1、Designation: F2183 02 (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 o
2、r, 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
3、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 i
4、mplants 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 o
5、f 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
6、 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
7、 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 punc
8、h 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 regarde
9、d 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
10、 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
11、 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 Sim
12、ulator 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
13、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 of ASTM Committee F04 on Medicaland Surgical Materials and Devicesand is the direct
14、 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 th
15、e 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 hist
16、orical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesNOTICE: This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International (www.astm.org) for the
17、latest information13.1.1 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 t
18、esta test wherein the specimen is ofminiature size relative to conventional mechanical testspecimens, 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
19、 load at rupture (failure) of thespecimen (Fig. 1).3.1.5 work to failurethe area under the load 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
20、manufacture, sterilization, shelfaging, radiation crosslinking, thermal treatment, and implanta-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
21、between wear performance andmechanical behavior of UHMWPE. This test method can alsobe used to 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 w
22、ith specimenpreparation and with the speed and environment of testing.Consequently, where precise comparative results are desired,these factors must be carefully controlled.5. Apparatus5.1 Small Punch Test Apparatus5A system consisting of ahemispherical head punch, a die, and a guide for the punch,
23、asshown in Fig. 2. The parts shall be fabricated from a hardenedsteel.5.1.1 GuideThe function 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 spe
24、cimen recessshall be 0.0200 +0.0004/-0.0000 in. (0.508 +0.010/-0.000 mm)in depth and 0.2520 6 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 Pu
25、nchThe hemispherical head punch shall have adiameter of 0.1000 in. (2.540 mm), with a tolerance of+0.0000/-0.0002 in. (+0.000/-0.005 mm).5.2 Testing MachineAny suitable testing machine as de-scribed in Method D695, consisting of a drive mechanism anda load indicator. The load indicator shall have a
26、full range of250 N (56.2 lbs). The accuracy of the machine shall be verifiedat least once per year, as specified by Method D695 andPractice E4.5.3 CompressometerThis instrument, described in Section5.2 from Method D695, can be used to determine the distancebetween the die and the punch during the te
27、st. If the actuatordisplacement of the testing machine can be shown to determinepunch displacement within 1 % of the value measured by asuitably calibrated compressometer (as defined in PracticeE83), actuator displacement shall be used as reference.5Small punch testers suitable for use and meeting t
28、he requirements of this testmethod are available from Exponent, Inc., 2300 Chestnut St., Suite 150,Philadelphia, 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 FailureF2183
29、02 (2008)25.4 Compression PlatenThe punch shall rest on a com-pression platen or tool for applying the load to the punch.5.5 MicrometersSuitable micrometers, reading to 0.0001in. (0.0025 mm), shall be used to record the diameter andthickness of the specimens.5.6 ThermometerA suitable thermometer ort
30、hermocouple, 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 are 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
31、 from materials in sheet, rod, plate, or implant form.All machining operations shall be done carefully so thatsmooth surfaces result. Great care shall be taken in machiningthe faces so that smooth, parallel surfaces result.NOTE 1Although specimen fabrication methods other than machining(for example,
32、 microtoming) may be used, the use of alternate specimenpreparation methods have not yet been shown to provide equivalent testresults to machined specimens.6.2 If specimens are prepared from stock UHMWPEmaterials, the orientation of the test specimen with respect tothe manufacturing direction (for e
33、xample, perpendicular to theextrusion or compression molding axis) shall be recorded,along 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 te
34、st specimen shall have a thickness of0.0200 +0.0002/-0.0003 in. (0.508 +0.005/-0.008 mm) 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 speci
35、mens per material condition isrecommended, especially for thermally treated and highlycrosslinked 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 unirrad
36、iated UHMWPE material groups.8. Speed of Testing8.1 The test results are sensitive to testing speed. Therefore,the speed of the testing machine shall be calibrated to within1 % accuracy at least once per year, as specified in MethodD695.8.2 The reference speed for small punch testing shall be 0.5mm
37、min-1, unless otherwise indicated by the customer orspecification.9. Conditioning9.1 Condition the test specimens at 23 6 2C for at least 1h prior to testing, unless otherwise specified by the customer orspecification.FIG. 2 Schematic of the Small Punch Test Apparatus, Including the Die, Guide, Hemi
38、spherical Head Punch, and Miniature Disk ShapedSpecimenF2183 02 (2008)39.2 The small punch test results are sensitive to test tem-perature. Therefore, conduct tests in the standard laboratoryconditions of 23 6 2C, unless otherwise indicated by thecustomer or specification. In cases of disagreement,
39、the toler-ances shall be 1C (1.8F).9.3 UHMWPE is a nonpolar, hydrophobic polymer.Consequently, relative humidity is not expected to play a majorrole in the results of the small punch testing of UHMWPE.10. Procedure10.1 Specimens are placed within the aforementioned speci-men recess in the punch guid
40、e. 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 thehemispherical head punch moving into the specimen at aconst
41、ant 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 willbe indicated by a load drop in the load versus displacement
42、curve, or when the ultimate load drops to 5 N.11. Calculations11.1 Calculate the initial peak 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 be
43、reported in millimetres, and the work to failure shall bereported in millijoules.11.2 For each 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 st
44、andard deviation (estimated) and reportto two significant figures.12. Report12.1 Report the following 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 Met
45、hod of preparing test specimens,12.1.3 Specimen dimensions,12.1.4 Conditioning procedure used,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
46、and standard deviation for initial peakload (if present on the load displacement curve),12.1.10 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
47、test, and12.1.14 Date of test method.13. Precision and Bias13.1 PrecisionThe repeatability of 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 ofreprod
48、ucibility.13.2 BiasThere are no recognized standards on which tobase an estimate of bias for this test standard.14. Keywords14.1 mechanical behavior; miniature specimens; smallpunch test; UHMWPE; ultra-high molecular weight polyeth-yleneF2183 02 (2008)4REFERENCES(1) Edidin, A. A. and Kurtz, S. M., “
49、Development and Validation of theSmall Punch Test for UHMWPE Used in Total Joint Replacements,”In Functional 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 Characterizethe Mechanical Behavior of Ultra-High Molecular WeightPolyethylene,” Biomaterials, Vol 18, 1997, pp. 16591663.(3) Kurtz, S. M., Pruitt, L. A., Jewett, C. W., Foulds, J. R.,
