ASTM_F_2183_-_02_2008.pdf

Designation:F218302(Reapproved 2008)Standard Test Method forSmall Punch Testing of Ultra-High Molecular WeightPolyethylene Used in Surgical Implants1This standard is issued under the fixed designation F2183;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.1.Scope1.1 This test method covers the determination of mechanicalbehavior of ultra-high molecular weight polyethylene(UHM-WPE)by small punch testing of miniature disk specimens(0.5mm in thickness and 6.4 mm in diameter).The test method hasbeen established for characterizing UHMWPE surgical mate-rials after ram extrusion or compression molding(1,2)2;forevaluating as-manufactured implants after radiation crosslink-ing and sterilization(3,4);as well as for testing of implants thathave been retrieved(explanted)from the human body(5,6).1.2 The parameters of the small punch test,namely the peakload,ultimate displacement,ultimate load,and work to failure,provide metrics of the yielding,ultimate strength,ductility,andtoughness of UHMWPE under multiaxial loading conditions.Because the mechanical behavior of UHMWPE is differentwhen loaded under uniaxial and multiaxial loading conditions(3),the small punch test provides a complementary mechanicaltesting technique to the uniaxial tensile testing specified formedical grade UHMWPE by Specification F648.1.3 In addition to its use as a research tool in implantretrieval analysis,the small punch test can be used as alaboratory screening test to evaluate new UHMWPE materials,such as those created by gamma or electron beam irradiation(1).The test method is also well suited for characterization ofUHMWPE before and after accelerated aging(for example,Guide F2003),and in that regard it can provide ranking of themechanical degradation of different UHMWPE samples afteroxidative degradation(4,7).1.4 The small punch test has been applied to other polymers,including polymethyl methacrylate(PMMA)bone cement,polyacetal,and high density polyethylene(HDPE)(8,9).However,the small punch testing of polymers other thanUHMWPE is beyond the scope of this standard.1.5 The values stated in SI units are to be regarded asstandard.The units in parentheses are mathematical conver-sions to inch-pound units that are provided for informationonly and are not considered standard.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.2.Referenced Documents2.1 ASTM Standards:3D695 Test Method for Compressive Properties of RigidPlasticsD883 Terminology Relating to PlasticsE4 Practices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Exten-someter SystemsF648 Specification for Ultra-High-Molecular-Weight Poly-ethylene Powder and Fabricated Form for Surgical Im-plantsF1714 Guide for Gravimetric WearAssessment of ProstheticHip Designs in Simulator DevicesF1715 Guide for Wear Assessment of Prosthetic Knee De-signs in Simulator Devices(Withdrawn 2006)4F2003 Practice for Accelerated Aging of Ultra-High Mo-lecular Weight Polyethylene after Gamma Irradiation inAirF2102 Guide for Evaluating the Extent of Oxidation inPolyethylene Fabricated Forms Intended for SurgicalImplants3.Terminology3.1 DefinitionsThe features of a typical small punch testload versus displacement curve for UHMWPE are illustrated inFig.1.1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devicesand is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved May 1,2008.Published June 2008.Originallyapproved in 2002.Last previous edition approved in 2002 as F2083 02.DOI:10.1520/F2183-02R08.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For 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.4The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.1 peak loadan initial local maximum in the loadversus displacement curve(Fig.1).In certain radiation cross-linked UHMWPE materials,the load versus displacementcurve increases monotonically and a shoulder,rather than aninitial peak load,may be observed.3.1.2 small punch testa test wherein the specimen is ofminiature size relative to conventional mechanical testspecimens,is disk-shaped,and is loaded