1、Designation: D 7136/D 7136M 07Standard Test Method forMeasuring the Damage Resistance of a Fiber-ReinforcedPolymer Matrix Composite to a Drop-Weight Impact Event1This standard is issued under the fixed designation D 7136/D 7136M; the number immediately following the designation indicates theyear of
2、original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method determines the damage resistance ofmultid
3、irectional polymer matrix composite laminated platessubjected to a drop-weight impact event. The compositematerial forms are limited to continuous-fiber reinforced poly-mer matrix composites, with the range of acceptable testlaminates and thicknesses defined in 8.2.1.2 A flat, rectangular composite
4、plate is subjected to anout-of-plane, concentrated impact using a drop-weight devicewith a hemispherical impactor. The potential energy of thedrop-weight, as defined by the mass and drop height of theimpactor, is specified prior to test. Equipment and proceduresare provided for optional measurement
5、of contact force andvelocity during the impact event. The damage resistance isquantified in terms of the resulting size and type of damage inthe specimen.1.3 The test method may be used to screen materials fordamage resistance, or to inflict damage into a specimen forsubsequent damage tolerance test
6、ing. When the impacted plateis tested in accordance with Test Method D 7137/D 7137M, theoverall test sequence is commonly referred to as the Compres-sion After Impact (CAI) method. Quasi-static indentation perTest Method D 6264 may be used as an alternate method ofcreating damage from an out-of-plan
7、e force and measuringdamage resistance properties.1.4 The damage resistance properties generated by this testmethod are highly dependent upon several factors, whichinclude specimen geometry, layup, impactor geometry, impac-tor mass, impact force, impact energy, and boundary condi-tions. Thus, result
8、s are generally not scalable to other configu-rations, and are particular to the combination of geometric andphysical conditions tested.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. Within the text theinch-pound units are shown in brackets. Th
9、e values stated ineach system are not exact equivalents; therefore, each systemmust be used independently of the other. Combining valuesfrom the two systems may result in nonconformance with thestandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with
10、its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 792 Test Methods for Density and Specific Gravity (Rela-tive Densit
11、y) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3763 Test Method for High Speed Puncture Properties ofPlastics using Load and Displacement SensorsD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Metho
12、d for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite LaminatesD 5687/D 5687M Guide for Preparation of Flat CompositePanels with Processing Guidelines for Specimen Prepara-tionD 6264 Test Method for Measuring the Damage Resistanceof a Fiber-Reinforced Polymer-
13、Matrix Composite to aConcentrated Quasi-Static Indentation ForceD 7137/D 7137M Test Method for Compressive ResidualStrength Properties of Damaged Polymer Matrix Compos-ite PlatesE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE18 Test M
14、ethods for Rockwell Hardness and Rockwell1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.05 onStructural Test Methods.Current edition approved Oct. 1, 2007. Published November 2007. Originallyapproved in 200
15、5. Last previous edition approved in 2005 as D 7136/D 7136M -05e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM web
16、site.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Superficial Hardness of Metallic MaterialsE 122 Practice for Calculation of Sample Size to Estimate,with a Specified Tolerable Error, the Average of Charac-teristic for a Lot or Pr
17、ocessE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 456 Terminology Relating to Quality and StatisticsE 1309 Guide for Identification of Fiber-Reinforced Poly-mer Matrix Composite Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced C
18、omposite Materials in Databases2.2 Military Standards:MIL-HDBK-17-3F Composite Materials Handbook, Vol-ume 3Polymer Matrix Composites Materials Usage,Design and Analysis3MIL-HDBK-728/1 Nondestructive Testing4MIL-HDBK-731A Nondestructive Testing Methods ofComposite MaterialsThermography4MIL-HDBK-732A
19、 Nondestructive Testing Methods ofComposite MaterialsAcoustic Emission4MIL-HDBK-733A Nondestructive Testing Methods ofComposite MaterialsRadiography4MIL-HDBK-787A Nondestructive Testing Methods ofComposite MaterialsUltrasonics4NASA Reference Publication 1092 Standard Tests forToughened Resin Composi
20、tes, Revised Edition, July198353. Terminology3.1 DefinitionsTerminology D 3878 defines terms relatingto composite materials. Terminology D 883 defines termsrelating to plastics. Terminology E6defines terms relating tomechanical testing. Terminology E 456 and Practice E 177define terms relating to st
21、atistics. In the event of a conflictbetween terms, Terminology D 3878 shall have precedenceover the other standards.3.2 Definitions of Terms Specific to This StandardIf theterm represents a physical quantity, its analytical dimensionsare stated immediately following the term (or letter symbol) infun
22、damental dimension form, using the following ASTMstandard symbology for fundamental dimensions, shownwithin square brackets: M for mass, L for length, T fortime, u for thermodynamic temperature, and nd for non-dimensional quantities. Use of these symbols is restricted toanalytical dimensions when us
23、ed with square brackets, as thesymbols may have other definitions when used without thebrackets.3.2.1 dent depth, d L, nresidual depth of the depressionformed by an impactor after the impact event. The dent depthshall be defined as the maximum distance in a direction normalto the face of the specime
24、n from the lowest point in the dent tothe plane of the impacted surface that is undisturbed by thedent.3.2.2 nominal value, na value, existing in name only,assigned to a measurable property for the purpose of conve-nient designation. Tolerances may be applied to a nominalvalue to define an acceptabl
25、e range for the property.3.2.3 principal material coordinate system, na coordinatesystem with axes that are normal to the planes of symmetryinherent to a material.3.2.3.1 DiscussionCommon usage, at least for Cartesianaxes (123, xyz, and so forth), generally assigns the coordinatesystem axes to the n
26、ormal directions of planes of symmetry inorder that the highest property value in a normal direction (forelastic properties, the axis of greatest stiffness) would be 1 orx, and the lowest (if applicable) would be 3 or z. Anisotropicmaterials do not have a principal material coordinate systemdue to t
27、he total lack of symmetry, while, for isotropic materials,any coordinate system is a principal material coordinatesystem. In laminated composites, the principal material coor-dinate system has meaning only with respect to an individualorthotropic lamina. The related term for laminated compositesis “
28、reference coordinate system.”3.2.4 recorded contact force, F MLT-2, nthe force ex-erted by the impactor on the specimen during the impact event,as recorded by a force indicator.3.2.5 reference coordinate system, na coordinate systemfor laminated composites used to define ply orientations. Oneof the
29、reference coordinate system axes (normally the Carte-sian x-axis) is designated the reference axis, assigned aposition, and the ply principal axis of each ply in the laminateis referenced relative to the reference axis to define the plyorientation for that ply.3.2.6 striker tip, nthe portion or comp
30、onent of the impac-tor which comes into contact with the test specimen first duringthe impact event.3.3 Symbols:A = cross-sectional area of a specimenCE= specified ratio of impact energy to specimen thicknessCV = coefficient of variation statistic of a sample populationfor a given property (in perce
31、nt)D = damage diameter (see Fig. 11)d = dent depthE = potential energy of impactor prior to dropE1= absorbed energy at the time at which force versus timecurve has a discontinuity in force or slopeEa= energy absorbed by the specimen during the impacteventEi= actual impact energy (incident kinetic en
32、ergy)Emax= absorbed energy at the time of maximum recordedcontact forceF = recorded contact forceF1= recorded contact force at which the force versus timecurve has a discontinuity in force or slopeFmax= maximum recorded contact forceg = acceleration due to gravityh = specimen thicknessH = impactor d
33、rop height3Available from U.S. Army Research Laboratory, Materials Directorate, Aber-deen Proving Ground, MD 21001.4Available from U.S. Army Materials Technology Laboratory, Watertown, MA02471.5Available from National Aeronautics and Space Administration (NASA)-Langley Research Center, Hampton, VA 2
34、3681-2199.D 7136/D 7136M 072l = specimen lengthm = impactor massmd= impactor mass for drop height calculationmdlbm= impactor mass in standard gravity for drop heightcalculationn = number of specimens per sample populationN = number of plies in laminate under testSn-1= standard deviation statistic of
35、 a sample population fora given propertyt = time during impactor drop and impact eventti= time of initial contacttT= contact duration (total duration of the impact event)w = specimen widthv = impactor velocityvi= impactor velocity at time of initial contact, tiW12= distance between leading edges of
36、the two flag prongson velocity indicatorxi= test result for an individual specimen from the samplepopulation for a given propertyx= mean or average (estimate of mean) of a sample popu-lation for a given propertyd = impactor displacement4. Summary of Test Method4.1 A drop-weight impact test is perfor
37、med using a bal-anced, symmetric laminated plate. Damage is imparted throughout-of-plane, concentrated impact (perpendicular to the planeof the laminated plate) using a drop weight with a hemispheri-cal striker tip. The damage resistance is quantified in terms ofthe resulting size and type of damage
38、 in the specimen. Thedamage response is a function of the test configuration;comparisons cannot be made between materials unless identi-cal test configurations, test conditions, and so forth are used.4.2 Optional procedures for recording impact velocity andapplied contact force versus time history d
39、ata are provided.4.3 Preferred damage states resulting from the impact arelocated in the center of the plate, sufficiently far from the plateNOTEClamp tip centered 0.25 in. from edge of cut-out.FIG. 1 Impact Support Fixture (Inch-Pound Version)NOTEClamp tip centered 6 mm from edge of cut-out.FIG. 2
40、Impact Support Fixture (SI Version)D 7136/D 7136M 073edges such that the local states of stress at the edges and at theimpact location do not interact during the damage formationevent.5. Significance and Use5.1 Susceptibility to damage from concentrated out-of-planeimpact forces is one of the major
41、design concerns of manystructures made of advanced composite laminates. Knowledgeof the damage resistance properties of a laminated compositeplate is useful for product development and material selection.5.2 Drop-weight impact testing can serve the followingpurposes:5.2.1 To establish quantitatively
42、 the effects of stackingsequence, fiber surface treatment, variations in fiber volumefraction, and processing and environmental variables on thedamage resistance of a particular composite laminate to aconcentrated drop-weight impact force or energy.5.2.2 To compare quantitatively the relative values
43、 of thedamage resistance parameters for composite materials withdifferent constituents. The damage response parameters caninclude dent depth, damage dimensions, and through-thicknesslocations, F1, Fmax, E1and Emax, as well as the force versustime curve.FIG. 3 Representative Rigid Base (Inch-Pound Ve
44、rsion)FIG. 4 Representative Rigid Base (SI Version)D 7136/D 7136M 0745.2.3 To impart damage in a specimen for subsequentdamage tolerance tests, such as Test Method D 7137/D 7137M.5.3 The properties obtained using this test method canprovide guidance in regard to the anticipated damage resistancecapa
45、bility of composite structures of similar material, thick-ness, stacking sequence, and so forth. However, it must beunderstood that the damage resistance of a composite structureis highly dependent upon several factors including geometry,FIG. 5 Impact Device with Cylindrical Tube Impactor Guide Mech
46、anismFIG. 6 Impact Device with Double Column Impactor Guide MechanismD 7136/D 7136M 075thickness, stiffness, mass, support conditions, and so forth.Significant differences in the relationships between impactforce/energy and the resultant damage state can result due todifferences in these parameters.
47、 For example, properties ob-tained using this test method would more likely reflect thedamage resistance characteristics of an unstiffened monolithicFIG. 7 Drop-Weight Impact Test Specimen (Inch-Pound Version)FIG. 8 Drop-Weight Impact Test Specimen (SI Version)D 7136/D 7136M 076skin or web than that
48、 of a skin attached to substructure whichresists out-of-plane deformation. Similarly, test specimen prop-erties would be expected to be similar to those of a panel withequivalent length and width dimensions, in comparison tothose of a panel significantly larger than the test specimen,which tends to
49、divert a greater proportion of the impact energyinto elastic deformation.5.4 The standard impactor geometry has a blunt, hemi-spherical striker tip. Historically, for the standard laminateconfiguration and impact energy, this impactor geometry hasFIG. 9 Representative Impactor Force versus Time HistoryFIG. 10 Impactor Force versus Time History with Harmonic ResonanceD 7136/D 7136M 077generated a larger amount of internal damage for a givenamount of external damage, when compared with that observedfor similar impacts using sharp striker tips.5.5
