ASTM E2581-14(2019)
(Practice)Standard Practice for Shearography of Polymer Matrix Composites and Sandwich Core Materials in Aerospace Applications
Standard Practice for Shearography of Polymer Matrix Composites and Sandwich Core Materials in Aerospace Applications
SIGNIFICANCE AND USE
5.1 Shearography is commonly used during product process design and optimization, process control, after manufacture inspection, and in service inspection, and can be used to measure static and dynamic axial (tensile and compressive) strain, as well as shearing, Poisson, bending, and torsional strains. The general types of defects detected by shearography include delamination, deformation under load, disbond/unbond, microcracks, and thickness variation.
5.2 Additional information is given in Guide E2533 about the advantages and limitations of the shearography technique, use of related ASTM documents, specimen geometry and size considerations, calibration and standardization, and physical reference standards.
5.3 For procedures for shearography of filament-wound pressure vessels, otherwise known as composite overwrapped pressure vessels, consult Guide E2982.
5.4 Factors that influence shearography and therefore shall be reported include but are not limited to the following: laminate (matrix and fiber) material, lay-up geometry, fiber volume fraction (flat panels); facing material, core material, facing stack sequence, core geometry (cell size); core density, facing void content, and facing volume percent reinforcement (sandwich core materials); processing and fabrication methods, overall thickness, specimen alignment, specimen conditioning, specimen geometry, and test environment (flat panels and sandwich core materials). Shearography has been used with excellent results for composite and metal face sheet sandwich panels with both honeycomb and foam cores, solid monolithic composite laminates, foam cryogenic fuel tank insulation, bonded cork insulation, aircraft tires, elastomeric and plastic coatings. Frequently, defects at multiple and far side bond lines can be detected.
SCOPE
1.1 This practice describes procedures for shearography of polymer matrix composites and sandwich core materials made entirely or in part from fiber-reinforced polymer matrix composites. The composite materials under consideration typically contain continuous high modulus (greater than 20 GPa (3×106 psi)) fibers, but may also contain discontinuous fiber, fabric, or particulate reinforcement.
1.2 This practice describes established shearography procedures that are currently used by industry and federal agencies that have demonstrated utility in quality assurance of polymer matrix composites and sandwich core materials during product process design and optimization, manufacturing process control, after manufacture inspection, and in service inspection.
1.3 This practice has utility for testing of polymer matrix composites and sandwich core materials containing but not limited to bismaleimide, epoxy, phenolic, poly(amideimide), polybenzimidazole, polyester (thermosetting and thermoplastic), poly(ether ether ketone), poly(ether imide), polyimide (thermosetting and thermoplastic), poly(phenylene sulfide), or polysulfone matrices; and alumina, aramid, boron, carbon, glass, quartz, or silicon carbide fibers. Typical as-fabricated geometries include uniaxial, cross-ply and angle-ply laminates; as well as honeycomb and foam core sandwich materials and structures.
1.4 This practice does not specify accept-reject criteria and is not intended to be used as a means for approving polymer matrix composites or sandwich core materials for service.
1.5 To ensure proper use of the referenced standards, there are recognized nondestructive testing (NDT) specialists that are certified according to industry and company NDT specifications. It is recommended that an NDT specialist be a part of any composite component design, quality assurance, in-service maintenance, or damage examination activity.
1.6 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, health, and environmental pra...
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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: E2581 −14 (Reapproved 2019)
Standard Practice for
Shearography of Polymer Matrix Composites and Sandwich
Core Materials in Aerospace Applications
This standard is issued under the fixed designation E2581; 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 anycompositecomponentdesign,qualityassurance,in-service
maintenance, or damage examination activity.
1.1 This practice describes procedures for shearography of
1.6 This standard does not purport to address all of the
polymer matrix composites and sandwich core materials made
safety concerns, if any, associated with its use. It is the
entirely or in part from fiber-reinforced polymer matrix com-
responsibility of the user of this standard to establish appro-
posites. The composite materials under consideration typically
priate safety, health, and environmental practices and deter-
contain continuous high modulus (greater than 20 GPa
mine the applicability of regulatory limitations prior to use.
(3×106psi)) fibers, but may also contain discontinuous fiber,
1.7 This international standard was developed in accor-
fabric, or particulate reinforcement.
dance with internationally recognized principles on standard-
1.2 This practice describes established shearography proce-
ization established in the Decision on Principles for the
dures that are currently used by industry and federal agencies
Development of International Standards, Guides and Recom-
that have demonstrated utility in quality assurance of polymer
mendations issued by the World Trade Organization Technical
matrix composites and sandwich core materials during product
Barriers to Trade (TBT) Committee.
process design and optimization, manufacturing process
control, after manufacture inspection, and in service inspec-
2. Referenced Documents
tion.
2.1 ASTM Standards:
1.3 This practice has utility for testing of polymer matrix
C274Terminology of Structural Sandwich Constructions
composites and sandwich core materials containing but not
(Withdrawn 2016)
limited to bismaleimide, epoxy, phenolic, poly(amideimide),
D3878Terminology for Composite Materials
polybenzimidazole, polyester (thermosetting and
D5687/D5687MGuide for Preparation of Flat Composite
thermoplastic), poly(ether ether ketone), poly(ether imide),
Panels with Processing Guidelines for Specimen Prepara-
polyimide (thermosetting and thermoplastic), poly(phenylene
tion
sulfide), or polysulfone matrices; and alumina, aramid, boron,
E543Specification forAgencies Performing Nondestructive
carbon, glass, quartz, or silicon carbide fibers. Typical as-
Testing
fabricatedgeometriesincludeuniaxial,cross-plyandangle-ply
E1309 Guide for Identification of Fiber-Reinforced
laminates; as well as honeycomb and foam core sandwich
Polymer-Matrix Composite Materials in Databases (With-
materials and structures.
drawn 2015)
1.4 This practice does not specify accept-reject criteria and
E1316Terminology for Nondestructive Examinations
is not intended to be used as a means for approving polymer
E1434Guide for Recording Mechanical Test Data of Fiber-
matrix composites or sandwich core materials for service.
ReinforcedCompositeMaterialsinDatabases(Withdrawn
2015)
1.5 To ensure proper use of the referenced standards, there
E1471Guide for Identification of Fibers, Fillers, and Core
are recognized nondestructive testing (NDT) specialists that
Materials in Computerized Material Property Databases
are certified according to industry and company NDT specifi-
(Withdrawn 2015)
cations. It is recommended that an NDT specialist be a part of
1 2
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
structive Testing and is the direct responsibility of Subcommittee E07.10 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Specialized NDT Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2019. Published January 2020. Originally the ASTM website.
approved in 2007. Last previous edition approved in 2014 as E2581–14. DOI: The last approved version of this historical standard is referenced on
10.1520/E2581-14R19. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2581 − 14 (2019)
E2533Guide for Nondestructive Testing of Polymer Matrix 3. Terminology
Composites Used in Aerospace Applications
3.1 Definitions—Definition of terms related to structural
E2982Guide for Nondestructive Testing of Thin-Walled
sandwich constructions, NDT, and composites appearing in
MetallicLinersinFilament-WoundPressureVesselsUsed
Terminologies C274, E1316, and D3878, respectively, shall
in Aerospace Applications
apply to the terms used in this standard.
F1364Practice for Use of a Calibration Device to Demon-
3.2 Definitions of Terms Specific to This Standard:
strate the Inspection Capability of an Interferometric
3.2.1 aerospace—any component that will be installed on a
Laser Imaging Nondestructive Tire Inspection System
4 system that flies.
2.2 ASNT Standards:
3.2.2 beam splitter—an optical element capable of splitting
SNT-TC-1ARecommended Practice for Personnel Qualifi-
a single beam of coherent laser light into two beams. Beam
cation and Certification in Nondestructive Testing
splitters are key elements of Michelson Type Image Shearing
ANSI/ASNTCP-189Standard for Qualification and Certifi-
Interferometers.
cation of Nondestructive Testing Personnel
2.3 AIA Document:
3.2.3 cognizant engineering organization—the company,
NAS-410Certification and Qualification of Nondestructive
agency, or other authority responsible for the design or after
Test Personnel
delivery, end use of the system or component for which laser
2.4 BSI Document: holographic or laser shearographic examination is required; in
EN 60825-1Safety of Laser Products - Part 1: Equipment addition to design personnel, this may include personnel from
Classification, Requirements, and User’s Guide material and process engineering, stress anaylsis, NDT, or
quality groups and others as appropriate.
2.5 LIA Document:
ANSI Z136.1-2000Safe Use of Lasers
3.2.4 coherent light source—a light source that converts
2.6 Federal Standards:
electrical energy to a monochromatic beam of light having
21 CFR 1040.10Laser products
uniform phase over a minimum specified length known as the
21 CFR 1040.11Specific purpose laser products
coherent length.
29 CFR 1910.95Occupational Noise Exposure
3.2.5 component—the part(s) or element(s) of a system
described, assembled, or processed to the extent specified by
the drawing.
AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
3.2.6 composite material—see Terminology D3878.
28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Available fromAerospace IndustriesAssociation ofAmerica, Inc. (AIA), 1000
3.2.7 composite component—a finished part containing
WilsonBlvd.,Suite1700,Arlington,VA22209-3928,http://www.aia-aerospace.org.
compositematerial(s)thatisinitsenduseapplicationconfigu-
Available from British Standards Institution (BSI), 389 Chiswick High Rd., ration and which has undergone processing, fabrication, and
London W4 4AL, U.K., http://www.bsigroup.com.
assembly to the extent specified by the drawing, purchase
AvailablefromtheLaserInstituteofAmerica,13501IntegrityDrive,Suite128,
order, or contract.
Orlando FL 32826.
AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
3.2.8 core crush—a collapse, distortion, or compression of
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
core material in a sandwich structure.
www.access.gpo.gov.
FIG. 1 Schematic diagram of a Michelson type shearing interferometer shown with a shearography calibration device consisting of a
metal plate with a machined flat bottomed hole creating a deformable plate with a precision mechanical mechanism for loading at the
center point.
E2581 − 14 (2019)
3.2.9 core separation—a partial or complete breaking of 3.2.23 scan plan—a designed sequence of steps for posi-
honeycomb core node bonds. tioning and adjusting a shearography camera to accomplish a
desired inspection. Scan plans shall include camera field of
3.2.10 disbond, unbond —see Terminology D3878.
view,percentageofimageoverlap,positionsequencesforeach
3.2.11 de-correlation—loss of shearography phase data
area to be tested, test number, and location in a coordinate
causedbytestpartdeformationexceedingtheresolutionofthe
system appropriate for test object geometry and access.
shearing interferometer or motion occurs between the test
3.2.24 shearogram—the resulting image from the complex
object and shearing interferometer during data acquisition.
arithmetic combination of interferograms made with an image
3.2.12 delamination—see Terminology D3878.
shearing interferometer and presented for interpretation in
3.2.13 displacement derivatives (∂w/∂x)— rate of spatial
various image processing algorithms including wrapped phase
displacement change, where w is the surface displacement and
maps (static or real-time), unwrapped phase maps, integrated,
x is the surface coordinates.
Doppler shift map.
3.2.14 fringe pattern—a set of lines in a subtraction or
3.2.25 shearography camera, shear camera—an image
wrapped phase shearogram that represents the locus of equal
shearing interferometer used for shearography nondestructive
out-of-plane deformation derivative.
testing, usually including features for adjustment of focus, iris,
3.2.15 impact damage—fracturing of epoxy matrix, fiber
zoom, shear vector, and projection and adjustment of coherent
breakage, inter-laminar delamination of monolithic
light onto the test object area to be inspected.
composites, composite sandwich structure face sheets due to
3.2.26 shear vector—the separation vector between two
impact, characterized by visible dimple surface compression,
identicalimagesofthetargetintheoutputofanimageshearing
or fiber breakage caused by impact strike and non-visible
interferometer. The Shear vector is expressed in degrees of
subsurface matrix cracking and delamination.
anglefromthe Xaxis,withamaximumof90°,with+beingin
3.2.16 inclusion—foreign objects or material including but
the positive Y direction and – in the negative Y direction. The
not limited to particles, chips, backing films, razor blades, or
shear distance between identical points in the two sheared
tools of varying sizes which are inadvertently left in a
images expressed in inches or mm. (See Fig. 2 shear vector
composite lay-up.
angle convention).
3.2.17 indication—the observation or evidence of a condi-
3.2.27 stressing device—the means to apply a measurable
tionresultingfromtheshearographicexaminationthatrequires
and repeatable engineered stress to the test object during
interpretation to determine its significance, characterized by
shearographyinspection.Theappliedstressmaybeintheform
dimensions, area, s/n ratio, or other quantitative measurement.
of a partial vacuum, pressure, heat, vibration, magnetic field,
3.2.18 laser shearography inspection, shearography
electric field, microwave, or mechanical load.Also referred to
inspection, shearography—inspection method utilizing inter-
as excitation or excitation method.
ferometric imaging of deformation derivatives compared be-
3.2.28 void—anempty,unoccupiedspaceinlaminate.Voids
tween different strain states and designed to reveal non-
are associated with bridging and resin starved areas.
homogeneities, material changes and structural defects
throughout the volume of the material.
4. Summary of Practice
3.2.19 out-of-plane displacement—the local deformation of
4.1 Shearographynondestructiveinspectionreferstotheuse
a test part, normal to the surface, caused by the application of
ofanimageshearinginterferometertoimagelocalout-of-plane
an engineered force acting on a non-homogeneity or defect in
deformation derivatives on the test part surface in response to
a composite material.
a change in the applied engineered load. Shearography images
3.2.20 polymer matrix composite—any fiber-reinforced
tend to show only the local deformation on the target surface
composite lay-up consisting of laminae (plies) with one or
due to the presence of a surface or subsurface flaw,
more orientations with respect to some reference direction that
delaminations,coredamage,orcoresplicejointseparations,as
are consolidated by press, vacuum bagging, or autoclave to
well as impact damage.
yield an engineered part article or structure.
4.2 Typical applied loads to the test part are dependant on
3.2.21 porosity—condition of trapped pockets of air, gas, or
thetestpartmaterialreactiontotheinducedload.Theoptimum
void within solid materials, usually expressed as a percentage
load type and magnitude depend on the flaw type and flaw
of the total nonsolid volume (solid + nonsolid) of a unit
depth and are best determined before serial testing by making
quantity of material.
trial measurements. Care is taken to ensure that the magnitude
3.2.22 sandwich core material—an engineered part, article,
oftheappliedloadisacceptablybelowthedamagethresholdof
or structure made up of two or more sheets of composite
a given test article. The applied load can be any of the
laminate, metal, or other material designed to support in-plane
following: heat, mechanical vibration, acoustic vibration, pres-
tensile or compressive loads, separated by and bonded to inner
sure and vacuum, electric fields, magnetic fields, microwave,
core(s) material(s) designed to support normal compressive
or mechanical load.
and tensile loads such as metal or composite honeycomb, open
andclosedcellfoam,waveformedmaterial,bondedcomposite 4.3 Shearography NDT systems use a common path
tubes, or naturally occurring material such as end grain balsa Michelson, birefringant, or beam splitter type shearing inter-
wood. ferometer for imaging defects. Some of the most current
E2581 − 14 (2019)
FIG. 2 Shear vector angle convention: Starting with the shear camera adjusted for a 0° shear condition, the sheared image is moved to
the right (+X) or up/down, never adjusted in the directio
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E2581 − 14 (Reapproved 2019)
Standard Practice for
Shearography of Polymer Matrix Composites and Sandwich
Core Materials in Aerospace Applications
This standard is issued under the fixed designation E2581; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope any composite component design, quality assurance, in-service
maintenance, or damage examination activity.
1.1 This practice describes procedures for shearography of
1.6 This standard does not purport to address all of the
polymer matrix composites and sandwich core materials made
safety concerns, if any, associated with its use. It is the
entirely or in part from fiber-reinforced polymer matrix com-
responsibility of the user of this standard to establish appro-
posites. The composite materials under consideration typically
priate safety, health, and environmental practices and deter-
contain continuous high modulus (greater than 20 GPa
mine the applicability of regulatory limitations prior to use.
(3×106 psi)) fibers, but may also contain discontinuous fiber,
1.7 This international standard was developed in accor-
fabric, or particulate reinforcement.
dance with internationally recognized principles on standard-
1.2 This practice describes established shearography proce-
ization established in the Decision on Principles for the
dures that are currently used by industry and federal agencies
Development of International Standards, Guides and Recom-
that have demonstrated utility in quality assurance of polymer
mendations issued by the World Trade Organization Technical
matrix composites and sandwich core materials during product
Barriers to Trade (TBT) Committee.
process design and optimization, manufacturing process
control, after manufacture inspection, and in service inspec-
2. Referenced Documents
tion.
2.1 ASTM Standards:
1.3 This practice has utility for testing of polymer matrix
C274 Terminology of Structural Sandwich Constructions
composites and sandwich core materials containing but not
(Withdrawn 2016)
limited to bismaleimide, epoxy, phenolic, poly(amideimide),
D3878 Terminology for Composite Materials
polybenzimidazole, polyester (thermosetting and
D5687/D5687M Guide for Preparation of Flat Composite
thermoplastic), poly(ether ether ketone), poly(ether imide),
Panels with Processing Guidelines for Specimen Prepara-
polyimide (thermosetting and thermoplastic), poly(phenylene
tion
sulfide), or polysulfone matrices; and alumina, aramid, boron,
E543 Specification for Agencies Performing Nondestructive
carbon, glass, quartz, or silicon carbide fibers. Typical as-
Testing
fabricated geometries include uniaxial, cross-ply and angle-ply
E1309 Guide for Identification of Fiber-Reinforced
laminates; as well as honeycomb and foam core sandwich
Polymer-Matrix Composite Materials in Databases (With-
materials and structures.
drawn 2015)
1.4 This practice does not specify accept-reject criteria and
E1316 Terminology for Nondestructive Examinations
is not intended to be used as a means for approving polymer
E1434 Guide for Recording Mechanical Test Data of Fiber-
matrix composites or sandwich core materials for service.
Reinforced Composite Materials in Databases (Withdrawn
2015)
1.5 To ensure proper use of the referenced standards, there
E1471 Guide for Identification of Fibers, Fillers, and Core
are recognized nondestructive testing (NDT) specialists that
Materials in Computerized Material Property Databases
are certified according to industry and company NDT specifi-
(Withdrawn 2015)
cations. It is recommended that an NDT specialist be a part of
1 2
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
structive Testing and is the direct responsibility of Subcommittee E07.10 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Specialized NDT Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2019. Published January 2020. Originally the ASTM website.
approved in 2007. Last previous edition approved in 2014 as E2581– 14. DOI: The last approved version of this historical standard is referenced on
10.1520/E2581-14R19. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2581 − 14 (2019)
E2533 Guide for Nondestructive Testing of Polymer Matrix 3. Terminology
Composites Used in Aerospace Applications
3.1 Definitions—Definition of terms related to structural
E2982 Guide for Nondestructive Testing of Thin-Walled
sandwich constructions, NDT, and composites appearing in
Metallic Liners in Filament-Wound Pressure Vessels Used
Terminologies C274, E1316, and D3878, respectively, shall
in Aerospace Applications
apply to the terms used in this standard.
F1364 Practice for Use of a Calibration Device to Demon-
3.2 Definitions of Terms Specific to This Standard:
strate the Inspection Capability of an Interferometric
3.2.1 aerospace—any component that will be installed on a
Laser Imaging Nondestructive Tire Inspection System
4 system that flies.
2.2 ASNT Standards:
3.2.2 beam splitter—an optical element capable of splitting
SNT-TC-1A Recommended Practice for Personnel Qualifi-
a single beam of coherent laser light into two beams. Beam
cation and Certification in Nondestructive Testing
splitters are key elements of Michelson Type Image Shearing
ANSI/ASNT CP-189 Standard for Qualification and Certifi-
Interferometers.
cation of Nondestructive Testing Personnel
2.3 AIA Document:
3.2.3 cognizant engineering organization—the company,
NAS-410 Certification and Qualification of Nondestructive
agency, or other authority responsible for the design or after
Test Personnel
delivery, end use of the system or component for which laser
2.4 BSI Document: holographic or laser shearographic examination is required; in
EN 60825-1 Safety of Laser Products - Part 1: Equipment addition to design personnel, this may include personnel from
Classification, Requirements, and User’s Guide material and process engineering, stress anaylsis, NDT, or
2.5 LIA Document: quality groups and others as appropriate.
ANSI Z136.1-2000 Safe Use of Lasers
3.2.4 coherent light source—a light source that converts
2.6 Federal Standards:
electrical energy to a monochromatic beam of light having
21 CFR 1040.10 Laser products
uniform phase over a minimum specified length known as the
21 CFR 1040.11 Specific purpose laser products
coherent length.
29 CFR 1910.95 Occupational Noise Exposure
3.2.5 component—the part(s) or element(s) of a system
described, assembled, or processed to the extent specified by
the drawing.
Available from American Society for Nondestructive Testing (ASNT), P.O. Box
3.2.6 composite material—see Terminology D3878.
28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Available from Aerospace Industries Association of America, Inc. (AIA), 1000
3.2.7 composite component—a finished part containing
Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http://www.aia-aerospace.org.
composite material(s) that is in its end use application configu-
ration and which has undergone processing, fabrication, and
Available from British Standards Institution (BSI), 389 Chiswick High Rd.,
London W4 4AL, U.K., http://www.bsigroup.com.
assembly to the extent specified by the drawing, purchase
Available from the Laser Institute of America, 13501 Integrity Drive, Suite 128,
order, or contract.
Orlando FL 32826.
Available from U.S. Government Printing Office Superintendent of Documents,
3.2.8 core crush—a collapse, distortion, or compression of
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
core material in a sandwich structure.
www.access.gpo.gov.
FIG. 1 Schematic diagram of a Michelson type shearing interferometer shown with a shearography calibration device consisting of a
metal plate with a machined flat bottomed hole creating a deformable plate with a precision mechanical mechanism for loading at the
center point.
E2581 − 14 (2019)
3.2.9 core separation—a partial or complete breaking of 3.2.23 scan plan—a designed sequence of steps for posi-
honeycomb core node bonds. tioning and adjusting a shearography camera to accomplish a
desired inspection. Scan plans shall include camera field of
3.2.10 disbond, unbond —see Terminology D3878.
view, percentage of image overlap, position sequences for each
3.2.11 de-correlation—loss of shearography phase data
area to be tested, test number, and location in a coordinate
caused by test part deformation exceeding the resolution of the
system appropriate for test object geometry and access.
shearing interferometer or motion occurs between the test
3.2.24 shearogram—the resulting image from the complex
object and shearing interferometer during data acquisition.
arithmetic combination of interferograms made with an image
3.2.12 delamination—see Terminology D3878.
shearing interferometer and presented for interpretation in
3.2.13 displacement derivatives (∂w/∂x)— rate of spatial
various image processing algorithms including wrapped phase
displacement change, where w is the surface displacement and
maps (static or real-time), unwrapped phase maps, integrated,
x is the surface coordinates.
Doppler shift map.
3.2.14 fringe pattern—a set of lines in a subtraction or
3.2.25 shearography camera, shear camera—an image
wrapped phase shearogram that represents the locus of equal
shearing interferometer used for shearography nondestructive
out-of-plane deformation derivative.
testing, usually including features for adjustment of focus, iris,
3.2.15 impact damage—fracturing of epoxy matrix, fiber
zoom, shear vector, and projection and adjustment of coherent
breakage, inter-laminar delamination of monolithic
light onto the test object area to be inspected.
composites, composite sandwich structure face sheets due to
3.2.26 shear vector—the separation vector between two
impact, characterized by visible dimple surface compression,
identical images of the target in the output of an image shearing
or fiber breakage caused by impact strike and non-visible
interferometer. The Shear vector is expressed in degrees of
subsurface matrix cracking and delamination.
angle from the X axis, with a maximum of 90°, with + being in
3.2.16 inclusion—foreign objects or material including but
the positive Y direction and – in the negative Y direction. The
not limited to particles, chips, backing films, razor blades, or
shear distance between identical points in the two sheared
tools of varying sizes which are inadvertently left in a
images expressed in inches or mm. (See Fig. 2 shear vector
composite lay-up.
angle convention).
3.2.17 indication—the observation or evidence of a condi-
3.2.27 stressing device—the means to apply a measurable
tion resulting from the shearographic examination that requires
and repeatable engineered stress to the test object during
interpretation to determine its significance, characterized by
shearography inspection. The applied stress may be in the form
dimensions, area, s/n ratio, or other quantitative measurement.
of a partial vacuum, pressure, heat, vibration, magnetic field,
3.2.18 laser shearography inspection, shearography
electric field, microwave, or mechanical load. Also referred to
inspection, shearography—inspection method utilizing inter-
as excitation or excitation method.
ferometric imaging of deformation derivatives compared be-
3.2.28 void—an empty, unoccupied space in laminate. Voids
tween different strain states and designed to reveal non-
are associated with bridging and resin starved areas.
homogeneities, material changes and structural defects
throughout the volume of the material.
4. Summary of Practice
3.2.19 out-of-plane displacement—the local deformation of
4.1 Shearography nondestructive inspection refers to the use
a test part, normal to the surface, caused by the application of
of an image shearing interferometer to image local out-of-plane
an engineered force acting on a non-homogeneity or defect in
deformation derivatives on the test part surface in response to
a composite material.
a change in the applied engineered load. Shearography images
3.2.20 polymer matrix composite—any fiber-reinforced
tend to show only the local deformation on the target surface
composite lay-up consisting of laminae (plies) with one or
due to the presence of a surface or subsurface flaw,
more orientations with respect to some reference direction that
delaminations, core damage, or core splice joint separations, as
are consolidated by press, vacuum bagging, or autoclave to
well as impact damage.
yield an engineered part article or structure.
4.2 Typical applied loads to the test part are dependant on
3.2.21 porosity—condition of trapped pockets of air, gas, or
the test part material reaction to the induced load. The optimum
void within solid materials, usually expressed as a percentage
load type and magnitude depend on the flaw type and flaw
of the total nonsolid volume (solid + nonsolid) of a unit
depth and are best determined before serial testing by making
quantity of material.
trial measurements. Care is taken to ensure that the magnitude
3.2.22 sandwich core material—an engineered part, article,
of the applied load is acceptably below the damage threshold of
or structure made up of two or more sheets of composite
a given test article. The applied load can be any of the
laminate, metal, or other material designed to support in-plane
following: heat, mechanical vibration, acoustic vibration, pres-
tensile or compressive loads, separated by and bonded to inner
sure and vacuum, electric fields, magnetic fields, microwave,
core(s) material(s) designed to support normal compressive
or mechanical load.
and tensile loads such as metal or composite honeycomb, open
and closed cell foam, wave formed material, bonded composite 4.3 Shearography NDT systems use a common path
tubes, or naturally occurring material such as end grain balsa Michelson, birefringant, or beam splitter type shearing inter-
wood. ferometer for imaging defects. Some of the most current
E2581 − 14 (2019)
FIG. 2 Shear vector angle convention: Starting with the shear camera adjusted for a 0° shear con
...
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.
Designation: E2581 − 14 E2581 − 14 (Reapproved 2019)
Standard Practice for
Shearography of Polymer Matrix Composites and Sandwich
Core Materials in Aerospace Applications
This standard is issued under the fixed designation E2581; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This practice describes procedures for shearography of polymer matrix composites and sandwich core materials made
entirely or in part from fiber-reinforced polymer matrix composites. The composite materials under consideration typically contain
continuous high modulus (greater than 20 GPa (3×106 psi)) 20 GPa (3×106 psi)) fibers, but may also contain discontinuous fiber,
fabric, or particulate reinforcement.
1.2 This practice describes established shearography procedures that are currently used by industry and federal agencies that
have demonstrated utility in quality assurance of polymer matrix composites and sandwich core materials during product process
design and optimization, manufacturing process control, after manufacture inspection, and in service inspection.
1.3 This practice has utility for testing of polymer matrix composites and sandwich core materials containing but not limited
to bismaleimide, epoxy, phenolic, poly(amideimide), polybenzimidazole, polyester (thermosetting and thermoplastic), poly(ether
ether ketone), poly(ether imide), polyimide (thermosetting and thermoplastic), poly(phenylene sulfide), or polysulfone matrices;
and alumina, aramid, boron, carbon, glass, quartz, or silicon carbide fibers. Typical as-fabricated geometries include uniaxial,
cross-ply and angle-ply laminates; as well as honeycomb and foam core sandwich materials and structures.
1.4 This practice does not specify accept-reject criteria and is not intended to be used as a means for approving polymer matrix
composites or sandwich core materials for service.
1.5 To ensure proper use of the referenced standards, there are recognized nondestructive testing (NDT) specialists that are
certified according to industry and company NDT specifications. It is recommended that an NDT specialist be a part of any
composite component design, quality assurance, in-service maintenance, or damage examination activity.
1.6 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.
1.7 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:
C274 Terminology of Structural Sandwich Constructions (Withdrawn 2016)
D3878 Terminology for Composite Materials
D5687/D5687M Guide for Preparation of Flat Composite Panels with Processing Guidelines for Specimen Preparation
E543 Specification for Agencies Performing Nondestructive Testing
E1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in Databases (Withdrawn 2015)
E1316 Terminology for Nondestructive Examinations
This practice 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 Oct. 1, 2014Dec. 1, 2019. Published December 2014January 2020. Originally approved in 2007. Last previous edition approved in 2014 as
E2581-07.– 14. DOI: 10.1520/E2581-14.10.1520/E2581-14R19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. 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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2581 − 14 (2019)
E1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases (Withdrawn 2015)
E1471 Guide for Identification of Fibers, Fillers, and Core Materials in Computerized Material Property Databases (Withdrawn
2015)
E2533 Guide for Nondestructive Testing of Polymer Matrix Composites 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 Standards:
SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing
ANSI/ASNT CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel
2.3 AIA Document:
NAS-410 Certification and Qualification of Nondestructive Test Personnel
2.4 BSI Document:
EN 60825-1 Safety of Laser Products - Part 1: Equipment Classification, Requirements, and User’s Guide
2.5 LIA Document:
ANSI Z136.1-2000 Safe Use of Lasers
2.6 Federal Standards:
21 CFR 1040.10 Laser products
21 CFR 1040.11 Specific purpose laser products
29 CFR 1910.95 Occupational Noise Exposure
3. Terminology
3.1 Definitions—Definition of terms related to structural sandwich constructions, NDT, and composites appearing in
Terminologies C274, E1316, and D3878, respectively, shall apply to the terms used in this standard.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 aerospace—any component that will be installed on a system that flies.
3.2.2 beam splitter—an optical element capable of splitting a single beam of coherent laser light into two beams. Beam splitters
are key elements of Michelson Type Image Shearing Interferometers.
FIG. 1 Schematic diagram of a Michelson type shearing interferometer shown with a shearography calibration device consisting of a
metal plate with a machined flat bottomed hole creating a deformable plate with a precision mechanical mechanism for loading at the
center point.
Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http://www.aia-aerospace.org.
Available from British Standards Institution (BSI), 389 Chiswick High Rd., London W4 4AL, U.K., http://www.bsigroup.com.
Available from the Laser Institute of America, 13501 Integrity Drive, Suite 128, Orlando FL 32826.
Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
www.access.gpo.gov.
E2581 − 14 (2019)
3.2.3 cognizant engineering organization—the company, agency, or other authority responsible for the design or after delivery,
end use of the system or component for which laser holographic or laser shearographic examination is required; in addition to
design personnel, this may include personnel from material and process engineering, stress anaylsis, NDT, or quality groups and
others as appropriate.
3.2.4 coherent light source—a light source that converts electrical energy to a monochromatic beam of light having uniform
phase over a minimum specified length known as the coherent length.
3.2.5 component—the part(s) or element(s) of a system described, assembled, or processed to the extent specified by the
drawing.
3.2.6 composite material—see Terminology D3878.
3.2.7 composite component—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.
3.2.8 core crush—a collapse, distortion, or compression of core material in a sandwich structure.
3.2.9 core separation—a partial or complete breaking of honeycomb core node bonds.
3.2.10 disbond, unbond —see Terminology D3878.
3.2.11 de-correlation—loss of shearography phase data caused by test part deformation exceeding the resolution of the shearing
interferometer or motion occurs between the test object and shearing interferometer during data acquisition.
3.2.12 delamination—see Terminology D3878.
3.2.13 displacement derivatives (∂w/∂x)— rate of spatial displacement change, where w is the surface displacement and x is the
surface coordinates.
3.2.14 fringe pattern—a set of lines in a subtraction or wrapped phase shearogram that represents the locus of equal out-of-plane
deformation derivative.
3.2.15 impact damage—fracturing of epoxy matrix, fiber breakage, inter-laminar delamination of monolithic composites,
composite sandwich structure face sheets due to impact, characterized by visible dimple surface compression, or fiber breakage
caused by impact strike and non-visible subsurface matrix cracking and delamination.
3.2.16 inclusion—foreign objects or material including but not limited to particles, chips, backing films, razor blades, or tools
of varying sizes which are inadvertently left in a composite lay-up.
3.2.17 indication—the observation or evidence of a condition resulting from the shearographic examination that requires
interpretation to determine its significance, characterized by dimensions, area, s/n ratio, or other quantitative measurement.
3.2.18 laser shearography inspection, shearography inspection, shearography—inspection method utilizing interferometric
imaging of deformation derivatives compared between different strain states and designed to reveal non-homogeneities, material
changes and structural defects throughout the volume of the material.
3.2.19 out-of-plane displacement—the local deformation of a test part, normal to the surface, caused by the application of an
engineered force acting on a non-homogeneity or defect in a composite material.
3.2.20 polymer matrix composite—any fiber-reinforced composite lay-up consisting of laminae (plies) with one or more
orientations with respect to some reference direction that are consolidated by press, vacuum bagging, or autoclave to yield an
engineered part article or structure.
3.2.21 porosity—condition of trapped pockets of air, gas, or void within solid materials, usually expressed as a percentage of
the total nonsolid volume (solid + nonsolid) of a unit quantity of material.
3.2.22 sandwich core material—an engineered part, article, or structure made up of two or more sheets of composite laminate,
metal, or other material designed to support in-plane tensile or compressive loads, separated by and bonded to inner core(s)
material(s) designed to support normal compressive and tensile loads such as metal or composite honeycomb, open and closed cell
foam, wave formed material, bonded composite tubes, or naturally occurring material such as end grain balsa wood.
3.2.23 scan plan—a designed sequence of steps for positioning and adjusting a shearography camera to accomplish a desired
inspection. Scan plans shall include camera field of view, percentage of image overlap, position sequences for each area to be
tested, test number, and location in a coordinate system appropriate for test object geometry and access.
3.2.24 shearogram—the resulting image from the complex arithmetic combination of interferograms made with an image
shearing interferometer and presented for interpretation in various image processing algorithms including wrapped phase maps
(static or real-time), unwrapped phase maps, integrated, Doppler shift map.
3.2.25 shearography camera, shear camera—an image shearing interferometer used for shearography nondestructive testing,
usually including features for adjustment of focus, iris, zoom, shear vector, and projection and adjustment of coherent light onto
the test object area to be inspected.
E2581 − 14 (2019)
3.2.26 shear vector—the separation vector between two identical images of the target in the output of an image shearing
interferometer. The Shear vector is expressed in degrees of angle from the X axis, with a maximum of 90°, with + being in the
positive Y direction and – in the negative Y direction. The shear distance between identical points in the two sheared images
expressed in inches or mm. (See Fig. 2 shear vector angle convention).
3.2.27 stressing device—the means to apply a measurable and repeatable engineered stress to the test object during shearography
inspection. The applied stress may be in the form of a partial vacuum, pressure, heat, vibration, magnetic field, electric field,
microwave, or mechanical load. Also referred to as excitation or excitation method.
3.2.28 void—an empty, unoccupied space in laminate. Voids are associated with bridging and resin starved areas.
4. Summary of Practice
4.1 Shearography nondestructive inspection refers to the use of an image shearing interferometer to image local out-of-plane
deformation derivatives on the test part surface in response to a change in the applied engineered load. Shearography images tend
to show only the local deformation on the target surface due to the presence of a surface or subsurface flaw, delaminations, core
damage, or core splice joint separations, as well as impact damage.
4.2 Typical applied loads to the test part are dependant on the test part material reaction to the induced load. The optimum load
type and magnitude depend on the flaw type and flaw depth and are best determined before serial testing by making trial
measurements. Care is taken to ensure that the magnitude of the applied load is acceptably below the damage threshold of a given
test article. The applied load can be any of the following: heat, mechanical vibration, acoustic vibration, pressure and vacuum,
electric fields, magnetic fields, microwave, o
...
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