ASTM_D_2990_-_09.pdf

Designation:D299009Standard Test Methods forTensile,Compressive,and Flexural Creep and Creep-Rupture of Plastics1This standard is issued under the fixed designation D2990;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 These test methods cover the determination of tensileand compressive creep and creep-rupture of plastics underspecified environmental conditions(see 3.1.3).1.2 While these test methods outline the use of three-pointloading for measurement of creep in flexure,four-point loading(which is used less frequently)can also be used with theequipment and principles as outlined in Test Methods D790.1.3 For measurements of creep-rupture,tension is the pre-ferred stress mode because for some ductile plastics rupturedoes not occur in flexure or compression.1.4 Test data obtained by these test methods are relevant andappropriate for use in engineering design.1.5 The values stated in SI units are to be regarded as thestandard.The values in parentheses are for information only.1.6 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 practices and determine the applica-bility of regulatory limitations prior to use.A specific warningstatement is given in 6.8.2.NOTE1This standard and ISO 899 Parts 1 and 2 address the samesubject matter,but differ in technical content(and results cannot bedirectly compared between the two test methods).ISO 899 Part 1addresses tensile creep and creep to rupture and ISO 899 Part 2 addressesflexural creep.Compressive creep is not addressed in ISO 899.2.Referenced Documents2.1 ASTM Standards:2D543 Practices for Evaluating the Resistance of Plastics toChemical ReagentsD618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD695 Test Method for Compressive Properties of RigidPlasticsD790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsD1822 Test Method for Tensile-Impact Energy to BreakPlastics and Electrical Insulating MaterialsD4000 Classification System for Specifying Plastic Materi-alsD4065 Practice for Plastics:Dynamic Mechanical Proper-ties:Determination and Report of ProceduresD4968 Guide for Annual Review of Test Methods andSpecifications for PlasticsD5947 Test Methods for Physical Dimensions of SolidPlastics Specimens3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 creep modulusthe ratio of initial applied stress tocreep strain.3.1.2 creep strainthe total strain,at any given time,produced by the applied stress during a creep test.3.1.2.1 DiscussionThe term creep,as used in this testmethod,reflects current plastics engineering usage.In scientificpractice,creep is often defined to be the nonelastic portion ofstrain.However,this definition is not applicable to existingengineering formulas.Plastics have a wide spectrum of retar-dation times,and elastic portions of strain cannot be separatedin practice from nonelastic.Therefore,wherever“strain”ismentioned in these test methods,it refers to the sum of elasticstrain plus the additional strain with time.3.1.3 deformationa change in shape,size or position of atest specimen as a result of compression,deflection,or exten-sion:3.1.4 compressionin a compressive creep test,the de-crease in length produced in the gage length of a test specimen.3.1.5 deflectionin a flexural creep test,the change inmid-span position of a test specimen.1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.10 on MechanicalProperties.Current edition approved Sept.1,2009.Published September 2009.Originallyapproved in 1971.Last previous edition approved in 2001 as D2990-01.DOI:10.1520/D2990-09.2For 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 website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.6 extensionin a tensile creep test,the increase inlength produced in the gage length of a test specimen.3.1.7 slenderness ratiothe ratio of the length of a columnof uniform cross section to its least radius of gyration;forspecimens of uniform rectangular cross section,the radius ofgyration is 0.289 times the smaller cross-sectional dimension;for specimens of uniform circular cross section