ASTM C480-1999(2005) Standard Test Method for Flexure Creep of Sandwich Constructions《夹层结构挠曲蠕变的标准试验方法》.pdf

1、Designation: C 480 99 (Reapproved 2005)Standard Test Method forFlexure Creep of Sandwich Constructions1This standard is issued under the fixed designation C 480; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi

2、sion. 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 the determination of the creepcharacteristics and creep rate of sandwich constructions loadedin flexur

3、e, at any desired temperature.1.2 The values stated in 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 stand

4、ard 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:2C 393 Test Method for Flexural Properties of SandwichConstructions3. Significance and Use3.1 The determination of the creep rat

5、e provides informa-tion on the behavior of sandwich constructions under constantload. Creep is defined as deflection under constant load over aperiod of time beyond the initial deformation as a result of theapplication of the load. Deflection data obtained from this testmethod can be plotted against

6、 time, and a creep rate deter-mined. By using standard specimen constructions and constantloading, the test method may also be used to evaluate creepbehavior of sandwich panel core-to-facing adhesives.3.2 This test method provides a standard method of obtain-ing flexure creep of sandwich constructio

7、ns for quality control,acceptance specification testing, and research and develop-ment.4. Apparatus4.1 The apparatus for loading the specimen shall conform toTest Method C 393 except that a constant load shall be appliedby means of weights and a lever system. Fig. 1 shows a leverand weight-loading a

8、pparatus that has been found satisfactory.4.2 Micrometer, gage, or caliper, capable of measuringaccurately to 0.025 mm (0.001 in.).5. Test Specimens5.1 The test specimen shall be of sandwich construction ofa size and proportions conforming to the flexure test specimendescribed in Test Method C 393.5

9、.2 The number of test specimens and the method of theirselection depend on the purpose of the particular test underconsideration, and no general rule can be given to cover allcases. However, when specimens are to be used for acceptancetests, at least three specimens shall be tested.6. Conditioning6.

10、1 When the test is performed at room temperature and thephysical properties of the component materials are affected bymoisture, bring the test specimens to constant weight (61%)before testing, preferably in a conditioning room with tempera-ture and humidity control. The tests, preferably, should bem

11、ade in a room under the same conditions.Atemperature of 236 3C (73 6 5F) and a relative humidity of 50 6 5 % arerecommended for standard control conditions.7. Procedure7.1 Measure the dimensions of the specimens in millimetres(inches) to a precision of 60.5 %.7.2 The load applied to the specimen by

12、the lever systemshown in Fig. 1 may be calculated as follows:P 5WM1 wBA1 p (1)where:P = load applied to specimen, N (lb);W = weight (including tray mass), N (lb);M = distance between pivot point and weight point, mm(in.);w = mass of lever arm, N (lb);p = mass of loading plate and rod, N (lb);B = dis

13、tance from pivot point to center of gravity of theloading arm, mm (in.); andA = distance between pivot point and load point, mm (in.).1This specification is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.09 onSandwich Construct

14、ion.Current edition approved Mar. 1, 2005. Published March 2005. Originallyapproved in 1961. Last previous edition approved in 1999 as C 480 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards v

15、olume 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 Attach the weight tray to the lever arm and support ittemporarily so that no load is applied to th

16、e specimen. If thetest is to be conducted at an elevated temperature, place theapparatus and specimen in the oven and bring the oven up tothe desired test temperature. Allow sufficient time for the ovenand specimen to stabilize at the test temperature. Remove thetemporary support and apply the load

17、slowly.7.4 Measure deflections to the nearest 0.025 mm (0.001 in.).Read the initial deflection and record it. Take deflectionreadings at sufficient time intervals (Note 1) to define com-pletely a creep curve with deflection plotted as the ordinate andtime as the abscissa.NOTE 1A recommended procedur

18、e is to take readings at 10-minintervals for the first hour, then at hourly intervals up to 7 h. After this,readings may be taken at any desired interval, such as twice a day, until thetotal test time has been reached or failure has occurred.8. Calculations8.1 Calculate the creep deflection rate in

19、millimetres(inches) per hour or millimetres (inches) per day for anyportion of the curve (beyond the initial deformation) byobtaining the difference of the two deflections and dividing bythe period of time.8.2 For comparison of materials, the creep deflection maybe expressed as a percentage of the i

20、nitial deflection after aperiod of time as follows:Creep, % of original deflection 5D 2 dd3 100 (2)where:D = total deflection under constant load at time t, mm (in.)andd = initial static deflection under the same load and at thesame temperature, mm (in.).9. Report9.1 The report shall include the fol

21、lowing:9.1.1 Description of the test specimens; facings, core, andcore-to-facing adhesive,9.1.2 Dimensions of the test specimens, core orientation,9.1.3 Test conditions including apparatus, test temperature,span, loads, and test time,9.1.4 Bending stress in the facings and shear stress in thecore ca

22、lculated for the applied load in accordance with TestMethod C 393,9.1.5 Creep deflection curve, and9.1.6 Type and location of failure, if any, such as excessivecreep in the adhesive, core shear, and so forth.10. Precision and Bias10.1 Precision It is not possible to specify the precision ofthe proce

23、dure in Test Method C 480 for measuring the sand-wich panel creep deflection because of the unavailability ofconsistent samples for testing.10.2 Since there is no accepted reference material suitablefor determining the bias for the procedure in this test method,bias has not been determined.11. Keywo

24、rds11.1 creep; creep deflection; sandwich; sandwichconstructionASTM 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 such

25、 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 invited

26、 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 received a f

27、air 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).FIG. 1 Creep Test Apparatus and Loading SystemC 480 99 (2005)2