ASTM D5687/D5687M-95(2007)
(Guide)Standard Guide for Preparation of Flat Composite Panels with Processing Guidelines for Specimen Preparation
Standard Guide for Preparation of Flat Composite Panels with Processing Guidelines for Specimen Preparation
SIGNIFICANCE AND USE
The techniques described in this guide, if properly used in conjunction with a knowledge of behavior of particular material systems, will aid in the proper preparation of consolidated laminates for mechanical property testing.
The techniques described are recommended to facilitate the consistent production of satisfactory test specimens by minimizing uncontrolled processing variance during specimen fabrication.
Steps 3 through 8 of the 8-step process may not be required for particular specimen or test types. If the specimen or test does not require a given step in the process of specimen fabrication, that particular step may be skipped.
A test specimen represents a simplification of the structural part. The test specimen’value lies in the ability of several sites to be able to test the specimen using standard techniques. Test data may not show identical properties to those obtained in a large structure, but a correlation can be made between test results and part performance. This may be due, in part, to the difficulty of creating a processing environment for test specimens that identically duplicates that of larger scale processes.
Tolerances are guidelines based on current lab practices. This guide does not attempt to give detailed instructions due to the variety of possible panels and specimens that could be made. The tolerances should be used as a starting reference from which refinements can be made.
SCOPE
1.1 This guide provides guidelines to facilitate the proper preparation of laminates and test specimens from fiber-reinforced organic matrix composite prepregs. The scope is limited to organic matrices and fiber reinforcement in unidirectional (tape) or orthagonal weave patterns. Other forms may require deviations from these general guidelines. Other processing techniques for test coupon preparation, for example, pultrusion, filament winding and resin-transfer molding, are not addressed.
1.2 Specimen preparation is modeled as an 8-step process that is presented in and Section . Laminate consolidation techniques are assumed to be by press or autoclave. This practice assumes that the materials are properly handled by the test facility to meet the requirements specified by the material supplier(s) or specification, or both. Identification and information gathering guidelines are modeled after Guide E 1309. Test specimens shall be directly traceable to material used as designated in Guide E 1434. Proper test specimen identification also includes designation of process equipment, process steps, and any irregularities identified during processing.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text the inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: D5687/D5687M − 95(Reapproved 2007)
Standard Guide for
Preparation of Flat Composite Panels with Processing
Guidelines for Specimen Preparation
This standard is issued under the fixed designation D5687/D5687M; 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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This guide provides guidelines to facilitate the proper
C297/C297MTest Method for Flatwise Tensile Strength of
preparation of laminates and test specimens from fiber-
Sandwich Constructions
reinforced organic matrix composite prepregs. The scope is
D123Terminology Relating to Textiles
limited to organic matrices and fiber reinforcement in unidi-
D792Test Methods for Density and Specific Gravity (Rela-
rectional(tape)ororthagonalweavepatterns.Otherformsmay
tive Density) of Plastics by Displacement
require deviations from these general guidelines. Other pro-
D883Terminology Relating to Plastics
cessing techniques for test coupon preparation, for example,
D2734TestMethodsforVoidContentofReinforcedPlastics
pultrusion, filament winding and resin-transfer molding, are
D3163Test Method for Determining Strength ofAdhesively
not addressed.
Bonded Rigid Plastic Lap-Shear Joints in Shear by Ten-
1.2 Specimen preparation is modeled as an 8-step process sion Loading
that is presented in Fig. 1 and Section 8. Laminate consolida-
D3171Test Methods for Constituent Content of Composite
tion techniques are assumed to be by press or autoclave. This Materials
practiceassumesthatthematerialsareproperlyhandledbythe D3531Test Method for Resin Flow of Carbon Fiber-Epoxy
test facility to meet the requirements specified by the material Prepreg
supplier(s) or specification, or both. Identification and infor- D3878Terminology for Composite Materials
D3990Terminology Relating to Fabric Defects
mation gathering guidelines are modeled after Guide E1309.
Test specimens shall be directly traceable to material used as D4850Terminology Relating to Fabrics and Fabric Test
Methods
designatedinGuideE1434.Propertestspecimenidentification
D5229/D5229MTestMethodforMoistureAbsorptionProp-
also includes designation of process equipment, process steps,
erties and Equilibrium Conditioning of Polymer Matrix
and any irregularities identified during processing.
Composite Materials
1.3 The values stated in either SI units or inch-pound units
E1237Guide for Installing Bonded Resistance Strain Gages
are to be regarded separately as standard. Within the text the
E1309 Guide for Identification of Fiber-Reinforced
inch-pound units are shown in brackets. The values stated in
Polymer-Matrix Composite Materials in Databases
each system are not exact equivalents; therefore, each system
E1434Guide for Recording Mechanical Test Data of Fiber-
must be used independently of the other. Combining values
Reinforced Composite Materials in Databases
from the two systems may result in nonconformance with the
standard.
3. Terminology
1.4 This standard does not purport to address all of the 3.1 Definitions—Terminology D3878 defines terms relating
safety concerns, if any, associated with its use. It is the
to high-modulus fibers and their composites. Terminology
responsibility of the user of this standard to establish appro- D883 defines terms relating to plastics. Terminology D123
priate safety and health practices and determine the applica- definestextilerelatedterms.TerminologyD4850definesterms
bility of regulatory limitations prior to use. relating to fabric. In the event of a conflict between terms,
Terminology D3878 shall have precedence over the other
standards.
This guide is under the jurisdiction of ASTM Committee D30 on Composite
Materials and is the direct responsibility of Subcommittee D30.04 on Lamina and
Laminate Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2007. Published June 2007. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1995. Last previous edition approved in 2002 as D5687/ Standards volume information, refer to the standard’s Document Summary page on
D5687M-95(2002). DOI: 10.1520/D5687_D5687M-95R07. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5687/D5687M − 95 (2007)
3.2.8 doubler, n—anunbondedtabusedtoholdthelaminate
specimen in a grip or fixture. See tab.
3.2.9 fiber washing, n—the tendency of fibers to change
orientationduetoresinflowfromtheoriginallay-updirection.
Fiber washing may occur during the laminate consolidation
process mainly at the sides of a laminate.
3.2.10 fill, n—(1) Fiber inserted by the shuttle during
weaving also designated as filling. See Terminology D123.(2)
The direction of fiber running perpendicular to the warp fibers.
3.2.11 flip/flop, v—the process of alternating plies through
an angle orientation of 180° during laminate lay-up. This
practice is commonly used if material of the same width as the
laminate has a reoccurring flaw. The process changes the
location of the flaw so that it does not unduly affect the
laminate structure.
3.2.12 flaw, n—a material defect, typically occurring in the
discrete fiber reinforcement, but possible in the matrix.
3.2.13 flow, n—the movement of uncured matrix under
NOTE 1—Material identification is mandatory. Continuous traceability
pressure during laminate consolidation.
of specimens is required throughout the process.
Process checks (Appendix X4) may be done at the end of each step to
3.2.14 harness, n—a weaving designation of how many fill
verify that the step was performed to give a laminate or specimen of
fibersawarpfloatcrossesinasatinweave.Typicalweavesare
satisfactory quality.
Steps 4 and 5 may be interchanged. For aramid fibers, step 5 routinely 5-Harness and 8-Harness.
precedes step 4.
3.2.15 joint, n—alocationwheretwoedgesofprepregmeet.
Steps 6, 7 and 8 may be interchanged.
Two common types of joints used in lay-up are a butt joint
FIG. 1 8 Step Mechanical Test Data Model
(where 2 plies are aligned edge to edge) and an overlap joint
(wheretheedgeofeachplyisoverlappedsomespecifiedwidth
3.2 Description of Trems Used in This Standard—Theterms
with another ply).
usedinthisguidemayconflictwithgeneralusage.Thereisnot
3.2.16 lay-up, n—the finished product of ply stacking and
yetanestablishedconsensusconcerningtheuseoftheseterms.
bagging operations.
The following descriptions are intended only for use in this
guide.
3.2.17 matrix, n—the continuous constituent of a composite
3.2.1 bag, v—the process of enclosing the ply layers within
material.
a flexible container. See lay-up.
3.2.18 mold,n—thesupportstructurethatholdsthelaminate
3.2.2 base plate, n—a flat plate on which a laminate is laid
or lay-up during the laminate consolidation process.
up [usually made of aluminum and 6 mm [0.25 in.] or thicker
3.2.19 non-perforated TFE, n—a non-porous tetrafluoroeth-
with a flatness requirement of 0.05 mm [0.002 in.] or less].
ylene film.
3.2.3 breather string, n—a glass string connected from the
laminate to a breather in the autoclave bag. It is used as a 3.2.20 panel, n—auniformlycontouredcompositelaminate,
degassing aid; providing a path for gasses to be transferred typically flat.
from the laminate.
3.2.21 peel ply, n—a cloth with release capabilities. Usually
3.2.4 caul plate, n—aflatplateusedtoprovideaflatsurface
used in conjunction with laminates requiring secondary bond-
to the top of the laminate during laminate consolidation
ing.
[usually made of aluminum and 3 mm [0.125 in.] thick or
3.2.22 perforated TFE, n—aporoustetrafluoroethylenefilm
thicker with a flatness requirement of 0.05 mm [0.002 in.] or
usedinthebaggingprocessthatallowsgassesorexcessmatrix
less].
materials to escape from a laminate during laminate
3.2.5 cloth, n—a piece of textile fabric containing woven
consolidation, while protecting the laminate from physical
reinforcement without a load transferring matrix.
bonding to other items such as base plates or caul plates.
3.2.6 dam, n—asolidmaterial(suchassiliconerubber,steel
3.2.23 ply, n—a single layer of prepreg used in lay-up.
or aluminum) used in the autoclave bag to contain the matrix
3.2.24 press, n—equipment consisting of heated, flat [usu-
material within defined boundaries during laminate consolida-
allywithinatoleranceof0.3mm[0.01in.]orless]platensthat
tion.
supply pressure against a surface.
3.2.7 debulk, v—process of decreasing voids between
laminabeforelaminateconsolidationthroughuseofvacuumor 3.2.25 satin, adj—aweavepatterninwhichwarpfloatspass
by mechanical means. Laminae can be debulked at ambient or over several yarns before crossing under a single yarn. It is
elevated temperatures. characterized by parallel fibers and no diagonal pattern.
D5687/D5687M − 95 (2007)
3.2.26 sealant, n—a high temperature material used to seal 5.3 Steps 3 through 8 of the 8-step process may not be
the edges of a vacuum bag to the base plate during a required for particular specimen or test types. If the specimen
consolidation or debulking cycle. or test does not require a given step in the process of specimen
fabrication, that particular step may be skipped.
3.2.27 staggered, adj—the description of ply placement
wherethejointsarenotpositionedinthesameinplanelocation
5.4 A test specimen represents a simplification of the
through some specified thickness of the laminate.
structural part. The test specimen’s value lies in the ability of
several sites to be able to test the specimen using standard
3.2.28 tab, n—a piece of material used to hold the laminate
techniques. Test data may not show identical properties to
specimen in a grip or fixture for testing so that the laminate is
those obtained in a large structure, but a correlation can be
not damaged, and is adequately supported. It is bonded to the
made between test results and part performance. This may be
specimen. An unbonded tab is termed a doubler.
due, in part, to the difficulty of creating a processing environ-
3.2.29 TFE coated cloth, n—a cloth coated with a tetrafluo-
mentfortestspecimensthatidenticallyduplicatesthatoflarger
roethylenecoating.Thisisusedinthebaggingprocesstoallow
scale processes.
gases or excess matrix material to escape during the laminate
5.5 Tolerancesareguidelinesbasedoncurrentlabpractices.
consolidation. It differs from perforated TFE in that it gives a
Thisguidedoesnotattempttogivedetailedinstructionsdueto
textured surface to the laminate.
the variety of possible panels and specimens that could be
3.2.30 traveler, n—a coupon with the same nominal thick-
made. The tolerances should be used as a starting reference
nessandwidthasthetestspecimen,madeofthesamematerial
from which refinements can be made.
andprocessedsimilarlytothespecimenexceptusuallywithout
tabs or gages. The traveler is used to measure mass changes
6. Interferences
during environmental conditioning when it is impractical to
6.1 Specimenpreparationpracticesshouldreflectthoseused
measure these changes on the actual specimen.
onanapplicablepart,tothegreatestextentpractical.However,
3.2.31 vacuum bag, n—a low gas permeable material used
due to scaling effects, processing requirements for test lami-
to enclose and seal the laminate during a consolidation or
nates may not exactly duplicate the processes used in larger
debulking cycle.
scale components. The user should attempt to understand and
3.2.32 vacuum couple, n—the mechanical connection that
control those critical process parameters that may produce a
sealsthevacuumsourcetothelay-upduringaconsolidationor
differenceinmaterialresponsebetweenthetestcouponandthe
debulking cycle.
structure. Critical process parameters are material, application,
and process dependent and are beyond the scope of this guide.
3.2.33 warp surface, n—the ply surface which shows the
larger area of warp tows with respect to filling tows. Fabrics
6.2 Laminate quality is directly related to the prevention of
where both surfaces show an equal area of warp tows with
contamination during lay-up and processing.
respect to filling tows do not have a warp surface.
7. Apparatus and Materials
3.2.34 warp nested, n—warp plies alternated in the pattern
NOTE1—Thissectionprovidesalistingofapparatusandmaterialitems
warp surface up, warp surface down.
that have been shown to be acceptable. The list is not meant to be all
inclusive, but may be helpful to novice users.
4. Summary of Guide
7.1 Equipment:
4.1 This guide describes the general process flow for prepa-
7.1.1 Lay-up Environment/Tools:
ration of flat composite panels and provides specific recom-
7.1.1.1 Tables—Tables should be1m[3ft]in height (or
mended techniques that are generally suitable to laminated
adjustable tables) with ample area for lay-up.The table should
fibrous organic polymer matrix composites for each of the
be accessible from all sides. The table surface should have a
process steps to test specimen fabrication.
fully supported metal or wood undersurface. The table surface
shouldbeof(1)safetyglasswithedgesprotectedbyaluminum
4.2 The specific techniques included in this guide are the
angle plate or (2) A toughened transparent plastic sheet.
minimum recommended for common composite material sys-
7.1.1.2 Convenient accessibility of lay-up materials—Wall
tems as represented in the scope of this guide. For a given
racks hold bulk cloth, TFE, and other expendable bagging
application other techniques may need to be added or substi-
materials.Theserackstypicallyconsistofasteelrodwhichcan
tuted for those described by this guide.
hold a roll of material. The rods should be able to accommo-
date material rolls up to 1.5 m [60 in.] wide. The spacing
5. Significance and Use
between racks should be a minimum of 0.4 m [15 in.] spacing
5.1 The techniques described in this guide, if properly used
between rods with the bottom rod being no closer than 0.6 m
in conjunction with a knowledge of behavior of particular
[25 in.] to the floor and the top rod being no higher than 2.2 m
material systems, will aid in the proper preparation of consoli-
[85 in.] from the floor. Cabinets and drawers hold other lay-up
dated laminates for mechanical property testing.
materials such as sealants, spare tape, vacuum couples, hoses,
5.2 The techniques described are recommended to facilitate caul plates, thermocouple wire, and so forth. These should be
the consistent production of satisfactory test specimens by compartmentalized for easy access.
minimizing uncontrolled processing variance during specimen 7.1.1.3
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