01-Jun-2020
• Refers: ASTM E251-20 - Standard Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
• Effective Date: 01-May-2020

Overview

ASTM E2533-21 is a comprehensive guide developed by ASTM International for the selection and application of nondestructive examination (NDE), also known as nondestructive testing (NDT), methods for polymer matrix composites (PMCs) in aerospace applications. It is designed to help engineers and quality assurance professionals choose appropriate NDT methods to characterize and verify the integrity of aerospace composites throughout their lifecycle, including process control, manufacturing inspection, in-service maintenance, and health monitoring.

This standard emphasizes the reference of established NDT methods rather than describing each procedure in detail. Also, it does not provide acceptance criteria for composite materials or components but assists users in identifying suitable methods for quality assessment.

Key Topics

• Scope and Purpose

  • Focuses on established NDT methods proven in aerospace industry practice.
  • References existing consensus standards without defining specific accept/reject criteria.
  • Provides guidance for evaluating the quality of NDT data and results.
  • Stresses the importance of recognized NDT specialist involvement.

• NDT Methods for Aerospace PMCs Addressed

  • Acoustic Emission (AE): For locating and monitoring active sources and discontinuities.
  • Computed Tomography (CT): For 3D analysis and cross-sectional imaging of internal structures.
  • Leak Testing (LT): Detection of leaks across pressure differentials in composites.
  • Radiographic Testing (RT), Computed Radiography (CR), Digital Radiography (DR), and Radioscopy (RTR): For detection of subsurface flaws such as porosity, inclusions, or delaminations.
  • Shearography: Suitable for detecting subsurface imperfections using laser interferometry.
  • Strain Measurement: Typically with strain gauges for monitoring deformation.
  • Infrared Thermography: For non-contact defect detection using heat patterns.
  • Ultrasonic Testing (UT): Widely used for detecting delaminations, voids, and thickness variations.
  • Visual Testing (VT): For initial surface-level inspections.

• Significance and Use

  • Highlights quality control of NDT practices, validation using physical reference standards, and proper documentation.
  • Recommends certified and trained NDT personnel in accordance with national/international standards.

• Flaw Detection

  • NDT methods referenced in this guide can detect a wide range of imperfection types, including delaminations, disbonds, cracks, porosity, inclusions, fiber misalignment, and moisture.

Applications

• Aerospace Manufacturing

  • Ensuring structural integrity of flight control surfaces, pressure vessels, and other composite parts.
  • In-process feedback for process optimization and control without damaging components.

• Inspection and Maintenance

  • After-manufacture inspection and ongoing in-service health monitoring to identify damage, aging, or defects.
  • Life cycle management and safety assurance of composite components in operation or storage.

• Design and Quality Assurance

  • Assists engineering organizations in selecting NDT methods referenced in design drawings, procurement contracts, and technical specifications.
  • Supports the classification of test articles and the zoning of acceptance criteria based on performance requirements.

Related Standards

ASTM E2533-21 cross-references numerous standards and guidelines for NDT and composite evaluation, including:

• ASTM standards (e.g., E1742 for radiography, E2580 for ultrasonic testing, E2581 for shearography, E543 for agency qualification)
• International and national certification standards (ISO 9712, NAS 410, ASNT SNT-TC-1A)
• Military and aerospace documents (MIL-HDBK-6870, NASA-STD-(I)-5019, MSFC-RQMT-3479, CMH-17)
• Other relevant guidelines and codes (ASME Boiler and Pressure Vessel Code, Federal and European safety standards)

Practical Value

• Enhances the reliability and safety of polymer matrix composites used in aerospace through appropriate nondestructive evaluation.
• Streamlines the selection of NDT methods by providing a reference framework for industry-accepted practices.
• Supports compliance with aerospace, military, and international standards for quality assurance and personnel certification.
• Facilitates communication between manufacturers, suppliers, and engineering organizations by standardizing NDT procedures for aerospace composites.

Utilizing ASTM E2533-21 supports process consistency, reduces the risk of undetected defects, and bolsters the overall airworthiness and longevity of advanced aerospace composite structures.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2533 − 21
Standard Guide for
Nondestructive Examination of Polymer Matrix Composites
Used in Aerospace Applications
This standard is issued under the fixed designation E2533; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 1.5 To ensure proper use of the referenced standard
documents, there are recognized NDT specialists that are
1.1 Thisguideprovidesinformationtohelpengineersselect
certified in accordance with industry and company NDT
appropriate nondestructive testing (NDT) methods to charac-
specifications. It is recommended that a NDT specialist be a
terize aerospace polymer matrix composites (PMCs). This
part of any composite component design, quality assurance,
guide does not intend to describe every inspection technology.
in-service maintenance, or damage examination.
Rather, emphasis is placed on established NDT methods that
have been developed into consensus standards and that are
1.6 This guide summarizes the application of NDT proce-
currently used by industry. Specific practices and test methods
durestofiber-andfabric-reinforcedpolymericmatrixcompos-
are not described in detail, but are referenced. The referenced
ites. The composites of interest are primarily, but not
NDT practices and test methods have demonstrated utility in
exclusively, limited to those containing high modulus (greater
quality assurance of PMCs during process design and
than 20 GPa (3×10 psi)) fibers. Furthermore, an emphasis is
optimization, process control, after manufacture inspection,
placed on composites with continuous (versus discontinuous)
in-service inspection, and health monitoring.
fiber reinforcement.
1.2 This guide does not specify accept-reject criteria and is
1.7 This guide is applicable to PMCs containing, but not
not intended to be used as a means for approving composite
limited to, bismaleimide, epoxy, phenolic, poly(amide imide),
materials or components for service.
polybenzimidazole, polyester (thermosetting and
1.3 This guide covers the following established NDT meth-
thermoplastic), poly(ether ether ketone), poly(ether imide),
ods as applied to PMCs: Acoustic Emission (AE, Section 7);
polyimide (thermosetting and thermoplastic), poly(phenylene
Computed Tomography (CT, Section 8); Leak Testing (LT,
sulfide), or polysulfone matrices; and alumina, aramid, boron,
Section 9); Radiographic Testing, Computed Radiography,
carbon, glass, quartz, or silicon carbide fibers.
Digital Radiography, and Radioscopy (RT, CR, DR, RTR,
Section 10); Shearography (Section 11); Strain Measurement
NOTE 1—Per the discretion of the cognizant engineering organization,
(Contact Methods, Section 12); Thermography (Section 13);
composite materials not developed and qualified in accordance with the
guidelinesinCMH-17,Volumes1and3shouldhaveanapprovedmaterial
Ultrasonic Testing (UT, Section 14); and Visual Testing (VT,
usage agreement.
Section 15).
1.8 The composite materials considered herein include uni-
1.4 Thevalueofthisguideconsistsofthenarrativedescrip-
axial laminae, cross-ply laminates, angle-ply laminates, and
tions of general procedures and significance and use sections
sandwich constructions. The composite components made
for established NDT practices and test methods as applied to
therefrom include filament-wound pressure vessels, flight con-
PMCs. Additional information is provided about the use of
trol surfaces, and various structural composites.
currently active standard documents (an emphasis is placed on
applicable standard guides, practices, and test methods of
1.9 For current and potential NDT procedures for finding
ASTM Committee E07 on Nondestructive Testing), geometry
indications of discontinuities in the composite overwrap and
andsizeconsiderations,safetyandhazardsconsiderations,and
thin-walled metallic liners in filament-wound pressure vessels,
information about physical reference standards.
also known as composite overwrapped pressure vessels
(COPVs), refer to Guides E2981 and E2982, respectively.
This guide is under the jurisdiction ofASTM Committee E07 on Nondestruc-
tiveTesting and is the direct responsibility of Subcommittee E07.10 on Specialized
1.10 ForasummaryoftheapplicationofdestructiveASTM
NDT Methods.
standard practices and test methods (and other supporting
Current edition approved Feb. 1, 2021. Published March 2021. Originally
ε1 standards)tocontinuous-fiberreinforcedPMCs,refertoGuide
approved in 2009. Last previous edition approved in 2017 as E2533–17 . DOI:
10.1520/E2533-21. D4762.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2533 − 21
1.11 Units—The values stated in SI units are to be regarded E747Practice for Design, Manufacture and Material Group-
as standard. The values given in parentheses after SI units are ing Classification of Wire Image Quality Indicators (IQI)
providedforinformationonlyandarenotconsideredstandard.
Used for Radiology
E750Practice for Characterizing Acoustic Emission Instru-
1.12 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the mentation
responsibility of the user of this standard to establish appro- E976GuideforDeterminingtheReproducibilityofAcoustic
priate safety, health, and environmental practices and deter-
Emission Sensor Response
mine the applicability of regulatory limitations prior to use.
E1000Guide for Radioscopy
1.13 This international standard was developed in accor-
E1001PracticeforDetectionandEvaluationofDiscontinui-
dance with internationally recognized principles on standard-
ties by the Immersed Pulse-Echo Ultrasonic Method
ization established in the Decision on Principles for the
Using Longitudinal Waves
Development of International Standards, Guides and Recom-
E1002Practice for Leaks Using Ultrasonics
mendations issued by the World Trade Organization Technical
E1003Practice for Hydrostatic Leak Testing
Barriers to Trade (TBT) Committee.
E1025Practice for Design, Manufacture, and Material
Grouping Classification of Hole-Type Image Quality In-
2. Referenced Documents
dicators (IQI) Used for Radiography
2.1 ASTM Standards:
E1065/E1065MPractice for Evaluating Characteristics of
D3878Terminology for Composite Materials
Ultrasonic Search Units
D4762Guide for Testing Polymer Matrix Composite Mate-
E1066/E1066MPractice for Ammonia Colorimetric Leak
rials
Testing
E94/E94MGuide for Radiographic Examination Using In-
E1067/E1067MPracticeforAcousticEmissionExamination
dustrial Radiographic Film
of Fiberglass Reinforced Plastic Resin (FRP) Tanks/
E114Practice for Ultrasonic Pulse-Echo Straight-Beam
Vessels
Contact Testing
E1118/E1118MPracticeforAcousticEmissionExamination
E214Practice for Immersed Ultrasonic Testing by the Re-
of Reinforced Thermosetting Resin Pipe (RTRP)
flection Method Using Pulsed Longitudinal Waves (With-
E1211/E1211MPractice for Leak Detection and Location
drawn 2007)
E251Test Methods for Performance Characteristics of Me- Using Surface-Mounted Acoustic Emission Sensors
tallic Bonded Resistance Strain Gages E1213Practice for Minimum Resolvable Temperature Dif-
E317PracticeforEvaluatingPerformanceCharacteristicsof
ference for Thermal Imaging Systems
Ultrasonic Pulse-Echo Testing Instruments and Systems
E1237Guide for Installing Bonded Resistance Strain Gages
without the Use of Electronic Measurement Instruments
E1255Practice for Radioscopy
E427PracticeforTestingforLeaksUsingtheHalogenLeak
E1311Practice for Minimum Detectable Temperature Dif-
Detector Alkali-Ion Diode (Withdrawn 2013)
ference for Thermal Imaging Systems
E432Guide for Selection of a Leak Testing Method
E1316Terminology for Nondestructive Examinations
E493/E493MPractice for Leaks Using the Mass Spectrom-
E1324GuideforMeasuringSomeElectronicCharacteristics
eter Leak Detector in the Inside-Out Testing Mode
of Ultrasonic Testing Instruments
E498/E498MPractice for Leaks Using the Mass Spectrom-
E1411Practice for Qualification of Radioscopic Systems
eterLeakDetectororResidualGasAnalyzerintheTracer
E1419/E1419MPractice for Examination of Seamless, Gas-
Probe Mode
Filled, Pressure Vessels Using Acoustic Emission
E499/E499MPractice for Leaks Using the Mass Spectrom-
E1441Guide for Computed Tomography (CT)
eter Leak Detector in the Detector Probe Mode
E1543PracticeforNoiseEquivalentTemperatureDifference
E515Practice for Leaks Using Bubble EmissionTechniques
of Thermal Imaging Systems
E543Specification forAgencies Performing Nondestructive
E1570Practice for Fan Beam Computed Tomographic (CT)
Testing
Examination
E569/E569MPractice for Acoustic Emission Monitoring of
E1603/E1603MPractice for Leakage Measurement Using
Structures During Controlled Stimulation
E650/E650MGuide for Mounting Piezoelectric Acoustic the Mass Spectrometer Leak Detector or Residual Gas
Emission Sensors
Analyzer in the Hood Mode
E664/E664MPractice for the Measurement of theApparent
E1647Practice for Determining Contrast Sensitivity in Ra-
Attenuation of Longitudinal Ultrasonic Waves by Immer-
diology
sion Method
E1672Guide for Computed Tomography (CT) System Se-
lection
2 E1695Test Method for Measurement of Computed Tomog-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM raphy (CT) System Performance
Standards volume information, refer to the standard’s Document Summary page on
E1742/E1742MPractice for Radiographic Examination
the ASTM website.
3 E1815Test Method for Classification of Film Systems for
The last approved version of this historical standard is referenced on
www.astm.org. Industrial Radiography
E2533 − 21
E1817Practice for Controlling Quality of Radiological Ex- E2736Guide for Digital Detector Array Radiography
amination by Using Representative Quality Indicators E2737Practice for Digital Detector Array Performance
Evaluation and Long-Term Stability
(RQIs)
E1862Practice for Measuring and Compensating for Re- E2981Guide for Nondestructive Examination of Composite
Overwraps in Filament Wound Pressure Vessels Used in
flected Temperature Using Infrared Imaging Radiometers
Aerospace Applications
E1897Practice for Measuring and Compensating for Trans-
E2982Guide for Nondestructive Testing of Thin-Walled
mittance of anAttenuating Medium Using Infrared Imag-
MetallicLinersinFilament-WoundPressureVesselsUsed
ing Radiometers
in Aerospace Applications
E1901Guide for Detection and Evaluation of Discontinui-
F1364Practice for Use of a Calibration Device to Demon-
ties by Contact Pulse-Echo Straight-Beam Ultrasonic
strate the Inspection Capability of an Interferometric
Methods
Laser Imaging Nondestructive Tire Inspection System
E1932Guide for Acoustic Emission Examination of Small
2.2 ASNT Standards and Documents:
Parts
ASNT CP-189Standard for Qualification and Certification
E1933Practice for Measuring and Compensating for Emis-
of Nondestructive Testing Personnel
sivity Using Infrared Imaging Radiometers
SNT-TC-1ARecommended Practice for Personnel Qualifi-
E1934Guide for Examining Electrical and Mechanical
cation and Certification in Nondestructive Testing
Equipment with Infrared Thermography
Leak Testing, Volume 1,Nondestructive Testing Handbook
E1935Test Method for Calibrating and Measuring CT
Nondestructive Testing Handbook, Visual and Optical
Density
Testing, Vol. 8
E2002Practice for Determining Total Image Unsharpness
2.3 ASTM Adjuncts:
and Basic Spatial Resolution in Radiography and Radios-
Curing Press Straining Block (13 Drawings)
copy
2.4 ISO Standard:
E2007Guide for Computed Radiography
ISO 9712Non-destructive Testing—Qualification and Cer-
E2024/E2024MPractice for Atmospheric Leaks Using a
tification of NDT Personnel
Thermal Conductivity Leak Detector
2.5 AIA Standard:
E2033Practice for Radiographic Examination Using Com-
NAS 410Certification & Qualification of Nondestructive
puted Radiography (Photostimulable Luminescence
Test Personnel
Method)
2.6 MIL Documents:
E2076/E2076MPractice for Examination of Fiberglass Re-
CMH-17Composite Materials Handbook, Volume 1. Poly-
inforced Plastic Fan Blades Using Acoustic Emission
mer Matrix Composites, Guidelines For Characterization
E2104Practice for Radiographic Examination of Advanced
Of Structural Materials (formerly MIL-HDBK-17)
Aero and Turbine Materials and Components
CMH-17 Composite Materials Handbook, Volume 3. Poly-
E2191/E2191MPractice for Examination of Gas-Filled
mer Matrix Composites, Materials Usage, Design, and
Filament-Wound Composite Pressure Vessels Using
Analysis (formerly MIL-HDBK-17)
Acoustic Emission
MIL-HDBK-6870Inspection Program Requirements, Non-
E2208Guide for Evaluating Non-Contacting Optical Strain
destructive for Aircraft and Missile Materials and Parts
Measurement Systems
MIL-HDBK-732A Nondestructive Testing Methods of
E2445/E2445MPractice for Performance Evaluation and
Composite Materials—Acoustic Emission
Long-Term Stability of Computed Radiography Systems
MIL-HDBK-728 ⁄5A Radiologic Testing
E2446Practice for Manufacturing Characterization of Com-
MIL-HDBK-733 Nondestructive Testing Methods of Com-
puted Radiography Systems
posite Materials—Radiography
E2580PracticeforUltrasonicTestingofFlatPanelCompos-
MIL-HDBK-731 Nondestructive Testing Methods of Com-
ites and Sandwich Core Materials Used in Aerospace
posite Materials—Thermography
Applications
MIL-HDBK-787Nondestructive Testing Methods of Com-
E2581Practice for Shearography of Polymer Matrix Com-
posite Materials—Ultrasonics
posites and Sandwich Core Materials inAerospaceAppli-
MIL-L-25567DLeak Detection Compound, Oxygen Sys-
cations
tems
E2582Practice for Infrared Flash Thermography of Com-
posite Panels and Repair Patches Used in Aerospace
Applications 4
AvailablefromAmericanSocietyforNondestructiveTesting,P.O.Box28518,
E2597/E2597MPracticeforManufacturingCharacterization 1711 Arlington Lane, Columbus, OH 43228-0518.
Available from ASTM International Headquarters. Order Adjunct No.
of Digital Detector Arrays
ADJf1364.
E2661/E2661MPracticeforAcousticEmissionExamination
Available from International Organization for Standardization (ISO), ISO
of Plate-like and Flat Panel Composite Structures Used in
Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, https://www.iso.org.
Aerospace Applications
Available from Aerospace Industries Association (AIA), 1000 Wilson Blvd.,
E2662Practice for Radiographic Examination of Flat Panel
Suite 1700, Arlington, VA 22209, http://www.aia-aerospace.org.
Composites and Sandwich Core Materials Used in Aero-
Available for Standardization Documents Order Desk, Bldg 4 Section D, 700
space Applications Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
E2533 − 21
2.7 NASA Documents: EN 14784-2, Non-Destructive Testing—Industrial Com-
NASA-STD-(I)-5019Fracture Control Requirements for puted Radiography with Storage Phosphor Imaging
Spaceflight Hardware Plates— Part 2: General Principles forTesting of Metallic
MSFC-RQMT-3479 Fracture Control Requirements for Materials Using X-Rays and Gamma Rays
Composite and Bonded Vehicle and Payload Structures EN 13068-1, Non-Destructive Testing—Radioscopic
2.8 Federal Standards: Testing—Part 1: Quantitative Measurement of Imaging
Properties
NBS Handbook 114General Radiation Safety Installations
Using Nonmedical X-ray and Sealed Gamma Sources up EN 13068-2, Non-Destructive Testing—Radioscopic
Testing—Part2:CheckofLongTermStabilityofImaging
to 10 MeV
Title 10, Code of Federal Regulations (CFR), Part 20, Devices
EN 13068-3, Non-Destructive Testing—Radioscopic
Standards for Protection Against Radiation
Title 21, Code of Federal Regulations (CFR), 1020.40, Testing—Part 3: General Principles of Radioscopic Test-
ing of Metallic Materials by X- and Gamma Rays
Safety Requirements of Cabinet X-ray Systems
Title 29,Code of Federal Regulations (CFR), 1910.96, 2.15 LIA Document:
ANSI, Z136.1-2000, Safe Use of Lasers
Ionizing Radiation (X-rays, RF, etc.)
2.16 BSI Document:
2.9 FDA Standards:
EN 60825-1Safety of Laser Products—Part 1: Equipment
21 CFR 1040.10 Laser Products
Classification, Requirements and User’s Guide
21 CFR 1040.11 Specific Purpose Laser Products
2.10 ASME Standard:
3. Terminology
ASME Boiler and Pressure Vessel Code, Section V, Non-
3.1 Abbreviations—The following abbreviations are ad-
destructive Examination, Article 11, Acoustic Emission
opted in this guide: Acoustic Emission (AE), Computed
Examination of Fiber-Reinforced Plastic Vessels
Radiography (CR), Computed Tomography (CT), Digital Ra-
2.11 CGA Standard:
diography (DR), Leak Testing (LT), Radiographic Testing
Pamphlet C-6.4 Methods for External Visual Inspection of
(RT), Radioscopy (RTR), and Ultrasonic Testing (UT).
Natural Gas Vehicle (NGV) and Hydrogen Gas Vehicle
(HGV) Fuel Containers and Their Installations
3.2 Definitions—Definitions of terms related to NDT of
2.12 NCRP Documents:
aerospacecompositeswhichappearinTerminologyE1316and
NCRP 49Structural Shielding Design and Evaluation for Terminology D3878 should apply to the terms used in this
Medical Use of X-Rays and Gamma Rays of Energies up
guide.
to 10 MeV
3.3 Definitions of Terms Specific to This Standard:
NCRP 51 Radiation Protection Design Guidelines for
3.3.1 aerospace, n—anycomponentthatwillbeinstalledon
0.1–100 MeV Particle Accelerator Facilities
a system that flies.
NCRP 91Recommendation on Limits for Exposures to
3.3.2 cognizant engineering organization, n—the company,
Ionizing Radiation
15 government agency, or other authority responsible for the
2.13 SAE Standard:
design,orenduse,ofthesystemorcomponentforwhichNDT
SAE-ARP 1611, RevisionAQuality Inspection Procedures,
is required.
Composites: Tracer Fluoroscopy and Radiography
3.3.2.1 Discussion—This, in addition to the design
2.14 European Standards:
personnel, may include personnel from engineering, materials
EN 14784-1, Non-Destructive Testing—Industrial Com-
and process engineering, stress analysis, NDT, or quality
puted Radiography with Storage Phosphor Imaging
groups and other, as appropriate.
Plates—Part 1: Classification of Systems
3.3.3 composite material, n—see Terminology D3878.
3.3.4 composite component, n—a finished part containing
Available from National Aeronautics and Space Administration, Technical
composite material(s) that is in its end use application
Standards Program, 300 E. Street SW, Suite 5R30, Washington, D. C. 20546,
https://standards.nasa.gov/documents/nasa. configuration, and which has undergone processing,
Available from National Technical Information Service (NTIS), U. S. Depart-
fabrication, and assembly to the extent specified by the
ment of Commerce, 5285 Port Royal Road, Springfield, VA 22161.
drawing, purchase order, or contract.
Published by the Center for Devices and Radiological Health (CDRH) of the
Food and Drug Administration (FDA), available from Government Printing Office
3.3.5 disbond, n—see Terminology D3878.
Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE,
3.3.6 in-service, n—refers to composite components that
Washington, DC 20401.
Available from American Society of Mechanical Engineers (ASME), ASME havecompletedinitialfabricationandareinuse(orinstorage)
International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
for their intended function.
www.asme.org.
3.3.7 microcrack, n—invisible cracks (< 50 to 100 µm size)
Available from Compressed Gas Association (CGA), 14501 George Carter
Way, Suite 103, Chantilly, VA 20151, http://www.cganet.com.
that are precursors to visible cracks.
Available from NCRP Publications, 7010 Woodmont Ave., Suite 1016,
Bethesda, MD 20814.
15 17
Available from SAE International (SAE), 400 Commonwealth Dr., Available from the Laser Institute of America, 13501 Ingenuity Drive, Suite
Warrendale, PA 15096, http://www.sae.org. 128, Orlando, FL 32826.
16 18
Available from European Committee for Standardization (Electrotechnical), Available from British Standards Institution (BSI), 389 Chiswick High Rd.,
CENELEC Customer service ([e-mail]). London W4 4AL, U.K., http://www.bsigroup.com.
E2533 − 21
3.3.7.1 Discussion—In angle-ply continuous fiber- minations by hardness measurements, visual testing for
reinforced composites, for example, microcracks form prefer- defects, and tapping for void determinations. If the integrity of
entially under tensile loading in the matrix in off-axis plies. thesubassemblywarrantsamorecompleteinspection,thiscan
Sincemostmicrocracksdonotpenetratethereinforcingfibers, be accomplished by using various NDT procedures discussed
microcracks in a cross-plied tape laminate or in a laminate inthisguide.Nondestructivetestscanusuallybemaderapidly.
madefromclothprepregareusuallylimitedtothethicknessof However, nondestructive testing will, in general, add to com-
a single ply. ponentcostandshouldbeusedonlywhenwarrantedoncritical
applications. Also, the extent of NDT on composite parts
3.3.8 reference standards, n—objects that provide a known,
depends on whether the part is a primary structure safety of
reproducible, and repeatable response to a specific stimulus;
flight part, or secondary structure non-safety of flight part.The
may be in the form of hardware or software.
type or class of part is usually defined on the engineering
3.3.9 sandwich construction, n—see Terminology D3878.
drawing. Some of the flaws that can be detected by NDT are
given in Table 1.
4. Summary of Guide
4.3 Other critical defect characteristics not mentioned in
4.1 This guide describes and provides references for the
Table 1 that need to be considered when establishing NDE
practice and utilization of the following established NDT
procedures include defect size, defect shape, defect depth,
procedures as applied to polymeric matrix composites:
defect orientation, fiber volume fraction, resin rich regions,
4.1.1 Acoustic Emission (Section 7).
resin poor regions, cure state, fiber sizing, fiber-matrix
4.1.2 Computed Tomography (X-ray Method) (Section 8).
bonding, crazing (cracking of amorphous matrix resins due to
4.1.3 Leak Testing (Section 9).
exposure to stress or the service environment), residual and
4.1.4 Radiography,ComputedRadiography,DigitalRadiog-
internalstress,degradation(chemicalandphysicalattack),and
raphy with Digital Detector Array Systems, and Radioscopy
impact damage.
(Section 10).
4.1.5 Shearography (Section 11). 4.4 Facility Qualification—Minimum general requirements
4.1.6 Strain Measurement (Strain Gauges) (Section 12). for NDT facilities and personnel qualification are given in
4.1.7 Infrared Thermography (Non-Contact Methods Using SpecificationE543.Thisspecificationcanbeusedasabasisto
Infrared Camera) (Section 13). evaluatetestingorinspectionagencies,orboth,andisintended
4.1.8 Ultrasonic Testing (Section 14). for use for the qualifying or accrediting, or both, of testing or
4.1.9 Visual Testing (Section 15). inspection agencies, public or private.
4.2 NDT Method Selection—Compositecomponentssuchas 4.5 Personnel Certification—NDT personnel should be cer-
laminates, moldings, and subassemblies may be inspected by
tified in accordance with a nationally or internationally recog-
simple procedures consisting of dimensional and tolerance nized practice or standard such asANSI/ASNT-CP-189, SNT-
measurements, weight and density determinations, cure deter-
TC-1A, NAS 410, ISO 9712, or a similar document. The
TABLE 1 Flaws Detected By NDT Procedures
Radiography
Acoustic Computed Leak with DDA; Strain Ultrasonic Visual
Defect Shearography Thermography
Emission Tomography Testing Radiography, Measurement Testing Testing
CR, Radioscopy
Contamination X X X X
Damaged Filaments X X X
Delamination X X X X X X
Density Variation X X X X
Deformation under Load XX
Disbond X X X X X
A
Fiber Debonding X X XX
Fiber Misalignment X X X
Fractures X X X X X X
Inclusions X X X X X
Leaks X X X
Loose or Moving Parts X
B B,C
Microcracks X X XXX
D,E
Moisture X X X
Porosity X X X X X
F
Thickness Variation X X XXX
Undercure X
Volumetric Effects X
Voids X X X X X X
A
Can detect after impact (voids).
B
Depends on opening/size of crack.
C
Depends on angle of beam relative to planar defect and opening.
D
Only in central projection (Radiography, CR).
E
Radioscopic mode (Radiography with DDA).
F
For Radiography, applicable to CR and digitized films only.
E2533 − 21
practiceorstandardusedanditsapplicablerevisionsshouldbe inMIL-HDBK-6870,NASA-STD-(I)-5019,orMSFC-RQMT-
specified in any contractual agreement between the using 3479, or a combination thereof, as appropriate (not covered in
parties.
this guide).
4.6 Personnel Qualification—NDT personnel should be
5.3 Certain procedures referenced in this guide are written
qualified by accepted training programs, applicable on-the-job
so they can be specified on the engineering drawing,
training, or a competent mentor or component manufacturer.
specification,purchaseorder,orcontract,forexample,Practice
Personnel will be only qualified to inspect parts that come
E1742/E1742M (Radiography).
under direct training experience or production.
5.4 Acceptance Criteria—Determination about whether a
4.7 General Equipment and Instrumentation
compositematerialorcomponentmeetsacceptancecriteriaand
Considerations—General equipment and instrumentation con-
is suitable for aerospace service should be made by the
siderations are provided in Specification E543. NDT method
cognizant engineering organization. When examinations are
specific considerations are discussed in the appropriate section
performedinaccordancewiththereferenceddocumentsinthis
of this guide (Sections7–15).
guide, the engineering drawing, specification, purchase order,
4.8 Reference Standards—Physical reference standards
or contract should indicate the acceptance criteria.
simulating target imperfections or discontinuities are used to
5.4.1 Accept/reject criteria should consist of a listing of the
validate NDT results. The use of physical reference standards
expected kinds of imperfections and the rejection level for
also helps to ensure reproducibility and repeatability of mea-
each.
surements. Certified physical reference standards calibrated by
5.4.2 The classification of the articles under test into zones
accepted government or industrial agencies may be used.
for various accept/reject criteria should be determined from
4.9 Extent of Examination—Specific applications may re-
contractual documents.
quire local regions or the entire component to be examined.
5.4.3 Rejection of Composite Articles—If the type, size, or
Examination may be real time or delayed based upon the
quantities of defects are found to be outside the allowable
availability of data. Examination may be direct, or indirect, on
limitsspecifiedbythedrawing,purchaseorder,orcontract,the
site or remote as specified in the contractual agreement or
composite article should be separated from acceptable articles,
established requirements documents.
appropriately identified as discrepant, and submitted for mate-
4.10 Timing of Examination—Examinations should be per-
rial review by the cognizant engineering organization, and
formed in accordance with the contractual agreement or
dispositioned as (1) acceptable as is, (2) subject to further
established requirements documents, and may be performed
rework or repair to make the materials or component
during the life cycle of the article under test.
acceptable, or (3) scrapped when required by contractual
4.11 Type of Examinations—Many different NDT system
documents.
configurations are possible due to the wide range of system
5.4.4 Acceptance criteria and interpretation of result should
componentsavailable.ItisimportantforthepurchaserofNDT
be defined in requirements documents prior to performing the
to understand the capability and limitations of the applicable
examination. Advance agreement should be reached between
configuration. Selection of the NDT procedure and system
the purchaser and supplier regarding the interpretation of the
should be at the discretion of the testing agency unless
results of the examinations. All discontinuities having signals
specified by the purchaser in a contract or requirements
that exceed the rejection level as defined by the process
document (that is, engineering drawing, specifications, etc.).
requirements documents should be rejected unless it is deter-
4.12 A tabular comparison of most of the established NDT
mined from the part drawing that the rejectable discontinuities
procedures discussed in the guide is given inAppendix X1 of
will not remain in the finished part.
Specification E543; namely, acoustic emission, leak testing,
radiography,strainmeasurement,thermography(infrared),and 5.5 Life Cycle Considerations—The referenced NDT prac-
ultrasoundarecovered.Thecomparisonsummarizesproperties tices and test methods have demonstrated utility in quality
sensed or measured, typical discontinuities detected, represen-
assurance of PMCs during the life cycle of the product. The
tativeapplication,applicableASTMstandards,andadvantages
modern NDT paradigm that has evolved and matured over the
and limitations. A similar overview is provided in Table 2.
last twenty–five years has been fully demonstrated to provide
benefits from the application of NDT during: (a) product and
5. Significance and Use
process design and optimization, (b) on-line process control,
(c) after manufacture inspection, (d) in-service inspection, and
5.1 This guide references requirements that are intended to
(e) health monitoring.
control the quality of NDT data. The purpose of this guide,
therefore, is not to establish acceptance criteria and therefore
5.5.1 In-process NDT can be used for feedback process
approve composite materials or components for aerospace
control since all tests are based upon measurements which do
service.
not damage the article under test.
5.5.2 TheapplicabilityofNDTprocedurestoevaluatePMC
5.2 Following the discretion of the cognizant engineering
materialsandcomponentsduringtheirlifecycleissummarized
organization, NDT for fracture control of composite and
bonded materials should follow additional guidance described in Tables 3 and 4.
E2533 − 21
TABLE 2 General Overview of Established NDT Procedures
What Is Seen
NDT Method Applications Advantages Limitations Other Considerations
and Reported?
Acoustic Emission Global monitoring of Remote and continuous The part being inspected The AE technique Inspection tests and
composite structures to monitoring on an entire must be stressed by records transient elastic results are unique to
detect and locate active composite article in real mechanical, load, waves produced by each application and
sources in real time. time is possible. Can pressure, temperature, applied stress or should be conducted
also detect growth of or other stimulus. With resulting stress with expert oversight.
active imperfections or the exception of certain relaxation of the
discontinuities, and imperfections or composite material or
detect and determine the discontinuities that AE component. The
location of discontinuities detects by friction- mechanical waves are
and defects that may be generated AE (for produced as either burst
inaccessible by other example, delamination or continuous AE. AE
NDT procedures. surfaces rubbing), AE- activity, intensity and
inactive (non- severity correlated with
propagating) applied stress yield
imperfections or information on the
discontinuities cannot be degradation within the
detected and structurally article under test.
insignificant
imperfections or
discontinuities may
produce AE. Therefore,
the significance of a
detected AE source
cannot be assessed
unambiguously.
Computed Tomography Detects sub-surface Produces clear cross- Requires access to all A digitized cross- Tooling or part-handling
volumetric imperfections sectional image slices of sides of the article under sectional CT-density map fixtures, or both, may be
or discontinuities. an object. Obtains 3D test. Not very applicable (tomogram) of the article required.
Provides quantitative, imperfection or to the inspection of large under test. Allows full,
volumetric analysis of discontinuity data. areas, or objects with three dimensional CT-
imperfections or Extensive image high (>15) aspect ratios. density maps to be
discontinuities detectable processing capability. obtained for sufficiently
by other NDT small composite parts.
procedures. Also suitable
for measuring geometric
characteristics.
Leak Testing Any composite material Less ambiguous than Test equipment costs Qualitative indications, Different techniques are
or component across liquid penetrant testing; increase as the required for example bubbles, or available for
which a differential more sensitive than AE leak test sensitivity quantitative characterization of large
pressure exists and or UT. increases. measurements, for leaks (with rates as high
-2 3 -1 -1
where through-leakage example, detector as 10 Pa m s (10
3 -1
or in-leakage of product, deflections, that std cm s )) and small
air, water vapor, or other ascertain the presence leaks (rates less than
-5 3 -1 -4
contaminant over the or location, or 10 Pa m s (10 std
3 -1
projected service life are concentration or leak cm s )).
of concern. rate of a leaking fluid.
Radiography, Primarily detects sub- Film and some imaging Requires access to both Projected area and Part may need to be
Computed Radiography, surface imperfections or plates can be cut and sides of the article under density variation of moved to an X-ray lab;
Radiography with Digital discontinuities such as placed almost anywhere test. Accessibility may subsurface imperfections Film RT requires film
Detector Arrays, porosity & inclusions. on the part. Digital need to be evaluated. or discontinuities. storage and disposal of
Radioscopy Planar imperfections or images can be Unable to determine chemicals which can be
discontinuities are processed for additional depth of imperfections or expensive. Digital
detected if the beam is information and discontinuities; techniques (CR, DDA)
directed along the automated defect sometimes possible from are usually faster.
imperfection or recognition. In digital images after Radiation safety. In
discontinuity and the radioscopy, techniques calibration or with radioscopy, radiation
unsharpness is less than using an image additional X-ray safety more problematic
the imperfection or intensifier and DDA can exposures from different if a moving source is
discontinuity opening/ be automated by directions. used, versus movement
size. interfacing with a robot of part.
or part manipulator thus
allowing the potential for
a faster inspection.
5.6 General Geometry and Size Considerations—Part 5.7 Reporting—Reports and records should be specified by
contour, curvature, and surface condition may limit the ability agreement between purchaser and supplier. It is recommended
of certain tests to detect imperfections with the desired that any NDT report or archival record contain information,
accuracy. whenavailable,aboutthematerialtype;methodoffabrication;
E2533 − 21
TABLE 2 Continued
What Is Seen
NDT Method Applications Advantages Limitations Other Considerations
and Reported?
Shearography Detects subsurface Well suited for high Subsurface imperfection An interference pattern Additional equipment is
imperfections or speed, automated or discontinuity should created by subtracting or required to determine
discontinuities or inspection in production be sufficiently large to superimposing images of surface derivative slope
changes in modulus or environments. cause measurable the article under test changes, and thus uses
out-of-plane deformation. surface deformation taken before and after the method as a
under load. Surface loading, thus revealing quantitative tool.
condition, especially localized strain
glossiness, can interfere concentrations.
with accurate
shearographic detection,
thus requiring the use of
surface dulling agents
(exception: thermal
shearography).
Strain Measurement Can be used to measure Relatively inexpensive, Individual strain gauges The output of a Depending on desired
static and dynamic and less bulky and better cannot be calibrated and resistance measuring sensitivity, resistance to
tensile and compressive resolution than are susceptible to circuit is expressed in drift, insensitivity to
strain, as well as extensometers (can unwanted noise and millivolts output per volt temperature variations,
shearing, Poisson, achieve an overall other sources of error input. or stability of installation,
bending, and torsional accuracy of better than ± such as expansion or a variety of strain
strains. 0.10% strain). contraction of the strain- gauges are available (for
gauge element, change example, semiconductor
in the resistivity, and wafer sensors, metallic
hysteresis and creep bonded strain gauges,
caused by imperfect thin-film and diffused
bonding. semiconductor strain
gauges).
Thermography Detects disbonds, Quick observation of Composites have The areal temperature Both contact (requires
delaminations, voids, large surfaces and temperature limits distribution is measured application of a coating)
pits, cracks, inclusions, identification of regions beyond which by mapping contours of and noncontact methods
and occlusions, that should be examined irreversible matrix and equal temperature (relies on detection of
especially in thin articles more carefully. fiber damage can occur. (isotherms), thus yielding infrared blackbody
under test having low Imperfection or a heat emission pattern radiation) are available.
thermal conductivity, low discontinuity detection related to surface and Thermography is either
reflectivity/high emissivity depends on orientation subsurface defects. passive or active; active
surfaces, and in of an imperfection or thermography can be
materials which dissipate discontinuity relative to further subdivided into
energy efficiently, the direction of heat pulse or lock-in
flow. In thicker materials, techniques.
only qualitative
indications of
imperfections or
discontinuities are
possible.
Ultrasonic Testing Detects sub-surface Detects sub-surface Requires a relatively flat Imperfections or Possible fluid
imperfections or imperfections or and smooth surface. discontinuities are entrapment; possible
discontinuities. There are discontinuities including Material type can affect directly recorded on fluid absorption into
two primary techniques; porosity, inclusions, and inspectability. amplitude images. porous materials such as
pulse echo for one sided delaminations. composites. Numerous
inspections and through techniques available
transmission for two including longitudinal,
sided inspections. shear or surface waves.
Attenuation can be
comparatively high in
PMCs compared to
metallic articles.
Visual Testing Detects disruptions on Low cost. Detect surface Requires direct line of Imperfections or Can find imperfections or
surfaces being viewed. imperfections or sight. discontinuities are discontinuities on
discontinuities including directly recorded on inaccessible surfaces if a
delaminations, fiber inspection borescope can be
breakage, impact documentation inserted and satisfactory
damage. sometimes photographs. imagining performed.
manufacturer’s name; part number; lot; date of lay-up or of patibility of data, data availability, criticality (length of data
cure, or both; date and pressure load of previous tests (for retention), specification change, specification revision and
pressure vessels); and previous service history (for in-service date, software and hardware considerations will also govern
and failed composite articles). Forwards and backwards com- how reporting is performed.
E2533 − 21
TABLE 3 Application Examples of Established NDT Procedures During Life Cycle
NDT Method Application
Acoustic Emission May be used for quality control of production and fabrication processes (for example, to evaluate adhesive bonding
after lay-up winding or curing), for proof-testing of pressure vessels after fabrication, and for periodic in-service and
health monitoring inspections prior to failure.
Computed Tomography May be used as a post-fabrication metrological method to verify engineering tolerances.
Leak Testing May be used to validate leak tightness following fabrication, and in-service re-qualification of pressure vessels. For
example, helium leak detection can be used during composite article fabrication to detect and seal leaks
permanently (preferable) or temporarily in such a manner to allow repair at a later time. Similarly, halogen gas leak
detection has been used in production examination.
Radiography and Radioscopy May be used during fabrication inspection to evaluate honeycomb core imperfections or discontinuities such as
node bonds, core-to-core splices, core-to-structure splices, porosity, included material as well as verification of
structural placement.
Shearography May be used in quality assurance, material optimization, and manufacturing process control.
Strain Measurement May be used during proof testing before placement into service, or during periodic re-qualification. Can be
destructive depending on the strain thresholds reached during test.
Thermography May be used to follow imperfection or discontinuity growth during service. If video thermographic equipment is
used, systems that are being dynamically tested or used can be examined in real-time.
Ultrasonic Testing Automatic recording systems allow parts to be removed from a processing line when defect severity exceeds
established limits. Measurement of the apparent attenuation in composite materials is useful in applications such
as comparison of crystallinity and fiber loading in different lots, or the assessment of environmental degradation.
The most common method is applied for laminar oriented defect detection such as impact damage causing
delamination fiber fracturing, included material, and porosity.
Visual Testing Used primarily for quality inspections of composite materials and components upon receipt (after fabrication and
before installation).
TABLE 4 Application of Established NDT Procedures During the Life Cycle of Polymeric Matrix Composites
Product and Process On-Line Process After Manufacture In-Service Health
Defect
Design and Optimization Control Inspection Inspection Monitoring
Acoustic Emission X X X X X
Computed Tomography X X
A
Leak Testing X X X
Radiography and Radioscopy X X X X
Shearography X X X X
Strain Measurement XX
Thermography XX
Ultrasonic Testing X X X X X
Visual Testing X X X X X
A
Applicable to composites used in storage and distribution of fluids and gases, for example, filament-wound pressure vessels.
6. Procedure eliminate unwanted frequencies. The conditionedAE signal is
then digitized and segmented into discrete AE waveform
6.1 When NDT produces an indication of a material
packetsthroughaprocessofthresholddetection.Digitalsignal
discontinuity,theindicationissubjecttointerpretationasfalse,
processing converts the transient waveform packets into ex-
nonrelevant, or relevant (Fig. 1). If the indication has been
tracted time and frequency features which describe the tran-
interpreted as relevant, the necessary subsequent evaluation
sientwaveform’sshape,size,andfrequencycontent.Insophis-
will result in the decision to accept or reject the composite
ticated approaches, these features are sometimes analyzed
material or component.
together using artificial intelligence, pattern recognition, or
7. Acoustic Emission
neural network techniques, or a combination thereof, to distin-
guishtrueAEsourcesfromnoise.Whenmultiplesensorsinan
7.1 General Procedure
array detect the sameAE transient, location determination can
7.1.1 Specially designed sensors (transducers) are used to
be accomplished using arrival time analysis (triangulation)
detect transient elastic stress waves (AE) in a material pro-
techniques. When multiple events are located close together
duced as a result of applied stress (t
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: E2533 − 17 E2533 − 21
Standard Guide for
Nondestructive TestingExamination of Polymer Matrix
Composites Used in Aerospace Applications
This standard is issued under the fixed designation E2533; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—An editorial correction was made to subsection 4.2 in November 2017.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This guide provides information to help engineers select appropriate nondestructive testing (NDT) methods to characterize
aerospace polymer matrix composites (PMCs). This guide does not intend to describe every inspection technology. Rather,
emphasis is placed on established NDT methods that have been developed into consensus standards and that are currently used
by industry. Specific practices and test methods are not described in detail, but are referenced. The referenced NDT practices and
test methods have demonstrated utility in quality assurance of PMCs during process design and optimization, process control, after
manufacture inspection, in-service inspection, and health monitoring.
1.2 This guide does not specify accept-reject criteria and is not intended to be used as a means for approving composite materials
or components for service.
1.3 This guide covers the following established NDT methods as applied to PMCs: Acoustic Emission (AE, Section 7),);
Computed Tomography (CT, Section 8),); Leak Testing (LT, Section 9),); Radiographic Testing, Computed Radiography, Digital
Radiography, and Radioscopy (RT, CR, DR, RTR, Section 10),); Shearography ((Section 11),); Strain Measurement (contact
methods, (Contact Methods, Section 12),); Thermography ((Section 13),); Ultrasonic Testing (UT, Section 14),); and Visual Testing
(VT, Section 15).
1.4 The value of this guide consists of the narrative descriptions of general procedures and significance and use sections for
established NDT practices and test methods as applied to PMCs. Additional information is provided about the use of currently
active standard documents (an emphasis is placed on applicable standard guides, practices, and test methods of ASTM Committee
E07 on Nondestructive Testing), geometry and size considerations, safety and hazards considerations, and information about
physical reference standards.
1.5 To ensure proper use of the referenced standard documents, there are recognized NDT specialists that are certified in
accordance with industry and company NDT specifications. It is recommended that a NDT specialist be a part of any composite
component design, quality assurance, in-service maintenance, or damage examination.
1.6 This guide summarizes the application of NDT procedures to fiber- and fabric-reinforced polymeric matrix composites. The
This guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.10 on Specialized NDT
Methods.
Current edition approved June 1, 2017Feb. 1, 2021. Published June 2017March 2021. Originally approved in 2009. Last previous edition approved in 20162017 as
ε1
E2533E2533 – 17 –16a. DOI: 10.1520/E2533-17E01.10.1520/E2533-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2533 − 21
composites of interest are primarily, but not exclusively, limited to those containing high modulus (greater than 20 GPa (3×10 psi))
fibers. Furthermore, an emphasis is placed on composites with continuous (versus discontinuous) fiber reinforcement.
1.7 This guide is applicable to PMCs containing, but not limited to, bismaleimide, epoxy, phenolic, poly(amide imide),
polybenzimidazole, polyester (thermosetting and thermoplastic), poly(ether ether ketone), poly(ether imide), polyimide (thermo-
setting and thermoplastic), poly(phenylene sulfide), or polysulfone matrices; and alumina, aramid, boron, carbon, glass, quartz, or
silicon carbide fibers.
NOTE 1—Per the discretion of the cognizant engineering organization, composite materials not developed and qualified in accordance with the guidelines
in CMH-17, Volumes 1 and 3 should have an approved material usage agreement.
1.8 The composite materials considered herein include uniaxial laminae, cross-ply laminates, angle-ply laminates, and sandwich
constructions. The composite components made therefrom include filament-wound pressure vessels, flight control surfaces, and
various structural composites.
1.9 For current and potential NDT procedures for finding indications of discontinuities in the composite overwrap and thin-walled
metallic liners in filament-wound pressure vessels, also known as composite overwrapped pressure vessels (COPVs), refer to
GuideGuides E2981. and E2982, respectively.
1.10 For a summary of the application of destructive ASTM standard practices and test methods (and other supporting standards)
to continuous-fiber reinforced PMCs, refer to Guide D4762.
1.11 Units—The values stated in SI units are to be regarded as the standard. The values given in parentheses after SI units are
provided for information only.only and are not considered standard.
1.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.13 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D3878 Terminology for Composite Materials
D4762 Guide for Testing Polymer Matrix Composite Materials
E94/E94M Guide for Radiographic Examination Using Industrial Radiographic Film
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
E214 Practice for Immersed Ultrasonic Testing by the Reflection Method Using Pulsed Longitudinal Waves (Withdrawn 2007)
E251 Test Methods for Performance Characteristics of Metallic Bonded Resistance Strain Gages
E317 Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-Echo Testing Instruments and Systems without the
Use of Electronic Measurement Instruments
E427 Practice for Testing for Leaks Using the Halogen Leak Detector Alkali-Ion Diode (Withdrawn 2013)
E432 Guide for Selection of a Leak Testing Method
E493/E493M Practice for Leaks Using the Mass Spectrometer Leak Detector in the Inside-Out Testing Mode
E498/E498M Practice for Leaks Using the Mass Spectrometer Leak Detector or Residual Gas Analyzer in the Tracer Probe
Mode
E499/E499M Practice for Leaks Using the Mass Spectrometer Leak Detector in the Detector Probe Mode
E515 Practice for Leaks Using Bubble Emission Techniques
E543 Specification for Agencies Performing Nondestructive Testing
E569/E569M Practice for Acoustic Emission Monitoring of Structures During Controlled Stimulation
E650/E650M Guide for Mounting Piezoelectric Acoustic Emission Sensors
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
E2533 − 21
E664/E664M Practice for the Measurement of the Apparent Attenuation of Longitudinal Ultrasonic Waves by Immersion
Method
E747 Practice for Design, Manufacture and Material Grouping Classification of Wire Image Quality Indicators (IQI) Used for
Radiology
E750 Practice for Characterizing Acoustic Emission Instrumentation
E976 Guide for Determining the Reproducibility of Acoustic Emission Sensor Response
E1000 Guide for Radioscopy
E1001 Practice for Detection and Evaluation of Discontinuities by the Immersed Pulse-Echo Ultrasonic Method Using
Longitudinal Waves
E1002 Practice for Leaks Using Ultrasonics
E1003 Practice for Hydrostatic Leak Testing
E1025 Practice for Design, Manufacture, and Material Grouping Classification of Hole-Type Image Quality Indicators (IQI)
Used for Radiography
E1065/E1065M Practice for Evaluating Characteristics of Ultrasonic Search Units
E1066/E1066M Practice for Ammonia Colorimetric Leak Testing
E1067/E1067M Practice for Acoustic Emission Examination of Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels
E1118/E1118M Practice for Acoustic Emission Examination of Reinforced Thermosetting Resin Pipe (RTRP)
E1211/E1211M Practice for Leak Detection and Location Using Surface-Mounted Acoustic Emission Sensors
E1213 Practice for Minimum Resolvable Temperature Difference for Thermal Imaging Systems
E1237 Guide for Installing Bonded Resistance Strain Gages
E1255 Practice for Radioscopy
E1311 Practice for Minimum Detectable Temperature Difference for Thermal Imaging Systems
E1316 Terminology for Nondestructive Examinations
E1324 Guide for Measuring Some Electronic Characteristics of Ultrasonic Testing Instruments
E1411 Practice for Qualification of Radioscopic Systems
E1419/E1419M Practice for Examination of Seamless, Gas-Filled, Pressure Vessels Using Acoustic Emission
E1441 Guide for Computed Tomography (CT)
E1543 Practice for Noise Equivalent Temperature Difference of Thermal Imaging Systems
E1570 Practice for Fan Beam Computed Tomographic (CT) Examination
E1603/E1603M Practice for Leakage Measurement Using the Mass Spectrometer Leak Detector or Residual Gas Analyzer in
the Hood Mode
E1647 Practice for Determining Contrast Sensitivity in Radiology
E1672 Guide for Computed Tomography (CT) System Selection
E1695 Test Method for Measurement of Computed Tomography (CT) System Performance
E1742E1742/E1742M Practice for Radiographic Examination
E1815 Test Method for Classification of Film Systems for Industrial Radiography
E1817 Practice for Controlling Quality of Radiological Examination by Using Representative Quality Indicators (RQIs)
E1862 Practice for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers
E1897 Practice for Measuring and Compensating for Transmittance of an Attenuating Medium Using Infrared Imaging
Radiometers
E1901 Guide for Detection and Evaluation of Discontinuities by Contact Pulse-Echo Straight-Beam Ultrasonic Methods
E1932 Guide for Acoustic Emission Examination of Small Parts
E1933 Practice for Measuring and Compensating for Emissivity Using Infrared Imaging Radiometers
E1934 Guide for Examining Electrical and Mechanical Equipment with Infrared Thermography
E1935 Test Method for Calibrating and Measuring CT Density
E2002 Practice for Determining Total Image Unsharpness and Basic Spatial Resolution in Radiography and Radioscopy
E2007 Guide for Computed Radiography
E2024/E2024M Practice for Atmospheric Leaks Using a Thermal Conductivity Leak Detector
E2033 Practice for Radiographic Examination Using Computed Radiography (Photostimulable Luminescence Method)
E2076/E2076M Practice for Examination of Fiberglass Reinforced Plastic Fan Blades Using Acoustic Emission
E2104 Practice for Radiographic Examination of Advanced Aero and Turbine Materials and Components
E2191/E2191M Practice for Examination of Gas-Filled Filament-Wound Composite Pressure Vessels Using Acoustic Emission
E2208 Guide for Evaluating Non-Contacting Optical Strain Measurement Systems
E2445/E2445M Practice for Performance Evaluation and Long-Term Stability of Computed Radiography Systems
E2446 Practice for Manufacturing Characterization of Computed Radiography Systems
E2580 Practice for Ultrasonic Testing of Flat Panel Composites and Sandwich Core Materials Used in Aerospace Applications
E2581 Practice for Shearography of Polymer Matrix Composites and Sandwich Core Materials in Aerospace Applications
E2582 Practice for Infrared Flash Thermography of Composite Panels and Repair Patches Used in Aerospace Applications
E2533 − 21
E2597/E2597M Practice for Manufacturing Characterization of Digital Detector Arrays
E2661/E2661M Practice for Acoustic Emission Examination of Plate-like and Flat Panel Composite Structures Used in
Aerospace Applications
E2662 Practice for Radiographic Examination of Flat Panel Composites and Sandwich Core Materials Used in Aerospace
Applications
E2736 Guide for Digital Detector Array Radiography
E2737 Practice for Digital Detector Array Performance Evaluation and Long-Term Stability
E2981 Guide for Nondestructive Examination of Composite Overwraps in Filament Wound Pressure Vessels Used in Aerospace
Applications
E2982 Guide for Nondestructive Testing of Thin-Walled Metallic Liners in Filament-Wound Pressure Vessels Used in Aerospace
Applications
F1364 Practice for Use of a Calibration Device to Demonstrate the Inspection Capability of an Interferometric Laser Imaging
Nondestructive Tire Inspection System
2.2 ASNT Standard:Standards and Documents:
ASNT CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel
SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing
Leak Testing, Volume 1, Nondestructive Testing Handbook
Nondestructive Testing Handbook, Visual and Optical Testing, Vol. 8
2.3 ASTM Adjuncts:
Curing Press Straining Block (13 Drawings)
2.4 ISO Standard:
ISO 9712 Non-destructive Testing—Qualification and Certification of NDT Personnel
2.5 AIA Standard:
NAS 410 Certification & Qualification of Nondestructive Test Personnel
2.6 MIL Documents:
CMH-17 Composite Materials Handbook, Volume 1. Polymer Matrix Composites, Guidelines For Characterization Of
Structural Materials (formerly MIL-HDBK-17)
CMH-17 Composite Materials Handbook, Volume 3. Polymer Matrix Composites, Materials Usage, Design, and Analysis
(formerly MIL-HDBK-17)
MIL-HDBK-6870 Inspection Program Requirements, Nondestructive for Aircraft and Missile Materials and Parts
MIL-HDBK-732A Nondestructive Testing Methods of Composite Materials—Acoustic Emission
MIL-HDBK-728 ⁄5A Radiologic Testing
MIL-HDBK-733 Nondestructive Testing Methods of Com- posite Materials—Radiography
MIL-HDBK-731 Nondestructive Testing Methods of Composite Materials—Thermography
MIL-HDBK-787 Nondestructive Testing Methods of Composite Materials—Ultrasonics
MIL-L-25567D Leak Detection Compound, Oxygen Systems
2.7 NASA Documents:
NASA-STD-(I)-5019 Fracture Control Requirements for Spaceflight Hardware
MSFC-RQMT-3479 Fracture Control Requirements for Composite and Bonded Vehicle and Payload Structures
2.8 Federal Standards:
NBS Handbook 114 General Radiation Safety Installations Using Nonmedical X-ray and Sealed Gamma Sources up to 10
MeV
Title 10, Code of Federal Regulations (CFR), Part 20, Standards for Protection Against Radiation
Title 21, Code of Federal Regulations (CFR), 1020.40, Safety Requirements of Cabinet X-ray Systems
Title 29, Code of Federal Regulations (CFR), 1910.96, Ionizing Radiation (X-rays, RF, etc.)
2.9 FDA Standards:
21 CFR 1040.10 Laser Products
21 CFR 1040.11 Specific Purpose Laser Products
Available from American Society for Nondestructive Testing, P. O. Box 28518, 1711 Arlington Lane, Columbus, OH 43228-0518.
Available from ASTM International Headquarters. Order Adjunct No. ADJf1364.
Available from Compressed Gas Association, 14501 George Carter Way, Suite 103, Chantilly VA 20151.International Organization for Standardization (ISO), ISO Central
Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland, https://www.iso.org.
Available from Aerospace Industries Association (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209, http://www.aia-aerospace.org.
Available for Standardization Documents Order Desk, Bldg 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Available from National Aeronautics and Space Administration, Technical Standards Program, 300 E. Street SW, Suite 5R30, Washington, D. C. 20546,
https://standards.nasa.gov/documents/nasa.
Available from National Technical Information Service (NTIS), U. S. Department of Commerce, 5285 Port Royal Road, Springfield,Springfield, VA 22161.
Available from NCRP Publications, 7010 Woodmont Ave., Suite 1016, Bethesda, MD 20814.
Available from Society of Automotive Engineers, Inc., 400 Commonwealth Dr., Warrendale, PA 15096-0001.
E2533 − 21
2.10 ASME Standard:
ASME Boiler and Pressure Vessel Code, Section V, Nondestructive Examination, Article 11, Acoustic Emission Examination
of Fiber-Reinforced Plastic Vessels
2.11 CGA Standard:
Pamphlet C-6.4 Methods for External Visual Inspection of Natural Gas Vehicle (NGV) and Hydrogen Gas Vehicle (HGV) Fuel
Containers and Their Installations
2.12 NCRP Documents:
NCRP 49 Structural Shielding Design and Evaluation for Medical Use of X-Rays and Gamma Rays of Energies up to 10 MeV
NCRP 51 Radiation Protection Design Guidelines for 0.1–100 MeV Particle Accelerator Facilities
NCRP 91 Recommendation on Limits for Exposures to Ionizing Radiation
2.13 SAE Standard:
SAE-ARP 1611, Revision A Quality Inspection Procedures, Composites: Tracer Fluoroscopy and Radiography
2.14 European Standards:
EN 14784-1, Non-Destructive Testing—Industrial Computed Radiography with Storage Phosphor Imaging Plates—Part 1:
Classification of Systems
EN 14784-2, Non-Destructive Testing—Industrial Computed Radiography with Storage Phosphor Imaging Plates— Part 2:
General Principles for Testing of Metallic Materials Using X-Rays and Gamma Rays
EN 13068-1, Non-Destructive Testing—Radioscopic Testing—Part 1: Quantitative Measurement of Imaging Properties
EN 13068-2, Non-Destructive Testing—Radioscopic Testing—Part 2: Check of Long Term Stability of Imaging Devices
EN 13068-3, Non-Destructive Testing—Radioscopic Testing—Part 3: General Principles of Radioscopic Testing of Metallic
Materials by X- and Gamma Rays
2.15 LIA Document:
ANSI, Z136.1-2000, Safe Use of Lasers
2.16 BSI Document:
EN 60825-1 Safety of Laser Products—Part 1: Equipment Classification, Requirements and User’s Guide
3. Terminology
3.1 Abbreviations—The following abbreviations are adopted in this guide: Acoustic Emission (AE), Computed Radiography (CR),
Computed Tomography (CT), Digital Radiography (DR), Leak Testing (LT), Radiographic Testing (RT), Radioscopy (RTR), and
Ultrasonic Testing (UT).
3.2 Definitions—Definitions of terms related to NDT of aerospace composites which appear in Terminology E1316 and
Terminology D3878 shallshould apply to the terms used in thethis guide.
3.3 Definitions of Terms Specific to This Standard:
3.3.1 aerospace—aerospace, n—any component that will be installed on a system that flies.
3.3.2 cognizant engineering organization—organization, n—the company, government agency, or other authority responsible for
the design, or end use, of the system or component for which NDT is required. This, in addition to the design personnel, may
include personnel from engineering, materials and process engineering, stress analysis, NDT, or quality groups and other, as
appropriate.
3.3.2.1 Discussion—
This, in addition to the design personnel, may include personnel from engineering, materials and process engineering, stress
analysis, NDT, or quality groups and other, as appropriate.
Available from European Committee for Standardization (Electrotechnical), CENELEC Customer service ([e-mail]).
Published by the Center for Devices and Radiological Health (CDRH) of the Food and Drug Administration (FDA), available from Government Printing Office
Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
www.asme.org.
Available from Compressed Gas Association (CGA), 14501 George Carter Way, Suite 103, Chantilly, VA 20151, http://www.cganet.com.
Available from NCRP Publications, 7010 Woodmont Ave., Suite 1016, Bethesda, MD 20814.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096, http://www.sae.org.
Available from European Committee for Standardization (Electrotechnical), CENELEC Customer service ([e-mail]).
Available from the Laser Institute of America, 13501 Ingenuity Drive, Suite 128, Orlando, FL 32826.
Available from the British Standards Institute, Institution (BSI), 389 Chiswick High Road, London,Rd., London W4 4AL, United Kingdom.U.K., http://
www.bsigroup.com.
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3.3.3 composite material—material, n—see Terminology D3878.
3.3.4 composite component—component, n—a finished part containing composite material(s) that is in its end use application
configuration, and which has undergone processing, fabrication, and assembly to the extent specified by the drawing, purchase
order, or contract.
3.3.5 disbond—disbond, n—see Terminology D3878.
3.3.6 in-service—in-service, n—refers to composite components that have completed initial fabrication and are in use (or in
storage) for their intended function.
3.3.7 microcrack—microcrack, n—invisible cracks (< 50 to 100 μm size) that are precursors to visible cracks. In angle-ply
continuous fiber-reinforced composites, for example, microcracks form preferentially under tensile loading in the matrix in off-axis
plies. Since most microcracks do not penetrate the reinforcing fibers, microcracks in a cross-plied tape laminate or in a laminate
made from cloth prepreg are usually limited to the thickness of a single ply.
3.3.7.1 Discussion—
In angle-ply continuous fiber-reinforced composites, for example, microcracks form preferentially under tensile loading in the
matrix in off-axis plies. Since most microcracks do not penetrate the reinforcing fibers, microcracks in a cross-plied tape laminate
or in a laminate made from cloth prepreg are usually limited to the thickness of a single ply.
3.3.8 reference standards—standards, n—objects that provide a known, reproducible, and repeatable response to a specific
stimulus. Maystimulus; may be in the form of hardware or software.
3.3.9 sandwich construction—construction, n—see Terminology D3878.
4. Summary of Guide
4.1 This guide describes and provides references for the practice and utilization of the following established NDT procedures as
applied to polymeric matrix composites:
4.1.1 Acoustic Emission (Section 7).
4.1.2 Computed Tomography (X-ray Method) (Section 8).
4.1.3 Leak Testing (Section 9).
4.1.4 Radiography, Computed Radiography, Digital Radiography with Digital Detector Array Systems, and Radioscopy (Section
10).
4.1.5 Shearography (Section 11).
4.1.6 Strain Measurement (Strain Gauges) (Section 12).
4.1.7 Infrared Thermography (Non-Contact Methods Using Infrared Camera) (Section 13).
4.1.8 Ultrasonic Testing (Section 14).
4.1.9 Visual Testing (Section 15).
4.2 NDT Method Selection—Composite components such as laminates, moldings, and subassemblies may be inspected by simple
procedures consisting of dimensional and tolerance measurements, weight and density determinations, cure determinations by
hardness measurements, visual testing for defects, and tapping for void determinations. If the integrity of the subassembly warrants
a more complete inspection, this can be accomplished by using various NDT procedures discussed in this guide. Nondestructive
tests can usually be made rapidly. However, nondestructive testing will, in general, add to component cost and should be used only
when warranted on critical applications. Also, the extent of NDT on composite parts depends on whether the part is a primary
E2533 − 21
structure safety of flight part, or secondary structure non-safety of flight part. The type or class of part is usually defined on the
engineering drawing. Some of the flaws that can be detected by NDT are given in Table 1.
4.3 Other critical defect characteristics not mentioned in Table 1 that need to be considered when establishing NDE procedures
include defect size, defect shape, defect depth, defect orientation, fiber volume fraction, resin rich regions, resin poor regions, cure
state, fiber sizing, fiber-matrix bonding, crazing (cracking of amorphous matrix resins due to exposure to stress or the service
environment), residual and internal stress, degradation (chemical and physical attack), and impact damage.
4.4 General Facility and Personnel Qualification—Minimum general requirements for NDT facilities and personnel qualification
are given in PracticeSpecification E543. This practicespecification can be used as a basis to evaluate testing or inspection agencies,
or both, and is intended for use for the qualifying or accrediting, or both, of testing or inspection agencies, public or private.
4.5 Personnel Certification—NDT personnel should be certified in accordance with a nationally or internationally recognized
practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS 410, ISO 9712, or a similar document. The practice or
standard used and its applicable revisions should be specified in any contractual agreement between the using parties.
4.6 Personnel Qualification—NDT personnel should be qualified by accepted training programs, applicable on-the-job training,
or a competent mentor or component manufacturer. Personnel will be only qualified to inspect parts that come under direct training
experience or production.
4.7 General Equipment and Instrumentation Considerations—General equipment and instrumentation considerations are provided
in PracticeSpecification E543. NDT method specific considerations are discussed in the appropriate section of this guide (Sections
77 – 15 to 15).
4.8 Reference Standards—Physical reference standards simulating target imperfections or discontinuities are used to validate NDT
results. The use of physical reference standards also helps to ensure reproducibility and repeatability of measurements. Certified
physical reference standards calibrated by accepted government or industrial agencies may be used.
4.9 Extent of Examination—Specific applications may require local regions or the entire component to be examined. Examination
may be real time or delayed based upon the availability of data. Examination may be direct, or indirect, on site or remote as
specified in the contractual agreement or established requirements documents.
TABLE 1 Flaws Detected By NDT Procedures
Radiography
Acoustic Computed Leak with DDA; Strain Ultrasonic Visual
Defect Shearography Thermography
Emission Tomography Testing Radiography, Measurement Testing Testing
CR, Radioscopy
Contamination X X X X
Damaged Filaments X X X
Delamination X X X X X X
Density Variation X X X X
Deformation under Load X X
Disbond X X X X X
A
Fiber Debonding X X X X
Fiber Misalignment X X X
Fractures X X X X X X
Inclusions X X X X X
Leaks X X X
Loose or Moving Parts X
B B,C
Microcracks X X X X X
D,E
Moisture X X X
Porosity X X X X X
F
Thickness Variation X X X X X
Undercure X
Volumetric Effects X
Voids X X X X X X
A
Can detect after impact (voids).
B
Depends on opening/size of crack.
C
Depends on angle of beam relative to planar defect and opening.
D
Only in central projection (Radiography, CR).
E
Radioscopic mode (Radiography with DDA).
F
For Radiography, applicable to CR and digitized films only.
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4.10 Timing of Examination—Examinations shallshould be performed in accordance with the contractual agreement or established
requirements documents, and may be performed during the life cycle of the article under test.
4.11 Type of Examinations—Many different NDT system configurations are possible due to the wide range of system components
available. It is important for the purchaser of NDT to understand the capability and limitations of the applicable configuration.
Selection of the NDT procedure and system shallshould be at the discretion of the testing agency unless specified by the purchaser
in a contract or requirements document (that is, engineering drawing, specifications, etc.).
4.12 A tabular comparison of most of the established NDT procedures discussed in the guide is given in Appendix X1 of
PracticeSpecification E543; namely, acoustic emission, leak testing, radiography, strain measurement, thermography (infrared),
and ultrasound are covered. The comparison summarizes properties sensed or measured, typical discontinuities detected,
representative application, applicable ASTM standards, and advantages and limitations. A similar overview is provided in Table
2.
5. Significance and Use
5.1 This guide references requirements that are intended to control the quality of NDT data. The purpose of this guide, therefore,
is not to establish acceptance criteria and therefore approve composite materials or components for aerospace service.
5.2 Following the discretion of the cognizant engineering organization, NDT for fracture control of composite and bonded
materials should follow additional guidance described in MIL-HDBK-6870, NASA-STD-(I)-5019, or MSFC-RQMT-3479, or a
combination thereof, as appropriate (not covered in this guide).
5.3 Certain procedures referenced in thethis guide are written so they can be specified on the engineering drawing, specification,
purchase order, or contract, for example, Practice E1742E1742/E1742M (Radiography).
5.4 Acceptance Criteria—Determination about whether a composite material or component meets acceptance criteria and is
suitable for aerospace service mustshould be made by the cognizant engineering organization. When examinations are performed
in accordance with the referenced documents in this guide, the engineering drawing, specification, purchase order, or contract
shallshould indicate the acceptance criteria.
5.4.1 Accept/reject criteria shallshould consist of a listing of the expected kinds of imperfections and the rejection level for each.
5.4.2 The classification of the articles under test into zones for various accept/reject criteria shallshould be determined from
contractual documents.
5.4.3 Rejection of Composite Articles—If the type, size, or quantities of defects are found to be outside the allowable limits
specified by the drawing, purchase order, or contract, the composite article shallshould be separated from acceptable articles,
appropriately identified as discrepant, and submitted for material review by the cognizant engineering organization, and
dispositioned as (1) acceptable as is, (2) subject to further rework or repair to make the materials or component acceptable, or (3)
scrapped when required by contractual documents.
5.4.4 Acceptance criteria and interpretation of result shallshould be defined in requirements documents prior to performing the
examination. Advance agreement should be reached between the purchaser and supplier regarding the interpretation of the results
of the examinations. All discontinuities having signals that exceed the rejection level as defined by the process requirements
documents shallshould be rejected unless it is determined from the part drawing that the rejectable discontinuities will not remain
in the finished part.
5.5 Life Cycle Considerations—The referenced NDT practices and test methods have demonstrated utility in quality assurance of
PMCs during the life cycle of the product. The modern NDT paradigm that has evolved and matured over the last twenty–five years
has been fully demonstrated to provide benefits from the application of NDT during: (a) product and process design and
optimization, (b) on-line process control, (c) after manufacture inspection, (d) in-service inspection, and (e) health monitoring.
5.5.1 In-process NDT can be used for feedback process control since all tests are based upon measurements which do not damage
the article under test.
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TABLE 2 General Overview of Established NDT Procedures
What Is Seen
NDT Method Applications Advantages Limitations Other Considerations
and Reported?
Acoustic Emission Global monitoring of Remote and continuous The part being inspected The AE technique Inspection tests and
composite structures to monitoring on an entire must be stressed by records transient elastic results are unique to
detect and locate active composite article in real mechanical, load, waves produced by each application and
sources in real time. time is possible. Can pressure, temperature, applied stress or should be conducted
also detect growth of or other stimulus. With resulting stress with expert oversight.
active imperfections or the exception of certain relaxation of the
discontinuities, and imperfections or composite material or
detect and determine the discontinuities that AE component. The
location of discontinuities detects by friction- mechanical waves are
and defects that may be generated AE (for produced as either burst
inaccessible by other example, delamination or continuous AE. AE
NDT procedures. surfaces rubbing), AE- activity, intensity and
inactive (non- severity correlated with
propagating) applied stress yield
imperfections or information on the
discontinuities cannot be degradation within the
detected and structurally article under test.
insignificant
imperfections or
discontinuities may
produce AE. Therefore,
the significance of a
detected AE source
cannot be assessed
unambiguously.
Computed Tomography Detects sub-surface Produces clear cross- Requires access to all A digitized cross- Tooling and/or part-
volumetric imperfections sectional image slices of sides of the article under sectional CT-density map handling fixtures may be
or discontinuities. an object. Obtains 3D test. Not very applicable (tomogram) of the article required.
Provides quantitative, imperfection or to the inspection of large under test. Allows full,
volumetric analysis of discontinuity data. areas, or objects with three dimensional CT-
imperfections or Extensive image high (>15) aspect ratios. density maps to be
discontinuities detectable processing capability. obtained for sufficiently
by other NDT small composite parts.
procedures. Also suitable
for measuring geometric
characteristics.
Computed Tomography Detects sub-surface Produces clear cross- Requires access to all A digitized cross- Tooling or part-handling
volumetric imperfections sectional image slices of sides of the article under sectional CT-density map fixtures, or both, may be
or discontinuities. an object. Obtains 3D test. Not very applicable (tomogram) of the article required.
Provides quantitative, imperfection or to the inspection of large under test. Allows full,
volumetric analysis of discontinuity data. areas, or objects with three dimensional CT-
imperfections or Extensive image high (>15) aspect ratios. density maps to be
discontinuities detectable processing capability. obtained for sufficiently
by other NDT small composite parts.
procedures. Also suitable
for measuring geometric
characteristics.
Leak Testing Any composite material Less ambiguous than Test equipment costs Qualitative indications, Different techniques are
or component across liquid penetrant testing; increase as the required for example bubbles, or available for
which a differential more sensitive than AE leak test sensitivity quantitative characterization of large
pressure exists and or UT. increases. measurements, for leaks (with rates as high
-2 3 -1 -1
where through-leakage example, detector as 10 Pa m s (10
3 -1
or in-leakage of product, deflections, that std cm s )) and small
air, water vapor, or other ascertain the presence leaks (rates less than
-5 3 -1 -4
contaminant over the or location, or 10 Pa m s (10 std
3 -1
projected service life are concentration or leak cm s )).
of concern. rate of a leaking fluid.
5.5.2 The applicability of NDT procedures to evaluate PMC materials and components during their life cycle is summarized in
Tables 3 and 4.
5.6 General Geometry and Size Considerations—Part contour, curvature, and surface condition may limit the ability of certain
tests to detect imperfections with the desired accuracy.
5.7 Reporting—Reports and records shallshould be specified by agreement between purchaser and supplier. It is recommended that
any NDT report or archival record contain information, when available, about the material type,type; method of fabrication,
E2533 − 21
TABLE 2 Continued
What Is Seen
NDT Method Applications Advantages Limitations Other Considerations
and Reported?
Radiography, Primarily detects sub- Film and some imaging Requires access to both Projected area and Part may need to be
Computed Radiography, surface imperfections or plates can be cut and sides of the article under density variation of moved to an X-ray lab;
Radiography with Digital discontinuities such as placed almost anywhere test. Accessibility may subsurface imperfections Film RT requires film
Detector Arrays, porosity & inclusions. on the part. Digital need to be evaluated. or discontinuities. storage and disposal of
Radioscopy Planar imperfections or images can be Unable to determine chemicals which can be
discontinuities are processed for additional depth of imperfections or expensive. Digital
detected if the beam is information and discontinuities; techniques (CR, DDA)
directed along the automated defect sometimes possible from are usually faster.
imperfection or recognition. In digital images after Radiation safety. In
discontinuity and the radioscopy, techniques calibration or with radioscopy, radiation
unsharpness is less than using an image additional X-ray safety more problematic
the imperfection or intensifier and DDA can exposures from different if a moving source is
discontinuity opening/ be automated by directions. used, versus movement
size. interfacing with a robot of part.
or part manipulator thus
allowing the potential for
a faster inspection.
Shearography Detects subsurface Well suited for high Subsurface imperfection An interference pattern Additional equipment is
imperfections or speed, automated or discontinuity must be created by subtracting or required to determine
discontinuities or inspection in production sufficiently large to superimposing images of surface derivative slope
changes in modulus or environments. cause measurable the article under test changes, and thus uses
out-of-plane deformation. surface deformation taken before and after the method as a
under load. Surface loading, thus revealing quantitative tool.
condition, especially localized strain
glossiness, can interfere concentrations.
with accurate
shearographic detection,
thus requiring the use of
surface dulling agents
(exception: thermal
shearography).
Shearography Detects subsurface Well suited for high Subsurface imperfection An interference pattern Additional equipment is
imperfections or speed, automated or discontinuity should created by subtracting or required to determine
discontinuities or inspection in production be sufficiently large to superimposing images of surface derivative slope
changes in modulus or environments. cause measurable the article under test changes, and thus uses
out-of-plane deformation. surface deformation taken before and after the method as a
under load. Surface loading, thus revealing quantitative tool.
condition, especially localized strain
glossiness, can interfere concentrations.
with accurate
shearographic detection,
thus requiring the use of
surface dulling agents
(exception: thermal
shearography).
Strain Measurement Can be used to measure Relatively inexpensive, Individual strain gauges The output of a Depending on desired
static and dynamic and less bulky and better cannot be calibrated and resistance measuring sensitivity, resistance to
tensile and compressive resolution than are susceptible to circuit is expressed in drift, insensitivity to
strain, as well as extensometers (can unwanted noise and millivolts output per volt temperature variations,
shearing, Poisson, achieve an overall other sources of error input. or stability of installation,
bending, and torsional accuracy of better than ± such as expansion or a variety of strain
strains. 0.10% strain). contraction of the strain- gauges are available (for
gauge element, change example, semiconductor
in the resistivity, and wafer sensors, metallic
hysteresis and creep bonded strain gauges,
caused by imperfect thin-film and diffused
bonding. semiconductor strain
gauges).
manufacturers name, part number, lot,fabrication; manufacturer’s name; part number; lot; date of lay-up and/oror of cure, or both;
date and pressure load of previous tests (for pressure vessels),vessels); and previous service history (for in-service and failed
composite articles). Forwards and backwards compatibility of data, data availability, criticality (length of data retention),
specification change, specification revision and date, software and hardware considerations will also govern how reporting is
performed.
6. Procedure
6.1 When NDT produces an indication of a material discontinuity, the indication is subject to interpretation as false, nonrelevant,
E2533 − 21
TABLE 2 Continued
What Is Seen
NDT Method Applications Advantages Limitations Other Considerations
and Reported?
Thermography Detects disbonds, Quick observation of Composites have The areal temperature Both contact (requires
delaminations, voids, large surfaces and temperature limits distribution is measured application of a coating)
pits, cracks, inclusions, identification of regions beyond which by mapping contours of and noncontact methods
and occlusions, that should be examined irreversible matrix and equal temperature (relies on detection of
especially in thin articles more carefully. fiber damage can occur. (isotherms), thus yielding infrared blackbody
under test having low Imperfection or a heat emission pattern radiation) are available.
thermal conductivity, low discontinuity detection related to surface and Thermography is either
reflectivity/high emissivity depends on orientation subsurface defects. passive or active, active
surfaces, and in of an imperfection or thermography can be
materials which dissipate discontinuity relative to further subdivided into
energy efficiently, the direction of heat pulse or lock-in
flow. In thicker materials, techniques.
only qualitative
indications of
imperfections or
discontinuities are
possible.
Thermography Detects disbonds, Quick observation of Composites have The areal temperature Both contact (requires
delaminations, voids, large surfaces and temperature limits distribution is measured application of a coating)
pits, cracks, inclusions, identification of regions beyond which by mapping contours of and noncontact methods
and occlusions, that should be examined irreversible matrix and equal temperature (relies on detection of
especially in thin articles more carefully. fiber damage can occur. (isotherms), thus yielding infrared blackbody
under test having low Imperfection or a heat emission pattern radiation) are available.
thermal conductivity, low discontinuity detection related to surface and Thermography is either
reflectivity/high emissivity depends on orientation subsurface defects. passive or active; active
surfaces, and in of an imperfection or thermography can be
materials which dissipate discontinuity relative to further subdivided into
energy efficiently, the direction of heat pulse or lock-in
flow. In thicker materials, techniques.
only qualitative
indications of
imperfections or
discontinuities are
possible.
Ultrasonic Testing Detects sub-surface Detects sub-surface Requires a relatively flat Imperfections or Possible fluid
imperfections or imperfections or and smooth surface. discontinuities are entrapment; possible
discontinuities. There are discontinuities including Material type can affect directly recorded on
...