1、Designation: D 5379/D 5379M 05Standard Test Method forShear Properties of Composite Materials by the V-NotchedBeam Method1This standard is issued under the fixed designation D 5379/D 5379M; the number immediately following the designation indicates theyear of original adoption or, in the case of rev
2、ision, 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 covers the shear properties of compos-ite materials reinforced by high-modulus fi
3、bers. The compositematerials are limited to continuous-fiber or discontinuous-fiber-reinforced composites in the following material forms:1.1.1 Laminates composed only of unidirectional fibrouslaminae, with the fiber direction oriented either parallel orperpendicular to the loading axis.1.1.2 Lamina
4、tes composed only of woven fabric filamentarylaminae with the warp direction oriented either parallel orperpendicular to the loading axis.1.1.3 Laminates composed only of unidirectional fibrouslaminae, containing equal numbers of plies oriented at 0 and90 in a balanced and symmetric stacking sequenc
5、e, with the 0direction oriented either parallel or perpendicular to the loadingaxis.1.1.4 Short-fiber-reinforced composites with a majority ofthe fibers being randomly distributed.NOTE 1This shear test concept was originally developed withoutreference to fiber direction for use on isotropic material
6、s such as metals orceramics.1.2 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. The values stated ineach system are not exact equivalents; therefore, each systemmust be used independently of
7、 the other. Combining valuesfrom the two systems may result in nonconformance with thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health pr
8、actices 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 Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 2584 Test Method for Ignition Loss of
9、Cured ReinforcedResinsD 2734 Test Method for Void Content of Reinforced Plas-ticsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3878 Terminology for Composite MaterialsD 5229/D 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Com
10、posite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 111 Test Method forYoungs Modulus, Tangent Modulus,and Chord ModulusE 122 Practice for Calculation of Sample Size to Estimate,With a Specified Tolerable Error, the Averag
11、e for Charac-teristic of a Lot or ProcessE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 251 Test Methods for Performance Characteristics ofMetallic Bonded Resistance Strain GagesE 456 Terminology Relating to Quality and StatisticsE 1237 Guide for Installing Bonded Resist
12、ance StrainGages2.2 Other Documents:ANSI Y14.5M-1982 Geometric Dimensioning and Toler-ancing31This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.04 onLamina and Laminate Test Methods.Current edition approved Mar
13、. 1, 2005. Published March 2005. Originallyapproved in 1993. Last previous edition approved in 1998 as D 5379/D 5379M - 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, re
14、fer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ANSI/ASME B 46.1
15、-1985 Surface Texture (Surface Rough-ness, Waviness, and Lay)32.3 ASTM Adjuncts:V-Notched Beam Shear Fixture Machining Drawings43. Terminology3.1 DefinitionsTerminology D 3878 defines terms relatingto high-modulus fibers and their composites. TerminologyD 883 defines terms relating to plastics. Term
16、inology E6defines terms relating to mechanical testing. TerminologyE 456 and Practice E 177 define terms relating to statistics. Inthe event of a conflict between terms, Terminology D 3878shall have precedence over the other standards.3.2 Definitions of Terms Specific to This Standard:NOTE 2If the t
17、erm represents a physical quantity, its analyticaldimensions are stated immediately following the term (or letter symbol) infundamental dimension form, using the following ASTM standard sym-bology for fundamental dimensions, shown within square brackets: Mfor mass, L for length, T for time, Q for th
18、ermodynamic temperature,and nd for nondimensional quantities. Use of these symbols is restrictedto analytical dimensions when used with square brackets, as the symbolsmay have other definitions when used without the brackets.3.2.1 in-plane shear, nany of the shear properties describ-ing the response
19、 resulting from a shear load or deformationapplied to the 1-2 material plane. (See also material coordinatesystem.)3.2.2 interlaminar shear, nany of the shear propertiesdescribing the response resulting from a shear load or defor-mation applied to the 1-3 or 2-3 material planes. (See alsomaterial co
20、ordinate system.)3.2.3 material coordinate system, na Cartesian coordinatesystem describing the principal material coordinate system,using 1, 2, and 3 for the axes, as shown in Fig. 1.3.2.4 nominal value, na value, existing in name only,assigned to a measurable property for the purpose of conve-nien
21、t designation. Tolerances may be applied to a nominalvalue to define an acceptable range for the property.3.2.5 shear strength, nthe shear stress carried by a mate-rial at failure under a pure shear condition.3.2.5.1 DiscussionThere are no standard test methods thatare capable of producing a perfect
22、ly pure shear stress conditionto failure for every material, although some test methods cancome acceptably close for a specific material for a givenengineering purpose.3.3 Symbols:3.3.1 Aminimum cross-sectional area of a coupon.3.3.2 CVcoefficient of variation statistic of a samplepopulation for a g
23、iven property (in percent).3.3.3 Fsuultimate shear strength in the test direction.3.3.4 Fuultimate strength in the test direction.3.3.5 F (offset)the value of the shear stress at theintersection of the shear chord modulus of elasticity and thestress strain curve when the modulus is offset along the
24、shearstrain axis from the origin by the reported strain offset value.3.3.6 Gshear modulus of elasticity in the test direction.3.3.7 hcoupon thickness.3.3.8 nnumber of coupons per sample population.3.3.9 Pload carried by test coupon.3.3.10 Pf load carried by test coupon at failure.3.3.11 Pmax maximum
25、 load carried by test coupon beforefailure.3.3.12 sn1standard deviation statistic of a sample popu-lation for a given property.3.3.13 wcoupon width.3.3.14 xitest result for an individual coupon from thesample population for a given property.3.3.15 xmean or average (estimate of mean) of a samplepopul
26、ation for a given property.3.3.16 gshear strain.3.3.17 egeneral symbol for strain, whether normal strainor shear strain.3.3.18 eindicated normal strain from strain transducer orextensometer.3.3.19 snormal stress.3.3.20 tshear stress.3.3.21 uply orientation angle.4. Summary of Test Method4.1 A materi
27、al coupon in the form of a rectangular flat stripwith symmetrical centrally located v-notches, shown schemati-cally in Fig. 2, is loaded in a mechanical testing machine by aspecial fixture (shown schematically in Fig. 3 and in moredetail in the machining drawings of ASTM AdjunctADJD5379).54.2 The sp
28、ecimen is inserted into the fixture with the notchlocated along the line of action of loading by means of analignment tool that references the fixture. The two halves of thefixture are compressed by a testing machine while monitoringload. The relative displacement between the two fixture halvesloads
29、 the notched specimen. By placing two strain gage4Available from ASTM International Headquarters. Order Adjunct No.ADJD5379.5The specimen and fixture are based upon work at the University of WyomingComposite Materials Research Group (1, 2), and were subsequently modified by thegroup (3, 4) into the
30、configuration used by this test method. The Wyominginvestigations referred to the earlier work of Arcan (5-7) and Iosipescu (8-10), andthe later work of a number of other researchers, including Refs (11-16) (earlyhistorical perspectives are given in Refs (1, 17). The boldface numbers inparentheses r
31、efer to the list of references at the end of this standard.FIG. 1 Material Coordinate SystemD 5379/D 5379M 052elements, oriented at 645 to the loading axis, in the middle ofthe specimen (away from the notches) and along the loadingaxis, the shear response of the material can be measured.4.3 The load
32、ing can be idealized as asymmetric flexure, asshown by the shear and bending moment diagrams of Fig. 4.6The notches influence the shear strain along the loadingdirection, making the distribution more uniform than would beseen without the notches. While the degree of uniformity is afunction of materi
33、al orthotropy, the best overall results, whentesting in the 1-2 plane, have been obtained on 0/90ns-typelaminates.5. Significance and Use5.1 This test method is designed to produce shear propertydata for material specifications, research and development,quality assurance, and structural design and a
34、nalysis. Eitherin-plane or interlaminar shear properties may be evaluated,depending upon the orientation of the material coordinatesystem relative to the loading axis. Factors that influence theshear response and should therefore be reported include thefollowing: material, methods of material prepar
35、ation and lay-up, specimen stacking sequence, specimen preparation, speci-men conditioning, environment of testing, specimen alignmentand gripping, speed of testing, time at temperature, voidcontent, and volume percent reinforcement.5.2 In anisotropic materials, properties may be obtained inany of t
36、he six possible shear planes by orienting the testingplane of the specimen with the desired material plane (1-2 or6While the idealization indicates constant shear loading and zero bendingmoment in the specimen at the notches, the actual load application is distributed andimperfect, which contributes
37、 to asymmetry in the shear strain distribution and to acomponent of normal stress that is particularly deleterious to 90n specimens (16).Nominal Specimen Dimensionsd1= 20.0 mm 0.75 in.d2= 4.0 mm 0.15 in.h = as requiredL = 76.0 mm 3.0 in.r = 1.3 mm 0.05 in.w = 12.0 mm 0.45 in.FIG. 2 V-Notched Beam Te
38、st Coupon SchematicFIG. 3 V-Notched Beam Test Fixture SchematicNOTEThe value of the dimension b is not critical to the concept.FIG. 4 Idealized Force, Shear, and Moment DiagramsD 5379/D 5379M 0532-1, 1-3 or 3-1, 2-3 or 3-2). Only a single shear plane may beevaluated for any given specimen. Propertie
39、s, in the testdirection, which may be obtained from this test method,include the following:5.2.1 Shear stress/strain response,5.2.2 Ultimate strength,5.2.3 Ultimate strain,5.2.4 Shear chord modulus of elasticity, and5.2.5 Transition strain.6. Interferences6.1 Material and Specimen PreparationPoor ma
40、terialfabrication practices, lack of control of fiber alignment, anddamage induced by improper coupon machining are knowncauses of high material data scatter in composites.6.2 Materials and Coarse StructureOne of the fundamen-tal assumptions of this test method is that the material must berelatively
41、 homogeneous with respect to the size of the testsection. Materials that have relatively coarse features withrespect to the test section dimensions, such as fabrics usinglarge filament count tows (such as tows of 12 000 filaments ormore) or certain braided structures, should not be tested withthis s
42、pecimen size. Scale-up of the specimen and the fixturingto accommodate such materials is possible, but is beyond thescope of this test method.6.3 Elastic Modulus MeasurementThe calculations in thistest method assume a uniform shear stress state between thenotches. The actual degree of uniformity var
43、ies with the levelof material orthotropy and the direction of loading. Bothanalysis and full-field experimental strain measurement haveshown that when testing in the 1-2 plane, 0n specimens resultin an elastic modulus estimate that is too high (about 10 % toohigh for carbon/epoxy), while 90n specime
44、ns of the samematerial result in a value that is about 20 % too low. The mostaccurate measurements of in-plane shear modulus for unidi-rectional materials have been shown to result from the 0/90nsspecimen.6.4 Load EccentricityTwisting of the specimen duringloading can occur, affecting strength resul
45、ts, and especially,elastic modulus measurement. Twisting may occur due to anout-of-tolerance fixture, or from specimens that are too thin(unstable), improperly installed in the fixture, out-of-tolerancebecause of poor specimen preparation, or of a material con-figuration with an extremely low tolera
46、nce to twist. It isrecommended that at least one specimen of each sample betested with back-to-back rosettes to evaluate the degree oftwist. Evaluate the percent twist for the specimen by substitut-ing the shear modulus from each side, Gaand Gb, into |(Ga Gb)/(Ga+ Gb)| 3 100, evaluated at 0.004 abso
47、lute strain.If the amount of twist is greater than 3 %, then the specimensshould be examined for cause of the twisting, and corrected, ifpossible. If no cause is apparent or correction possible, and thetwisting persists, then the shear modulus measurement shouldbe made using the average response of
48、back-to-back rosettes.NOTE 3Twisting as a result of minor tolerance variations can bemitigated by use of a thin compliant interface, such as a plastic-backedadhesive tape, between the fixture and the load-bearing surface of thespecimen.6.5 Specimen Geometry ModificationsDetailed stressanalysis of th
49、e v-notch specimen has shown that adjustments tothe notch dimensions (notch angle, depth, and radius) canminimize non-uniformity in the shear-stress distribution as aresult of material orthotropy. Recommendations for notchdimensions versus degree of material orthotropy are still beingdeveloped. In the interim, and in order to minimize thecomplexity of this test method, a single standard geometry hasbeen adopted. However, variations to the notch angle, depth,and radius for the purpose of optimizing the specim
