ASTM D3878-98
(Terminology)Standard Terminology Composite Materials
Standard Terminology 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 X 106 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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3878 – 98
Standard Terminology for
Composite Materials
This standard is issued under the fixed designation D 3878; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope composite material—a substance consisting of two or more
materials, insoluble in one another, which are combined to
1.1 These definitions cover generic terms, including terms
form a useful engineering material possessing certain prop-
of commercial importance, that appear in one or more stan-
erties not possessed by the constituents.
dards on composites containing high-modulus (greater than
20-GPa (3 3 10 psi)) fibers.
DISCUSSION—a composite material is inherently inhomogeneous on a
1.2 The definitions cover, in most cases, special meanings
microscopic scale but can often be assumed to be homogeneous on a
macroscopic scale for certain engineering applications. The constitu-
used in the composites industry. No attempt has been made to
ents of a composite retain their identities: they do not dissolve or
include common meanings of the same terms as used outside
otherwise merge completely into each other, although they act in
the composites industry.
concert.
1.3 Definitions included have, in general, been approved as
standard. damage, n—in structures and structural mechanics, a struc-
tural anomaly in material or structure created by manufac-
2. Terminology
turing or service usage.
2.1 Definitions:
damage resistance, n—in structures and structural mechan-
ics, a measure of the relationship between the force, energy,
645° laminate—a balanced symmetric laminate composed of
or other parameter(s) associated with an event or sequence of
only +45° plies and −45° plies.
events and the resulting damage size and type.
angleply laminate—any balanced laminate consisting of plus
and minus theta plies where theta is an acute angle with DISCUSSION—Damage resistance increases as the force, energy, or
other parameter increases for a given size or type of damage. Con-
respect to a reference direction.
versely, damage resistance increases as damage decreases, for a given
balanced laminate—any laminate that contains one ply of
applied force, energy, or other parameter. Damage resistance and
minus theta orientation with respect to the laminate principal
damage tolerance are often confused. A material or structure with high
axis for every identical ply with a plus theta orientation.
damage resistance will incur less physical damage from a given event.
braided fabric—see braided fabric under fabric.
Materials or structures with high damage tolerance may incur varying
bundle—a general term for a collection of essentially parallel
levels of physical damage but will have high amounts of remaining
functionality. A damage-resistant material or structure may, or may not,
filaments.
be considered damage tolerant.
carbon fiber precursor—a material from which carbon fiber
is made by pyrolysis. Polyacrylonitrile, rayon or pitch fibers
discontinuous fiber-reinforced composite—any composite
are commonly used precursors.
material consisting of a matrix reinforced by discontinuous
catenary:
fibers. The fibers may be whiskers or chopped fibers.
filament catenary—the difference in length of the filaments in
fabric-reinforced composite—any composite material con-
a specified length of tow, end, or strand as a result of unequal
sisting of a matrix reinforced by fabric (woven, knitted, or
tension; the tendency of some filaments in a taut horizontal
braided assemblages of fibers).
tow, end, or strand to sag lower than others.
fiber-reinforced composite—any composite material consist-
roving catenary—the difference in length of the ends, tows, or
ing of a matrix reinforced by continuous or discontinuous
strands in a specified length of roving as a result of unequal
fibers.
tension; the tendency of some ends, tows, or strands in a taut
filament count—number of filaments in the cross section of a
horizontal roving to sag lower than others.
fiber bundle.
composite:
filamentary composite—a composite material reinforced with
continuous fibers.
unidirectional fiber-reinforced composite—any fiber-
These definitions are under the jurisdiction of ASTM Committee D30 on
High-Modulus Fibers and Their Composites and are the direct responsibilities of
reinforced composite with all fibers aligned in a single
Subcommittee D30.01 on Editorial and Terminology.
direction.
Current edition approved Dec. 10, 1998. Published February 1999. Originally
crossply laminate—a laminate composed of only 0 and 90°
published as D 3878 – 81. Last previous edition D 3878 – 95c.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 3878
TABLE 1 Fiber Forms
plies. This is not necessarily symmetric.
debond—a deliberate separation of a bonded joint or interface, Discontinuous
Continuous Filaments
Filaments
usually for repair or rework purposes.
Little Little
delamination—separation of plies in a laminate. This may be
or or
Twist Twisted Twisted
local or may cover a large area in the laminate. No No
Twist Twist
disbond—an area within a bonded interface between two
A B C D
Tow, * P — —
adherents in which an adhesive or cohesive failure has
strand,
sliver
occurred. It may occur at any time during the life of the
Single P*P —
structure and may arise from a wide variety of causes. It is
yarn
sometimes used to describe an area of separation between
Plied P— P—
yarn
two laminae in the finished laminate (the term “delamina-
E
Roving *P — —
tion” is preferred).
end (generic term that can be applied to any of the
discontinuous fiber—a polycrystalline or amorphous fiber
above)
Chopped——— P
that is discontinuous within the sample or component or that
fiber
has one or both ends inside of the stress field under
Whisker — — (single crystal)
consideration. The minimum diameter of a discontinuous
A
Small filament count.
fiber is not limited, but the maximum diameter may not B
*—Secondary/alternate definition.
C
P—primary/preferred definition.
exceed 0.25 mm (0.010 in.).
D
—not applicable.
end, n—in fibrous composites, a general term for a continuous,
E
Large filament count.
ordered assembly of essentially parallel, collimated fila-
ments, with or without twist.
or mechanical properties, or both, b) material form, or c)
DISCUSSION—This term covers tow, strand, sliver, yarn, and roving.
chemical composition.
The relationship between fiber form terms is shown in Table X1.1.
interlaminar—describing objects (for example, voids), events
fabric—a planar textile (Synonym: cdth) (for example, fracture), or fields (for example, stress) be-
tween the laminae of a laminate.
braided fabric, n—a cloth constructed by a braiding process.
knitted fabric, n—a cloth constructed by a knitting process. intralaminar—describing objects (for example, voids), events
(for example, fracture), or fields (for example, stress) within
nonwoven fabric, n—a cloth constructed by bonding or
interlocking, or both (but not interlacing) fiber by any the laminae of a laminate.
knit—a textile process that interlocks, in a specific pattern loop
combination of mechanical, chemical, thermal, or solvent
means. of yarn by means of needles or wires.
knitted fabric—See knitted fabric under fabric.
plied yarn, n—a yarn formed by twisting together two or more
single yarns in one operation. lamina—a subunit of a laminate consisting of one or more
adjacent plies of the same material with identical orientation.
DISCUSSION—Plying, which is done in the opposite direction from the
lamina orientation—same as ply orientation.
twist of each of the simple yarns, serves to counter the tendency of
laminate—any fiber- or fabric-reinforced composite consisting
simple yarns to untwist.
of laminae (plies) with one or more orientations with respect
woven fabric, n—a cloth constructed by a weaving process.
to some reference direction.
fiber, n—one or more filaments in an ordered assemblage.
laminate coordinate axes—a set of coordinate axes, usually
right-handed Cartesian, used as reference in describing the
DISCUSSION—There are a number of general and specific terms that
define specific types of fiber forms. The relationship between fiber form directional properties and geometrical structure of the lami-
terms is shown in Table 1.
nate. Usually the x-axis and the y-axis lie in the plane of the
laminate and the x-axis is the reference axis from which ply
fiber content—the amount of fiber present in a composite
angle is m
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