ImageVerifierCode 换一换
格式:PDF , 页数:5 ,大小:133.22KB ,
资源ID:526561      下载积分:5000 积分
快捷下载
登录下载
邮箱/手机:
温馨提示:
如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
如填写123,账号就是123,密码也是123。
特别说明:
请自助下载,系统不会自动发送文件的哦; 如果您已付费,想二次下载,请登录后访问:我的下载记录
支付方式: 支付宝扫码支付 微信扫码支付   
注意:如需开发票,请勿充值!
验证码:   换一换

加入VIP,免费下载
 

温馨提示:由于个人手机设置不同,如果发现不能下载,请复制以下地址【http://www.mydoc123.com/d-526561.html】到电脑端继续下载(重复下载不扣费)。

已注册用户请登录:
账号:
密码:
验证码:   换一换
  忘记密码?
三方登录: 微信登录  

下载须知

1: 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。
2: 试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。
3: 文件的所有权益归上传用户所有。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 本站仅提供交流平台,并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

版权提示 | 免责声明

本文(ASTM D7956 D7956M-2014 2740 Standard Practice for Compressive Testing of Thin Damaged Laminates Using a Sandwich Long Beam Fixture Specimen《使用夹心长梁夹具试样对薄损坏层压板进行抗压试验的标准实施规程》.pdf)为本站会员(rimleave225)主动上传,麦多课文库仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文库(发送邮件至master@mydoc123.com或直接QQ联系客服),我们立即给予删除!

ASTM D7956 D7956M-2014 2740 Standard Practice for Compressive Testing of Thin Damaged Laminates Using a Sandwich Long Beam Fixture Specimen《使用夹心长梁夹具试样对薄损坏层压板进行抗压试验的标准实施规程》.pdf

1、Designation: D7956/D7956M 14Standard Practice forCompressive Testing of Thin Damaged Laminates Using aSandwich Long Beam Fixture Specimen1This standard is issued under the fixed designation D7956/D7956M; the number immediately following the designation indicates theyear of original adoption or, in t

2、he case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers an approach for compressive test-ing thin damaged multidirection

3、al polymer matrix compositelaminates reinforced by high-modulus fibers using a sandwichlong beam flexure specimen. It provides a test configuration inwhich the core does not constrain any protruding back sidedamage. It is limited to testing of monolithic solid laminateswhich are too thin to be teste

4、d using typical anti-bucklingfixtures. It does not cover compressive testing of damagedsandwich panel facings. The composite material forms arelimited to continuous-fiber or discontinuous-fiber (tape orfabric, or both) reinforced composites in which the laminate isbalanced and symmetric with respect

5、 to the test direction1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result i

6、n non-conformancewith the standard.1.2.1 Within the text the inch-pound units are shown inbrackets.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 healt

7、h practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C274 Terminology of Structural Sandwich ConstructionsD883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD3410 Test Method for Compressive Properti

8、es of PolymerMatrix Composite Materials with Unsupported Gage Sec-tion by Shear LoadingD6264/D6264M Test Method for Measuring the DamageResistance of a Fiber-Reinforced Polymer-Matrix Com-posite to a Concentrated Quasi-Static Indentation ForceD7136/D7136M Test Method for Measuring the DamageResistan

9、ce of a Fiber-Reinforced Polymer Matrix Com-posite to a Drop-Weight Impact EventD7137/D7137M Test Method for Compressive ResidualStrength Properties of Damaged Polymer Matrix Compos-ite PlatesD7249/D7249M Test Method for Facing Properties of Sand-wich Constructions by Long Beam FlexureE6 Terminology

10、 Relating to Methods of Mechanical TestingE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE13

11、09 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases3. Terminology3.1 DefinitionsTerminology D3878 defines terms relatingto high-modulus fibers and their compo

12、sites. TerminologyC274 defines terms relating to structural sandwich construc-tions. Terminology D883 defines terms relating to plastics.Terminology E6 defines terms relating to mechanical testing.Terminology E456 and Practice E177 define terms relating tostatistics. In the event of a conflict betwe

13、en terms, TerminologyD3878 shall have precedence over the other terminologies.4. Summary of Practice4.1 This practice consists of fabricating a compositelaminate, damaging the laminate using either Test MethodD6264/D6264M or Test Method D7136/D7136M, bonding theimpacted or indented side of the lamin

14、ate onto core and a backside facing to form a sandwich panel, and testing the damagedlaminate in compression using Test Method D7249/D7249M.1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.09 onSandwich Const

15、ruction.Current edition approved Aug. 1, 2014. Published September 2014. DOI:10.1520/D7956_D7956M-14.2For 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 D

16、ocument Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 This practice provides a standard method of testingdamaged composite laminates which are too thin to be testedusing typ

17、ical anti-buckling fixtures, such as those used in TestMethod D7137/D7137M. The laminate is first impacted orindented in order to produce a damage state representative ofactual monolithic solid laminate structure. Impacting or staticindentation is not performed on an assembled sandwich panel,as the

18、damage state is altered by energy absorption in the coreand by support of the core during the impact or indentationevent. After damaging, the laminate is bonded onto the corewith the impacted or indentation side of the laminate againstthe core, and with a localized un-bonded area encompassingthe dam

19、age site. Fig. 1 illustrates the adhesive removal to avoidthe damaged area and the assembly of the sandwich specimenwith the impacted damaged laminate flipped over from theimpacting or indentation orientation. The final assembledsandwich specimen is then tested using a long beam flexuresetup with th

20、e damaged laminate being on the compressionside. The sandwich panel configuration is used as a form ofanti-buckling support for the thin damaged laminate.5.2 Susceptibility to damage from concentrated out-of-planeforces is one of the major design concerns of many structuresmade of advanced composite

21、 laminates. Knowledge of thedamage resistance and damage tolerance properties of alaminated composite plate is useful for product developmentand material selection.5.3 The residual strength data obtained using this testmethod is used in research and development activities as wellas for design allowa

22、bles; however the results are specific to thegeometry and physical conditions tested and are generally notscalable to other configurations.5.4 The properties obtained using this test method canprovide guidance in regard to the anticipated damage tolerancecapability of composite structures of similar

23、 material,thickness, stacking sequence, and so forth. However, it must beunderstood that the damage tolerance of a composite structureis highly dependent upon several factors including geometry,stiffness, support conditions, and so forth. Significant differ-ences in the relationships between the exi

24、stent damage stateand the residual compressive strength can result due todifferences in these parameters. For example, residual strengthand stiffness properties obtained using this test method wouldmore likely reflect the damage tolerance characteristics of anun-stiffened monolithic skin or web than

25、 that of a skin attachedto substructure which resists out-of-plane deformation.5.5 The reporting section requires items that tend to influ-ence residual compressive strength to be reported; theseinclude the following: material, methods of materialfabrication, accuracy of lay-up orientation, laminate

26、 stackingsequence and overall thickness, specimen geometry, specimenpreparation, specimen conditioning, environment of testing,void content, volume percent reinforcement, type, size andFIG. 1 Sandwich Specimen AssemblyD7956/D7956M 142location of damage (including method of non-destructiveinspection

27、(NDI), fixture geometry, time at temperature, andspeed of testing.5.6 Properties that result from the residual strength assess-ment include the following: compressive residual strengthFCAI.6. Interferences6.1 The response of a damaged specimen is dependent uponmany factors, such as laminate thicknes

28、s, ply thickness, stack-ing sequence, environment, damage type, damage geometry,damage location, and loading/support conditions.Consequently, comparisons cannot be made between materialsunless identical test configurations, test conditions, and lami-nate configurations are used. Therefore, all detai

29、ls of the testconfiguration shall be reported in the results. Specific structuralconfigurations and boundary conditions must be consideredwhen applying the data generated using this test method todesign applications.6.2 Material OrthotropyThe degree of laminate orthot-ropy strongly affects the failu

30、re mode and measured compres-sive residual strength.6.3 Thickness ScalingThick composite structures do notnecessarily fail at the same strengths as thin structures with thesame laminate orientation (that is, strength does not alwaysscale linearly with thickness). Further, the damage state for agiven

31、 level of impact or indentation energy or measuredsurface dent depth varies with laminate thickness. Thus, datagathered using this test method may not translate directly intoequivalent thick-structure properties.6.4 Damage Geometry and LocationThe size, shape, andlocation of damage (both within the

32、plane of the plate andthrough-the-thickness) can significantly affect the deformationand strength behavior of the specimen. Edge effects, boundaryconstraints, and the damaged stress/strain field can interact ifthe damage size becomes too large relative to the length andwidth dimensions of the specim

33、en.6.5 EnvironmentResults are affected by the environmentalconditions under which specimens are conditioned, as well asthe conditions under which the tests are conducted. Specimenstested in various environments can exhibit significant differ-ences in stiffness. Critical environments must be assessed

34、independently for each specific combination of core material,facing material, and core-to-facing interfacial adhesive (ifused) that is tested.6.6 Core MaterialIf the core material has insufficientshear or compressive strength, it is possible that the core maylocally crush at or near the loading poin

35、ts thereby resulting infacesheet failure due to local stresses. In other cases, facingfailure can cause local core crushing. When there is both facingand core failure in the vicinity of one of the loading points, itcan be difficult to determine the failure sequence in a post-mortem inspection of the

36、 specimen as the failed specimenslook very similar for both sequences.6.7 DamagingRefer to Test Methods D6264/D6264M orD7136/D7136M for indentation or impact related interfer-ences.7. Sampling and Test Specimens7.1 SamplingTest at least five specimens per test condi-tion unless valid results can be

37、gained through the use of fewerspecimens, as in the case of a designed experiment. Forstatistically significant data, consult the procedures outlined inPractice E122. Report the method of sampling.7.2 Specimen and Fixture GeometryThe test requestorshall specify all specimen dimensions and materials

38、along withthe loading fixture dimensions. Refer to Test Method D7249/D7249M for sandwich beam specimen sizing requirements andguidelines.7.2.1 SpecimenThe test specimens shall be rectangular incross section. The width of the specimen shall be at least three(3) times the width of the damage (as deter

39、mined by NDI).NOTE 1The recommended specimen width is five (5) times thedamage width, however this may not be practical in all cases. Also, it maynot be possible to accurately predict the damage sizes prior to fabricationof the test specimens. As impact or indentation damage diameters areoften on th

40、e order of 25 mm 1.0 inch, a typical specimen width is127 mm 5.0 inch. Specimen width should be minimized to avoidexcessive anti-clastic bending.7.2.2 Loading FixtureThe loading span should be in-creased from the Test Method D7249/D7249M standard speci-men dimension of 100 mm 4.0 in to the minimum o

41、f adimension equal to the specimen width or three (3) times thedimension of the damage measured in the axial direction of thespecimen. The support span may have to be modified from theTest Method D7249/D7249M standard specimen dimension inorder for the specimen to produce the desired facesheet failu

42、remode.7.3 Back Side FacingsThe back side facings may use thesame laminate as the laminate to be tested in compression, ormay use a similar laminate. The back side facing should haveequal or greater stiffness (Et) than the top (compressive) facingand shall have greater tensile strength than the anti

43、cipatedcompressive strength of the damaged laminate to be tested. Theback side facing should have a similar coefficient of thermalexpansion as the top facing to avoid panel warpage duringfabrication.NOTE 2Metallic sheets are not recommended for the back facings asit can be difficult to machine a san

44、dwich panel with dissimilar materialsfor the two facings.7.4 CoreThe core material for the sandwich panels shallhave sufficient shear and compression strength to avoid failuresin the core prior to facing failure. Refer to Test MethodD7249/D7249M for core material selection guidelines7.5 AdhesiveThe

45、adhesive material for bonding the fac-ings to the core of the sandwich panel shall have sufficientshear strength at the test temperature to avoid failure in thebond prior to facing failure. The adhesive used to bond thedamaged facing shall not significantly flow into the cutout areaaround the damage

46、 location.8. Procedure8.1 Fabricate Laminate and Back Side FacingsFabricatethe laminates to be tested. Also fabricate back (tension) sidefacings for the sandwich specimens.D7956/D7956M 143NOTE 3It is acceptable to fabricate larger panels with sufficientmaterial for several specimens. Mark the locati

47、on of each specimen,damage the large panel once in the center of each specimen, bond thelaminate onto the core and back facing, then machine each individualsandwich specimen.8.2 Perform DamagingImpact damage using either TestMethod D6264/D6264M or Test Method D7136/D7136M,using an impact energy or i

48、ndentation depth to be supplied bythe test requestor. Apply a single impact or indentation in thecenter of each specimen to be tested. Record the damagemeasurements per Test Method D6264/D6264M or TestMethod D7136/D7136M.8.3 Fabricate Sandwich SpecimensFabricate the sand-wich panels using the damage

49、d laminates, the back sidefacings, and the selected core and adhesive. The damagedlaminates shall be bonded to the core with the side of thelaminate which was impacted or indented being bonded to thecore (flipped upside down from the orientation during impact-ing or indention); see Fig. 1. The adhesive used to bond thedamaged laminate shall have a circular area without adhesive,centered over the damage site, with a diameter larger than thegeneral disbond area detected by NDI. A typical size for thecutout in the adhesive is 51 mm 2.0 inch (it is acceptabl

copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
备案/许可证编号:苏ICP备17064731号-1