ASTM D7136/D7136M-05
(Test Method)Standard Test Method for Measuring the Damage Resistance of a Fiber-Reinforced Polymer Matrix Composite to a Drop-Weight Impact Event
Standard Test Method for Measuring the Damage Resistance of a Fiber-Reinforced Polymer Matrix Composite to a Drop-Weight Impact Event
SCOPE
1.1 This test method covers the damage resistance of multidirectional polymer matrix composite laminated plates subjected to a drop-weight impact event. The composite material forms are limited to continuous-fiber reinforced polymer matrix composites, with the range of acceptable test laminates and thicknesses defined in .
1.2 A flat, rectangular composite plate is subjected to an out-of-plane, concentrated impact using a drop-weight device with a hemispherical impactor. The potential energy of the drop-weight, as defined by the mass and drop height of the impactor, is specified prior to test. Equipment and procedures are provided for optional measurement of contact force and velocity during the impact event. The damage resistance is quantified in terms of the resulting size and type of damage in the specimen.
1.3 The test method may be used to screen materials for damage resistance, or to inflict damage into a specimen for subsequent damage tolerance testing. When the impacted plate is tested in accordance with Test Method D 7137/D 7137M, the overall test sequence is commonly referred to as the Compression After Impact (CAI) method. Quasi-static indentation per Test Method D 6264 may be used as an alternate method of creating damage from an out-of-plane force and measuring damage resistance properties.
1.4 The damage resistance properties generated by this test method are highly dependent upon several factors, which include specimen geometry, layup, impactor geometry, impactor mass, impact force, impact energy, and boundary conditions. Thus, results are generally not scalable to other configurations, and are particular to the combination of geometric and physical conditions tested.
1.5 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.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D7136/D7136M–05
Standard Test Method for
Measuring the Damage Resistance of a Fiber-Reinforced
Polymer Matrix Composite to a Drop-Weight Impact Event
This standard is issued under the fixed designation D 7136/D 7136M; 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.
1. Scope must be used independently of the other. Combining values
from the two systems may result in nonconformance with the
1.1 This test method covers the damage resistance of
standard.
multidirectional polymer matrix composite laminated plates
1.6 This standard does not purport to address all of the
subjected to a drop-weight impact event. The composite
safety concerns, if any, associated with its use. It is the
material forms are limited to continuous-fiber reinforced poly-
responsibility of the user of this standard to establish appro-
mer matrix composites, with the range of acceptable test
priate safety and health practices and determine the applica-
laminates and thicknesses defined in 8.2.
bility of regulatory limitations prior to use.
1.2 A flat, rectangular composite plate is subjected to an
out-of-plane, concentrated impact using a drop-weight device
2. Referenced Documents
with a hemispherical impactor. The potential energy of the
2.1 ASTM Standards:
drop-weight, as defined by the mass and drop height of the
D 792 TestMethodsforDensityandSpecificGravity(Rela-
impactor, is specified prior to test. Equipment and procedures
tive Density) of Plastics by Displacement
are provided for optional measurement of contact force and
D 883 Terminology Relating to Plastics
velocity during the impact event. The damage resistance is
D 3171 Test Methods for Constituent Content of Composite
quantified in terms of the resulting size and type of damage in
Materials
the specimen.
D 3763 Test Method for High Speed Puncture Properties of
1.3 The test method may be used to screen materials for
Plastics using Load and Displacement Sensors
damage resistance, or to inflict damage into a specimen for
D 3878 Terminology for Composite Materials
subsequent damage tolerance testing. When the impacted plate
D 5229/D 5229M Test Method for Moisture Absorption
istestedinaccordancewithTestMethodD 7137/D 7137M,the
Properties and Equilibrium Conditioning of Polymer Ma-
overall test sequence is commonly referred to as the Compres-
trix Composite Laminates
sion After Impact (CAI) method. Quasi-static indentation per
D 5687/D 5687M Guide for Preparation of Flat Composite
Test Method D 6264 may be used as an alternate method of
Panels with Processing Guidelines for Specimen Prepara-
creating damage from an out-of-plane force and measuring
tion
damage resistance properties.
D 6264 Test Method for Measuring the Damage Resistance
1.4 The damage resistance properties generated by this test
of a Fiber-Reinforced Polymer-Matrix Composite to a
method are highly dependent upon several factors, which
Concentrated Quasi-Static Indentation Force
include specimen geometry, layup, impactor geometry, impac-
D 7137/D 7137M Test Method for Compressive Residual
tor mass, impact force, impact energy, and boundary condi-
Strength Properties of Damaged Polymer Matrix Compos-
tions. Thus, results are generally not scalable to other configu-
ite Plates
rations, and are particular to the combination of geometric and
E4 Practices for Force Verification of Testing Machines
physical conditions tested.
E6 Terminology Relating to Methods of Mechanical Test-
1.5 The values stated in either SI units or inch-pound units
ing
are to be regarded separately as standard. Within the text the
E18 Test Methods for Rockwell Hardness and Rockwell
inch-pound units are shown in brackets. The values stated in
Superficial Hardness of Metallic Materials
each system are not exact equivalents; therefore, each system
1 2
This test method is under the jurisdiction of ASTM Committee D30 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Composite Materials and is the direct responsibility of Subcommittee D30.05 on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Structural Test Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved April 1, 2005. Published April 2005. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7136/D7136M–05
E 122 Practice for Calculation of Sample Size to Estimate, to the face of the specimen from the lowest point in the dent to
with a Specified Tolerable Error, the Average of Charac- the plane of the impacted surface that is undisturbed by the
teristic for a Lot or Process dent.
E 177 Practice for Use of the Terms Precision and Bias in 3.2.2 nominal value, n—a value, existing in name only,
ASTM Test Methods
assigned to a measurable property for the purpose of conve-
E 456 Terminology Relating to Quality and Statistics nient designation. Tolerances may be applied to a nominal
E 1309 Guide for Identification of Fiber-Reinforced Poly-
value to define an acceptable range for the property.
mer Matrix Composite Materials in Databases 3.2.3 principal material coordinate system, n—a coordinate
E 1434 GuideforRecordingMechanicalTestDataofFiber-
system with axes that are normal to the planes of symmetry
Reinforced Composite Materials in Databases inherent to a material.
E 1471 Guide for Identification of Fibers, Fillers and Core
3.2.3.1 Discussion—Common usage, at least for Cartesian
Materials in Computerized Material Property Databases
axes (123, xyz, and so forth), generally assigns the coordinate
2.2 Military Standards:
system axes to the normal directions of planes of symmetry in
MIL-HDBK-17-3F Composite Materials Handbook, Vol-
order that the highest property value in a normal direction (for
ume 3—Polymer Matrix Composites Materials Usage,
elastic properties, the axis of greatest stiffness) would be 1 or
Design and Analysis
x, and the lowest (if applicable) would be 3 or z. Anisotropic
MIL-HDBK-728/1 Nondestructive Testing
materials do not have a principal material coordinate system
MIL-HDBK-731A Nondestructive Testing Methods of
duetothetotallackofsymmetry,while,forisotropicmaterials,
Composite Materials—Thermography
any coordinate system is a principal material coordinate
MIL-HDBK-732A Nondestructive Testing Methods of
system. In laminated composites, the principal material coor-
Composite Materials—Acoustic Emission
dinate system has meaning only with respect to an individual
MIL-HDBK-733A Nondestructive Testing Methods of
orthotropic lamina. The related term for laminated composites
Composite Materials—Radiography
is “reference coordinate system.”
-2
MIL-HDBK-787A Nondestructive Testing Methods of
3.2.4 recorded contact force, F [MLT ], n—the force ex-
Composite Materials—Ultrasonics
erted by the impactor on the specimen during the impact event,
NASA Reference Publication 1092 Standard Tests for
as recorded by a force indicator.
Toughened Resin Composites, Revised Edition, July
3.2.5 reference coordinate system, n—a coordinate system
for laminated composites used to define ply orientations. One
of the reference coordinate system axes (normally the Carte-
3. Terminology
sian x-axis) is designated the reference axis, assigned a
position, and the ply principal axis of each ply in the laminate
3.1 Definitions—TerminologyD 3878definestermsrelating
is referenced relative to the reference axis to define the ply
to composite materials. Terminology D 883 defines terms
orientation for that ply.
relating to plastics. TerminologyE6 defines terms relating to
3.2.6 striker tip, n—the portion or component of the impac-
mechanical testing. Terminology E 456 and Practice E 177
torwhichcomesintocontactwiththetestspecimenfirstduring
define terms relating to statistics. In the event of a conflict
the impact event.
between terms, Terminology D 3878 shall have precedence
3.3 Symbols:
over the other standards.
3.2 Definitions of Terms Specific to This Standard—If the A = cross-sectional area of a specimen
term represents a physical quantity, its analytical dimensions C = specified ratio of impact energy to specimen thickness
E
are stated immediately following the term (or letter symbol) in
CV = coefficient of variation statistic of a sample population
fundamental dimension form, using the following ASTM
for a given property (in percent)
standard symbology for fundamental dimensions, shown
D = damage diameter (see Fig. 11)
within square brackets: [M] for mass, [L] for length, [T] for
d = dent depth
time, [u] for thermodynamic temperature, and [nd] for non-
E = potential energy of impactor prior to drop
dimensional quantities. Use of these symbols is restricted to
E = absorbed energy at the time at which force versus time
analytical dimensions when used with square brackets, as the
curve has a discontinuity in force or slope
symbols may have other definitions when used without the
E = energy absorbed by the specimen during the impact
a
brackets.
event
3.2.1 dent depth, d [L], n—residual depth of the depression
E = actual impact energy (incident kinetic energy)
i
formed by an impactor after the impact event. The dent depth
E = absorbed energy at the time of maximum recorded
max
shall be defined as the maximum distance in a direction normal
contact force
F = recorded contact force
F = recorded contact force at which the force versus time
3 curve has a discontinuity in force or slope
Available from U.S. Army Research Laboratory, Materials Directorate, Aber-
deen Proving Ground, MD 21001. F = maximum recorded contact force
max
Available from U.S. Army Materials Technology Laboratory, Watertown, MA
g = acceleration due to gravity
02471.
5 h = specimen thickness
Available from National Aeronautics and Space Administration (NASA)-
Langley Research Center, Hampton, VA 23681-2199. H = impactor drop height
D7136/D7136M–05
NOTE—Clamp tip centered 0.25 in. from edge of cut-out.
FIG. 1 Impact Support Fixture (Inch-Pound Version)
NOTE—Clamp tip centered 6 mm from edge of cut-out.
FIG. 2 Impact Support Fixture (SI Version)
–
l = specimen length
x = mean or average (estimate of mean) of a sample popu-
m = impactor mass
lation for a given property
m = impactor mass for drop height calculation
d
d = impactor displacement
m = impactor mass in standard gravity for drop height
dlbm
calculation
4. Summary of Test Method
n = number of specimens per sample population
4.1 A drop-weight impact test is performed using a bal-
N = number of plies in laminate under test
anced,symmetriclaminatedplate.Damageisimpartedthrough
S = standard deviation statistic of a sample population for
n-1
out-of-plane, concentrated impact (perpendicular to the plane
a given property
of the laminated plate) using a drop weight with a hemispheri-
t = time during impactor drop and impact event
cal striker tip. The damage resistance is quantified in terms of
t = time of initial contact
i
the resulting size and type of damage in the specimen. The
t = contact duration (total duration of the impact event)
T
damage response is a function of the test configuration;
w = specimen width
comparisons cannot be made between materials unless identi-
v = impactor velocity
cal test configurations, test conditions, and so forth are used.
v = impactor velocity at time of initial contact, t
i i
4.2 Optional procedures for recording impact velocity and
W = distance between leading edges of the two flag prongs
applied contact force versus time history data are provided.
on velocity indicator
x = test result for an individual specimen from the sample 4.3 Preferred damage states resulting from the impact are
i
population for a given property located in the center of the plate, sufficiently far from the plate
D7136/D7136M–05
FIG. 3 Representative Rigid Base (Inch-Pound Version)
FIG. 4 Representative Rigid Base (SI Version)
edges such that the local states of stress at the edges and at the 5.2.1 To establish quantitatively the effects of stacking
impact location do not interact during the damage formation sequence, fiber surface treatment, variations in fiber volume
event.
fraction, and processing and environmental variables on the
damage resistance of a particular composite laminate to a
5. Significance and Use
concentrated drop-weight impact force or energy.
5.1 Susceptibilitytodamagefromconcentratedout-of-plane
5.2.2 To compare quantitatively the relative values of the
impact forces is one of the major design concerns of structures
damage resistance parameters for composite materials with
made of advanced composite laminates. Knowledge of the
different constituents. The damage response parameters can
damage resistance properties of a laminated composite plate is
include dent depth, damage dimensions, and through-thickness
useful for product development and material selection.
locations, F , F , E and E , as well as the force versus
1 max 1 max
5.2 Drop-weight impact testing can serve the following
time curve.
purposes:
D7136/D7136M–05
FIG. 5 Impact Device with Cylindrical Tube Impactor Guide Mechanism
FIG. 6 Impact Device with Double Column Impactor Guide Mechanism
5.2.3 To impart damage in a specimen for subsequent capability of composite structures of similar material, thick-
damagetolerancetests,suchasTestMethodD 7137/D 7137M. ness, stacking sequence, and so forth. However, it must be
5.3 The properties obtained using this test method can understood that the damage resistance of a composite structure
provideguidanceinregardtotheanticipateddamageresistance is highly dependent upon several factors including geometry,
D7136/D7136M–05
FIG. 7 Drop-Weight Impact Test Specimen (Inch-Pound Version)
FIG. 8 Drop-Weight Impact Test Specimen (SI Version)
thickness, stiffness, mass, support conditions, and so forth. differences in these parameters. For example, properties ob-
Significant differences in the relationships between impact tained using this test method would more likely reflect the
force/energy and the resultant damage state can result due to damage resistance characteristics of an unstiffened monolithic
D7136/D7136M–05
FIG. 9 Representative Impactor Force versus Time History
FIG. 10 Impactor Force versus Time History with Harmonic Resonance
...
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