1、Designation: C 394 00 (Reapproved 2008)Standard Test Method forShear Fatigue of Sandwich Core Materials1This standard is issued under the fixed designation C 394; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the effect ofrepeated shear loads on sandwich core materials.1.2 The values stated i
3、n SI units are to be regarded as thestandard. The inch-pound units given may be approximate.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 pract
4、ices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 273 Test Method for Shear Properties of Sandwich CoreMaterialsE4 Practices for Force Verification of Testing Machines3. Significance and Use3.1 Usually the most critical stress t
5、o which a sandwichpanel core is subjected is shear. The effect of repeated shearstresses on the core material can be very important.3.2 These test methods provide a standard method ofobtaining the sandwich core shear fatigue properties.4. Apparatus4.1 Fatigue Testing Machine, any standard constant l
6、oadfatigue testing machine capable of applying a direct stress tothe specimen and equipped with a counter. The load measuringsystem used shall have an accuracy of 61 % of the indicatedvalue. The accuracy of the test machine shall be verified inaccordance with Practices E4.4.2 Testing Machine, any st
7、andard universal testing machinecapable of operation at a constant rate of motion of thecross-head. The load measuring system used shall have anaccuracy of 61 % of the indicated value. The accuracy of thetest machine shall be verified in accordance with Practices E4.4.3 Test Fixtures, test fixtures
8、similar to those described inTest Method C 273.4.4 Micrometer, Gage, or Caliper, capable of measuringaccurately to 0.025 mm (0.001 in.).5. Test Specimens5.1 The test specimens shall be similar to those described inTest Method C 273, except that the core material shall bebonded directly to the fixtur
9、e plates. The dimensions of thespecimen shall be such that the line of load action passesthrough the diagonally opposite corners of the core material.5.2 The number of test specimens and the method of theirselection depend on the purpose of the particular test underconsideration. It is recommended t
10、hat at least five specimensare used for static control tests, and three specimens for eachstress level to be tested. For establishment of an S-N curve ofstress versus number of cycles to failure, test at least threestress levels.6. Conditioning6.1 When the physical properties of the component materi
11、-als are affected by moisture, bring the test specimens toconstant weight (61 %) before testing, preferably in a condi-tioning room having temperature and humidity control. Con-duct the tests under the same temperature and humidityconditions. A temperature of 23 6 3C (73 6 5F) and arelative humidity
12、 of 50 6 5 % are recommended as standardconditions.7. Procedure7.1 The length and width dimensions of the specimen shallbe measured to the nearest 0.25 mm (0.01 in.) and the thicknessdimension to the nearest 0.025 mm (0.001 in.). Weight thespecimen to the nearest 0.1 g and calculate the specimendens
13、ity.7.2 Before the fatigue tests, test a minimum of five controlspecimens statically in a standard test machine in accordancewith Test Method C 273. Use the average of the five specimensas the 100 % level for the fatigue tests.1This test method is under the jurisdiction of ASTM Committee D30 onCompo
14、site Materials and is the direct responsibility of Subcommittee D30.09 onSandwich Construction.Current edition approved March 1, 2008. Published April 2008. Originallyapproved in 1957. Last previous edition approved in 2000 as C 394 00 .2For referenced ASTM standards, visit the ASTM website, www.ast
15、m.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.3 The s
16、tress levels to be tested shall be agreed upon by thepurchaser and the seller, or other parties involved. The stresslevel is defined as the maximum repeated stress to which thespecimen is subjected.7.4 For standard tests, use a stress ratio of minimum tomaximum load of 0.10, unless agreed upon previ
17、ously by theparties involved. Apply the mean load (50 % of differencebetween maximum and minimum) through the preloadingmechanism and the dynamic load (the remaining 50 %)through the dynamic loading mechanism.7.5 After testing has begun, check the loading frequentlyunless the test machine is equippe
18、d with automatic loadmaintainers. Also check the specimens temperature to be surethat the loading rate is not heating the specimen more than 3C(5F).7.6 Record the maximum load and number of cycles tofailure.7.7 Specimens that have core-to-plate adhesive adhesionbond failures or adhesive cohesive fai
19、lures are not valid andshall be retested.8. Calculation8.1 Calculate the core shear stress in accordance with TestMethod C 273.t5PPb(1)where:t = core shear stress, MPa (psi);P = load on specimen, N (lb);L = length of specimen, mm (in.); andb = width of specimen, mm (in.).9. Report9.1 The report shal
20、l include the following:9.1.1 Description of test specimens; core material, adhesive,9.1.2 Dimensions and densities of the test specimens, coreorientation,9.1.3 Method of bonding specimens to plates; cure cycleand pressure,9.1.4 Description of test machines, including loading rate onstatic control s
21、pecimen and testing speed (number of cycles persecond) on fatigue test specimens and mode of testing (tensileor compressive).9.1.5 Testing conditions, including temperature and relativehumidity.9.1.6 Maximum load and maximum stress obtained on staticcontrol test, and a description of the type of fai
22、lure.9.1.7 Stress levels and stress ratio used in fatigue tests.9.1.8 Number of cycles to failure. If test is stopped at aspecified number of cycles without failure occurring, it shall beso noted.9.1.9 Acurve of maximum stress versus number of cycles tofailure (S-N curve) shall be plotted.10. Precis
23、ion and Bias10.1 PrecisionThe precision of the procedure in TestMethod C 394 for measuring sandwich core material shearfatigue is not available.10.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod, bias has not been determined.1
24、1. Keywords11.1 fatigue; sandwich core; shear strength; shear stressASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any
25、 such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are in
26、vited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not receive
27、d a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 394 00 (2008)2
