1、Designation: F 2183 02Standard Test Method forSmall Punch Testing of Ultra-High Molecular WeightPolyethylene Used in Surgical Implants1This standard is issued under the fixed designation F 2183; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the year of last revision. 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 mechanicalbehavior of ultra-high molecular weigh
3、t 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 r
4、adiation 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,
5、 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 t
6、ensile testing specified formedical grade UHMWPE by Specification F 648.1.3 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 irradiat
7、ion(1). The test method is also well suited for characterization ofUHMWPE before and after accelerated aging (for example,Guide F 2003), 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 be
8、en applied to other polymers,including polymethyl methacrylate (PMMA) bone cement,polyacetal, and high density polyethylene (HDPE) (8,9). How-ever, the small punch testing of polymers other than UHMWPEis beyond the scope of this standard.1.5 This standard does not purport to address all of thesafety
9、 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:D 695 Method for Compressive Proper
10、ties of Rigid Plas-tics3D 883 Terminology Relating to Plastics3E 4 Practices for Force Verification of Testing Machines4E 83 Practice for Verification and Classification of Exten-someters4F 648 Specification of Ultra-High Molecular Weight Poly-ethylene Powder and Fabricated Forms for Surgical Im-pla
11、nts5F 1714 Guide for Gravimetric Wear Assessment of Pros-thetic Hip Designs in Simulator Devices5F 1715 Guide for Wear Assessment of Prosthetic KneeDesigns in Simulator Devices5F 2003 Guide for Accelerated Aging of Ultra-High Molecu-lar Weight Polyethylene5F 2102 Guide for Evaluating the Extent of O
12、xidation inUltra-High-Molecular-Weight Polyethylene FabricatedForms Intended for Surgical Implants53. Terminology3.1 DefinitionsThe features of a typical small punch testload versus displacement curve for UHMWPE are illustrated inFig. 1.3.1.1 peak loadan initial local maximum in the loadversus displ
13、acement curve (Fig. 1). In certain radiationcrosslinked 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 mechanic
14、al test speci-mens, is disk-shaped, and is loaded axisymmetrically inbending by a hemispherical-head punch.3.1.3 ultimate displacementthe displacement at rupture(failure) of the specimen (Fig. 1).3.1.4 ultimate loadthe load at rupture (failure) of thespecimen (Fig. 1).1This test method is under the
15、jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devicesand is the direct responsibility of SubcommitteeF04.15on Materials Test Methods.Current edition approved April 10, 2002. Published June 2002.2The boldface numbers in parentheses refer to the list of references at the end
16、ofthis standard.3Annual Book of ASTM Standards, Vol 08.01.4Annual Book of ASTM Standards, Vol 03.01.5Annual Book of ASTM Standards, Vol 13.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.5 work to failurethe area under the loa
17、d versus dis-placement curve (Fig. 1).4. Significance and Use4.1 Miniature specimen testing techniques are used to char-acterize the mechanical behavior of UHMWPE stock materialsand surgical implants after manufacture, sterilization, shelfaging, radiation crosslinking, thermal treatment, and implant
18、a-tion (1). Furthermore, experimental UHMWPE materials canbe evaluated after accelerated aging and hip or knee wearsimulation. Consequently, the small punch test makes it pos-sible to examine relationships between wear performance andmechanical behavior of UHMWPE. This test method can alsobe used to
19、 rank the mechanical behavior of UHMWPE relativeto a reference control material (such as the NIST Ultra-HighMolecular Weight Polyethylene Reference Material #8456).4.2 Small punch testing results may vary with specimenpreparation and with the speed and environment of testing.Consequently, where prec
20、ise comparative results are desired,these factors must be carefully controlled.5. Apparatus5.1 Small Punch Test Apparatus6A system consisting of ahemispherical head punch, a die, and a guide for the punch, asshown in Fig. 2. The parts shall be fabricated from a hardenedsteel.5.1.1 GuideThe function
21、of the guide is to align the punchrelative to the specimen, which rests in a disk-shaped recess.The inner diameter of the guide bore shall be 0.1010 +0.0002/-0.0000 in. (2.565 +0.005/-0.000 mm), and the specimen recessshall be 0.0200 +0.0004/-0.0000 in. (0.508 +0.010/-0.000 mm)in depth and 0.2520 6
22、0.0005 in. (6.401 6 0.013 mm) indiameter.5.1.2 DieThe function of the die is to constrain the sampleduring testing. The inner diameter of the die bore shall be0.1500 6 0.0005 in. (3.810 6 0.013 mm).5.1.3 PunchThe hemispherical head punch shall have adiameter of 0.1000 in. (2.540 mm), with a toleranc
23、e of+0.0000/-0.0002 in. (+0.000/-0.005 mm).5.2 Testing MachineAny suitable testing machine as de-scribed in Method D 695, consisting of a drive mechanism anda load indicator. The load indicator shall have a full range of250 N (56.2 lbs). The accuracy of the machine shall be verifiedat least once per
24、 year, as specified by Method D 695 andPractice E 4.5.3 CompressometerThis instrument, described in Sec-tion 5.2 from Method D 695, can be used to determine thedistance between the die and the punch during the test. If theactuator displacement of the testing machine can be shown todetermine punch di
25、splacement within 1 % of the value mea-sured by a suitably calibrated compressometer (as defined inPractice E 83), actuator displacement shall be used as refer-ence.5.4 Compression PlatenThe punch shall rest on a com-pression platen or tool for applying the load to the punch.5.5 MicrometersSuitable
26、micrometers, reading to 0.0001in. (0.0025 mm), shall be used to record the diameter andthickness of the specimens.5.6 ThermometerA suitable thermometer or thermo-couple, reading to 0.1C, shall be used to record the testtemperature within the range 20 to 24C.6. Test Specimens6.1 As the test results a
27、re known to be sensitive to prepa-ration technique, the specimens described in 6.2 and 6.3 shallbe used. The specimens may be prepared by machiningoperations from materials in sheet, rod, plate, or implant form.All machining operations shall be done carefully so thatsmooth surfaces result. Great car
28、e shall be taken in machiningthe faces so that smooth, parallel surfaces result.NOTE 1Although specimen fabrication methods other than machining(for example, microtoming) may be used, the use of alternate specimenpreparation methods have not yet been shown to provide equivalent testresults to machin
29、ed specimens.6.2 If specimens are prepared from stock UHMWPE mate-rials, the orientation of the test specimen with respect to themanufacturing direction (for example, perpendicular to the6Small punch testers suitable for use and meeting the requirements of this testmethod are available from Exponent
30、, Inc., 2300 Chestnut St., Suite 150, Philadel-phia, PA, 19103.FIG. 1 Features of the Small Punch Test Load Versus Displacement Curve for Unirradiated UHMWPE, Including the Peak Load, UltimateLoad and Displacement, and Work to FailureF 21832extrusion or compression molding axis) shall be recorded,al
31、ong with the distance from the surface of the stock material.If the specimens are machined directly from actual implants,the orientation and depth from the articulating surface shall berecorded.6.3 The standard test specimen shall have a thickness of0.0200 +0.0002/-0.0003 in. (0.508 +0.005/-0.008 mm
32、) and adiameter of 0.250 +0.000/-0.005 in. (6.350 +0.000/-0.127mm).6.4 Specimens falling outside the dimensional tolerancesspecified in 6.2 shall be discarded.7. Number of Test Specimens7.1 A minimum of five specimens per material condition isrecommended, especially for thermally treated and highlyc
33、rosslinked UHMWPE materials. However, due to the repeat-ability of the test as reported in the literature, four specimensper material condition may be sufficient to establish significantdifferences between unirradiated UHMWPE material groups.8. Speed of Testing8.1 The test results are sensitive to t
34、esting speed. Therefore,the speed of the testing machine shall be calibrated to within1 % accuracy at least once per year, as specified in MethodD 695.8.2 The reference speed for small punch testing shall be 0.5mm min-1, unless otherwise indicated by the customer orspecification.9. Conditioning9.1 C
35、ondition the test specimens at 23 6 2C for at least 1h prior to testing, unless otherwise specified by the customer orspecification.9.2 The small punch test results are sensitive to test tem-perature. Therefore, conduct tests in the standard laboratoryconditions of 23 6 2C, unless otherwise indicate
36、d by thecustomer or specification. In cases of disagreement, the toler-ances shall be 1C (1.8F).9.3 UHMWPE is a nonpolar, hydrophobic polymer. Conse-quently, relative humidity is not expected to play a major rolein the results of the small punch testing of UHMWPE.10. Procedure10.1 Specimens are plac
37、ed within the aforementioned speci-men recess in the punch guide. The specimen guide, die, andpunch are mounted within a testing frame.10.2 Mechanical testing is performed in bending by inden-tation of the disk-shaped UHMWPE specimens with thehemispherical head steel punch. The specimen is loaded by
38、 thehemispherical head punch moving into the specimen at aconstant displacement rate until failure of the specimen occurs.10.3 The load applied to the punch, as well as the displace-ment of the punch, are recorded continuously during the test.10.4 Failure of the specimen and termination of the test
39、willbe indicated by a load drop in the load versus displacementcurve, or when the ultimate load drops to 5 N.FIG. 2 Schematic of the Small Punch Test Apparatus, Including the Die, Guide, Hemispherical Head Punch, and Miniature Disk ShapedSpecimenF 2183311. Calculations11.1 Calculate the initial peak
40、 load (if applicable), theultimate load, ultimate displacement, and work to failure asshown in Fig. 1. The units for the initial peak load and ultimateload shall be in newtons. Ultimate displacement shall bereported in millimetres, and the work to failure shall bereported in millijoules.11.2 For eac
41、h of the small punch test metrics, calculate tothree significant figures the arithmetic mean of all valuesobtained and report as the “average value” for the particularmetric in question.11.3 Calculate the standard deviation (estimated) and reportto two significant figures.12. Report12.1 Report the f
42、ollowing information:12.1.1 Complete identification of the material tested, includ-ing type, source, manufacturers lot number, form, irradiationlevel, sterilization method, shelf age, and so forth,12.1.2 Method of preparing test specimens,12.1.3 Specimen dimensions,12.1.4 Conditioning procedure used
43、,12.1.5 Temperature in test room,12.1.6 Number of specimens tested,12.1.7 Orientation and location of specimens with respect tooriginal stock material or implant,12.1.8 Speed of testing,12.1.9 Average value and standard deviation for initial peakload (if present on the load displacement curve),12.1.
44、10 Average value and standard deviation for ultimateload,12.1.11 Average value and standard deviation for ultimatedisplacement,12.1.12 Average value and standard deviation for work tofailure,12.1.13 Date of test, and12.1.14 Date of test method.13. Precision and Bias13.1 PrecisionThe repeatability of
45、 the small punch testmetrics is reported in the literature to be less than 10 % forvirgin, unirradiated UHMWPE materials (1). An interlabora-tory study is currently planned to provide quantification ofreproducibility.13.2 BiasThere are no recognized standards on which tobase an estimate of bias for
46、this test standard.14. Keywords14.1 mechanical behavior; miniature specimens; smallpunch test; UHMWPE; ultra-high molecular weight polyeth-yleneREFERENCES(1) Edidin, A. A. and Kurtz, S. M., “Development and Validation of theSmall Punch Test for UHMWPE Used in Total Joint Replacements,” InFunctional
47、Biomaterials, Eds. N. Katsube, W. Soboyejo and M. Sacks.Winterthur, Switzerland: Trans Tech Publications Ltd., 2001.(2) Kurtz, S. M., Foulds, J. R., Jewett, C. W., Srivastav, S., and Edidin, A.A., “Validation of a Small Punch Testing Technique to Characterize theMechanical Behavior of Ultra-High Mol
48、ecular Weight Polyethylene,”Biomaterials, Vol 18, 1997, pp. 1659-1663.(3) Kurtz, S. M., Pruitt, L. A., Jewett, C. W., Foulds, J. R., and Edidin, A.A., “Radiation and Peroxide Crosslinking Promote Strain HardeningBehavior and Molecular Alignment in UHMWPE During MultiaxialLoading Conditions,” Biomate
49、rials, Vol 20, 1999, pp. 1449-1462.(4) Kurtz, S. M., Jewett, C. W., Foulds, J. R., and Edidin, A. A., “AMiniature-Specimen Mechanical Testing Technique Scaled to theArticulating Surface of Polyethylene Components for Total JointArthroplasty,” J Biomed Mater Res (Appl Biomater), Vol 48, 1999, pp.75-81.(5) Edidin, A. A., Rimnac, C. M., Goldberg, V., and Kurtz, S. M.,“Mechanical Behavior, Wear Surface Morphology, and Clinical Per-formance of UHMWPE Acetabular Components after 10 Years ofImplantation,” Wear, Vol 250, 2001, pp. 152-158.(6) Kurtz, S. M., Rimnac, C. M., P
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