ASTM D3878-07(2013)
(Terminology)Standard Terminology for Composite Materials
Standard Terminology for Composite Materials
SCOPE
1.1 These definitions cover generic terms, including terms of commercial importance, that appear in one or more standards on composites containing high-modulus (greater than 20-GPa (3 × 10 6 psi)) fibers.
1.2 The definitions cover, in most cases, special meanings used in the composites industry. No attempt has been made to include common meanings of the same terms as used outside the composites industry.
1.3 Definitions included have, in general, been approved as standard.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D3878 − 07(Reapproved 2013)
Standard Terminology for
Composite Materials
This standard is issued under the fixed designation D3878; 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 braided fabric—see braided fabric under fabric.
1.1 These definitions cover generic terms, including terms
breather string, n—a string, composed of a material such as
of commercial importance, that appear in one or more stan-
glass, that provides a vacuum path from the laminate to a
dards on composites containing high-modulus (greater than
breather.
20-GPa (3×10 psi)) fibers.
bundle—a general term for a collection of essentially parallel
1.2 The definitions cover, in most cases, special meanings
filaments.
used in the composites industry. No attempt has been made to
include common meanings of the same terms as used outside
carbon fiber precursor—a material from which carbon fiber
the composites industry. ismadebypyrolysis.Polyacrylonitrile,rayon,orpitchfibers
are commonly used precursors.
1.3 Definitions included have, in general, been approved as
standard.
catenary:
filament catenary—the difference in length of the filaments
2. Referenced Documents
inaspecifiedlengthoftow,end,orstrandasaresultofunequal
2.1 ASTM Standards:
tension; the tendency of some filaments in a taut horizontal
D123Terminology Relating to Textiles
tow, end, or strand to sag lower than others.
2.2 Military Standard:
roving catenary—the difference in length of the ends, tows,
MIL-HDBK-17
or strands in a specified length of roving as a result of unequal
tension; the tendency of some ends, tows, or strands in a taut
3. Terminology
horizontal roving to sag lower than others.
3.1 Definitions:
645° laminate—a balanced symmetric laminate composed of caul, n—aflatorcontouredtoolusedtodistributepressureand
todefineasurfaceforthetopofthelaminateduringlaminate
only +45° plies and −45° plies.
consolidation or cure.
angleply laminate—any balanced laminate consisting of plus
and minus theta plies where theta is an acute angle with co-fabrication, n—in sandwich constructions, a fabrication
respect to a reference direction. process where items such as inserts and other structural
details are bonded into the panel at the same time that the
balanced laminate—any laminate that contains one ply of
facings are bonded to the core.
minusthetaorientationwithrespecttothelaminateprincipal
axis for every identical ply with a plus theta orientation. composite:
composite material—a substance consisting of two or more
materials, insoluble in one another, which are combined to
This terminology is under the jurisdiction of ASTM Committee D30 on
form a useful engineering material possessing certain proper-
Composite Materials and is the direct responsibility of Subcommittee D30.01 on
Editorial and Resource Standards.
ties not possessed by the constituents.
Current edition approved May 1, 2013. Published May 2013. Originally
DISCUSSION—a composite material is inherently inhomogeneous on a
approved in 1981. Last previous edition approved in 2007 as D3878–07. DOI:
microscopic scale but can often be assumed to be homogeneous on a
10.1520/D3878-07R13.
macroscopic scale for certain engineering applications. The constitu-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ents of a composite retain their identities: they do not dissolve or
contactASTM Customer Service at service@astm.org. ForAnnual Book ofASTM
otherwise merge completely into each other, although they act in
Standards volume information, refer to the standard’s Document Summary page on
concert.
the ASTM website.
Available from ASTM International as The Composite Materials Handbook—
discontinuous fiber-reinforced composite— any composite
MIL 17. Also available as MIL-HDBK-17 from Standardization Documents Order
material consisting of a matrix reinforced by discontinuous
Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-
5094 fibers. The fibers may be whiskers or chopped fibers.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3878 − 07 (2013)
level of the performance parameter increases for a given damage size.
fabric-reinforced composite—any composite material con-
Damage tolerance depends upon the type of loading which is applied.
sisting of a matrix reinforced by fabric (woven, knitted, or
For example, the damage tolerance for a compressive load can be, and
braided assemblages of fibers).
generally is, different than for the same level of tensile load.
fiber-reinforced composite—any composite material consist-
Damage resistance is often confused with damage tolerance. Dam-
age tolerance is directly related only to the size and type of damage
ing of a matrix reinforced by continuous or discontinuous
whilebeingonlyindirectlyrelatedtohowthedamagewascreated(see
fibers.
damage resistance). Thus, damage tolerance is distinct from damage
filamentary composite—a composite material reinforced
resistance.
with continuous fibers.
debond—adeliberateseparationofabondedjointorinterface,
unidirectional fiber-reinforced composite— any fiber-
usually for repair or rework purposes.
reinforced composite with all fibers aligned in a single direc-
debulk, v—to decrease voids between lamina before laminate
tion.
consolidation through use of vacuum or by mechanical
continuous filament yarn, n—two or more continuous fila-
means.
ments twisted into a single fiber bundle.
DISCUSSION—Laminae can be debulked at ambient or elevated
temperatures.
crossply laminate—a laminate composed of only 0 and 90°
plies. This is not necessarily symmetric.
delamination—separation of plies in a laminate. This may be
local or may cover a large area in the laminate.
dam, n—a solid material (such as silicone rubber, steel, or
aluminum), used in processing composites, to contain the denier, n—a direct numbering system for expressing linear
matrix material within defined boundaries or to prevent
density, equal to the mass in grams per 9000 metres of yarn,
crowning of a processing bag.
filament, fiber, or other textile strand.
damage, n—in structures and structural mechanics, a struc- disbond—an area within a bonded interface between two
tural anomaly in material or structure created by manufac- adherents in which an adhesive or cohesive failure has
turing or service usage. occurred. It may occur at any time during the life of the
structure and may arise from a wide variety of causes. It is
damage resistance, n— in structures and structural
sometimes used to describe an area of separation between
mechanics, a measure of the relationship between the force,
two laminae in the finished laminate (the term “delamina-
energy, or other parameter(s) associated with an event or
tion” is preferred).
sequence of events and the resulting damage size and type.
DISCUSSION—Damage resistance increases as the force, energy, or discontinuous fiber—a polycrystalline or amorphous fiber
other parameter increases for a given size or type of damage.
thatisdiscontinuouswithinthesampleorcomponentorthat
Conversely, damage resistance increases as damage decreases, for a
has one or both ends inside of the stress field under
given applied force, energy, or other parameter. Damage resistance and
consideration. The minimum diameter of a discontinuous
damage tolerance are often confused.Amaterial or structure with high
fiber is not limited, but the maximum diameter may not
damage resistance will incur less physical damage from a given event.
exceed 0.25 mm (0.010 in.).
Materials or structures with high damage tolerance may incur varying
levels of physical damage but will have high amounts of remaining
end, n—in fibrous composites,ageneraltermforacontinuous,
functionality.Adamage-resistantmaterialorstructuremay,ormaynot,
ordered assembly of essentially parallel, collimated
be considered damage tolerant.
filaments, with or without twist.
damage tolerance, n—1) in structures and structure materials,
DISCUSSION—This term covers tow, strand, sliver, yarn, and roving.
a measure of the relationship between damage size and type The relationship between fiber form terms is shown in Table X1.1.
andthelevelofaperformanceparameter,suchasstiffnessor
fabric—a planar textile (Synonym: cdth)
strength, at which the structure or structural material can
braided fabric, n—aclothconstructedbyabraidingprocess.
operate for a particular loading condition; 2) in structural
systems,ameasureoftheabilityofsuchsystemstofunction
knitted fabric, n—a cloth constructed by a knitting process.
at designated performance parameters (for example,
nonwoven fabric, n—a cloth constructed by bonding or
magnitude, length of time, and type of loading(s)) without
interlocking, or both (but not interlacing) fiber by any combi-
system failure in the presence of a particular or specified
nation of mechanical, chemical, thermal, or solvent means.
level of damage.
plied yarn, n—a yarn formed by twisting together two or
DISCUSSION—Damage tolerance involves, and can be provided by, a
more single yarns in one operation.
number of factors operating at a number of levels: structural material,
DISCUSSION—Plying,whichisdoneintheoppositedirectionfromthe
structural, and overall system. These factors include 1) basic material
twist of each of the simple yarns, serves to counter the tendency of
ability to operate with damage present (often referred to as the residual
simple yarns to untwist.
strength aspect), 2) damage growth resistance and containment pro-
vided by material and structural considerations, and 3) system inspec-
woven fabric, n—a cloth constructed by a weaving process.
tionandmaintenanceplanswhichallowthedamagetobedetectedand
corrected and which depend upon material, structural, and operational
fabrication, n—the process of manufacturing, forming,
considerations.
constructing, or assembling a product or component.
Damagetoleranceincreasesasthedamagesizeincreasesforagiven
level of a performance parameter. Damage tolerance increases as the fiber, n—one or more filaments in an ordered assemblage.
D3878 − 07 (2013)
DISCUSSION—There are a number of general and specific terms that
intralaminar—describingobjects(forexample,voids),events
definespecifictypesoffiberforms.Therelationshipbetweenfiberform
(for example, fracture), or fields (for example, stress) within
terms is shown in Table 1.
the laminae of a laminate.
fiber content—the amount of fiber present in a composite
knit—atextileprocessthatinterlocks,inaspecificpatternloop
expressed either as percent by weight or percent by volume.
of yarn by means of needles or wires.
This is sometimes stated as a fraction, that is, fiber volume
fraction.
knitted fabric—See knitted fabric under fabric.
fiber volume fraction—see fiber content.
lamina—a subunit of a laminate consisting of one or more
adjacentpliesofthesamematerialwithidenticalorientation.
filament, n—a fibrous form of matter with an aspect ratio >10
and an effective diameter <1 mm. (See also monofilament.)
lamina orientation—same as ply orientation.
DISCUSSION—Filaments may be essentially continuous (aspect ratio
ontheorderof10 orlarger)ordiscontinuous.Whiskersarethespecial
laminate—anyfiber-orfabric-reinforcedcompositeconsisting
case of single crystal discontinuous filaments.
oflaminae(plies)withoneormoreorientationswithrespect
filament count—number of filaments in the cross section of a to some reference direction.
fiber bundle.
laminate coordinate axes—a set of coordinate axes, usually
fill, n—in a woven fabric, the yarn running from selvage to
right-handed Cartesian, used as reference in describing the
selvage at right angles to the warp. MIL-HDBK-17
directional properties and geometrical structure of the lami-
nate. Usually the x-axis and the y-axis lie in the plane of the
filler—in composite materials, a primarily inert solid constitu-
laminate and the x-axis is the reference axis from which ply
entaddedtothematrixtomodifythecompositepropertiesor
angle is measured.
to lower cost.
laminate midplane—the plane that is equidistant from both
float, n—in woven fabric, the portion of a warp (or fill) yarn
surfaces of the laminate.
that extends unbound over two ro more fill (or warp) yarns.
D123
laminate principal axis—the laminate coordinate axis that
coincides with the direction of maximum inplane Young’s
gel time, n—in thermosetting polymers, the period of time
modulus.
from a predetermined starting point to the onset of gelation
as determined by a specific test method.
lay-up, n—(1) the stack of plies in specified sequence and
orientation before cure or consolidation; (2) the complete
hybrid—(for composite materials) containing at least two
distinct types of matrix or reinforcement. Each matrix or stackofplies,baggingmaterial,breathermaterial,andsoon
before cure or consolidation; and (3) a description of the
reinforcement type can be distinct because of its a) physical
or mechanical properties, or both, b) material form, or c) component materials, geometry, and so on of a laminate.
chemical composition.
lay-up, v—to stack plies of material in specified sequence and
interlaminar—describing objects (for example, voids), events
orientation.
(for example, fracture), or fields (for example, stress) be-
lay-up code—a designation system for abbreviating the stack-
tween the laminae of a laminate.
ing sequence of laminated composites.
mandrel—a form, fixture, or male mold used as the base for
TABLE 1 Fiber Forms
production of a part in processes such as lay-up or filament
Continuous Filaments Discontinuous Filaments winding.
Little
Little or
Twist Twisted Twisted or No
material form—the contour, arrangement, and structure of an
No Twist
Twist
unconsolidatedcompositematerial,especiallywithregardto
A B C D
Tow, * P — —
the geometry and nature of the reinforcement. Factors
strand,
sliver
considered part of the material form include, but are not
Single P* P —
limitedto:reinforcementdiameter,reinforcementlength(for
yarn
discontinuous reinforcements), tow size or count, fabric
Plied P— P —
yarn
areal weight, fabric style, reinforcement content, and ply
E
Roving *P — —
thickness.
end (generic term that can be applied to any of the above)
Chopped —— — P
matrix, n—thecontinuousconstituentofacompositematerial,
fiber
Whisker — — (single crystal)
which surrounds or engulfs embedded filler or reinforce-
A
Small filament count. ment.
B
*—Secondary/alternate definition.
C
P—primary/preferred definition.
matr
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.