ASTM_D_4812_-_11.pdf

Designation:D481211Standard Test Method forUnnotched Cantilever Beam Impact Resistance of Plastics1This standard is issued under the fixed designation D4812;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.Scope*1.1 This test method covers the determination of the resis-tance of plastics to breakage by flexural shock,as indicated bythe energy extracted from standardized pendulum-typehammers,mounted in standardized machines,in breakingstandard specimens with one pendulum swing.The result ofthis test method is reported as energy absorbed per unit ofspecimen width.NOTE1The pendulum-type test instruments have been standardizedin that they must comply with certain requirements,including a fixedheight of hammer fall that results in a substantially fixed velocity of thehammer at the moment of impact.Pendulums of different initial energies(produced by varying their effective weights)are recommended for usewith specimens of different impact strengths.Moreover,manufacturers ofthe equipment are permitted to use different lengths and constructions ofpendulums(with resulting possible differences in pendulum rigidities(seeSection 5),and other differences in machine design).1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE2This standard and ISO 180,Method U address the samesubject matter,but differ in technical content.2.Referenced Documents2.1 ASTM Standards:2D256 Test Methods for Determining the Izod PendulumImpact Resistance of PlasticsD618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 DefinitionsDefinitions used in this test method are inaccordance with Terminology D883.4.Summary of Test Method4.1 This test method differs from others of similar characterin that unnotched test specimens are used(see Test MethodsD256 for procedures using notched test specimens).The lackof a notch makes this test method especially useful forreinforced materials where a notch may mask the effects oforientation.It may also be used with other filled or unrein-forced materials where a stress-concentrating notch is notdesired.It is not valid for materials that twist when subjectedto this test.5.Significance and Use5.1 The pendulum-impact test indicates the energy to breakstandard test specimens of specified size under stipulatedconditions of specimen mounting and pendulum velocity atimpact.5.2 The energy lost by the pendulum during the breakage ofthe specimen is the sum of the energies required to produce thefollowing results:5.2.1 To initiate fracture of the specimen,5.2.2 To propagate the fracture across the specimen,5.2.3 To throw the free end(or pieces)of the brokenspecimen(toss correction),5.2.4 To bend the specimen,5.2.5 To produce vibration in the pendulum arm,5.2.6 To produce vibration or horizontal movement of themachine frame or base,5.2.7 To overcome friction in the pendulum bearing and inthe indicating mechanism,and to overcome windage(pendu-lum air drag),5.2.8 To indent or deform plastically the specimen at theline of impact,and5.2.9 To overcome the friction caused by the rubbing of thestriking nose(or other part of the pendulum)over the face ofthe bent specimen.5.3 For relatively brittle materials for which fracture propa-gation energy is small in comparison with the fracture initiation1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved Dec.1,2011.Published January 2012.Originallyapproved in 1988.Last previous edition approved in 2006 as D4812-06.DOI:10.1520/D4812-11.2For 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 energy,the indicated impact energy absorbed is,for allpractical purposes,the sum of items given in 5.2.1 and 5.2.3.The toss correction(5.2.3)may represent a very large fractionof the total energy absorbed when testing relatively d