ASTM_D_5420_-_10.pdf

Designation:D542010Standard Test Method forImpact Resistance of Flat,Rigid Plastic Specimen by Meansof a Striker Impacted by a Falling Weight(Gardner Impact)1This standard is issued under the fixed designation D5420;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 relativeranking of materials according to the energy required to crackor break flat,rigid plastic specimens under various specifiedconditions of impact of a striker impacted by a falling weight.1.2 The values stated in SI units are to be regarded as thestandard.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.NOTE1There is no similar or equivalent ISO standard.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD2794 Test Method for Resistance of Organic Coatings tothe Effects of Rapid Deformation(Impact)D3763 Test Method for High Speed Puncture Properties ofPlastics Using Load and Displacement SensorsD4066 Classification System for Nylon Injection and Extru-sion Materials(PA)D4226 Test Methods for Impact Resistance of Rigid Poly-(Vinyl Chloride)(PVC)Building ProductsD5628 Test Method for Impact Resistance of Flat,RigidPlastic Specimens by Means of a Falling Dart(Tup orFalling Mass)D5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE171 Practice for Conditioning and Testing Flexible BarrierPackagingE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 DefinitionsFor definitions of plastics terms used inthis test method,see Terminologies D883 and D1600.3.2 Definitions of Terms Specific to This Standard:3.2.1 failure(of test specimen)the presence of any crackor split created by the impact of the falling weight that can beseen by the naked eye under normal laboratory lightingconditions.3.2.1.1 DiscussionFailure shall include the following:(1)complete shattering of the plaque;(2)any crack radiatingout toward the edges of the plaque on either surface of theplaque;(3)any radial crack within or just outside the impactarea of the striker;(4)any hole in the plaque,whether due tobrittle or ductile puncture,where unobstructed light or watercould pass through;(5)any brittle splitting of the bottomsurface of the plaque;and(6)any glassy-type chip dislodgedfrom or loosened from the plaque.3.2.1.2 DiscussionSince the interpretation of failure maybe slightly different between material types,refer to theappropriate material specification for guidance.3.2.1.3 DiscussionCracks usually start at the surface op-posite the one that is struck.For example,in some casesincipient cracking in glass-reinforced polymers is difficult todifferentiate from the reinforcing fibers.In such cases,apply apenetrating dye such as gentian violet to the stressed surface todetermine the onset of crack formation.3.2.2 mean-failure energy(mean impact resistance)theenergy required to produce 50%failures,equal to the productof the constant mass and mean failure height.3.2.3 mean-failure height(impact-failure height)theheight at which a standard mass,when dropped on testspecimens,will cause 50%failures.1This 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 July 1,2010.Published July 2010.Originally approvedin 1993.Last previous edition approved in 2004 as D5420-04.DOI:10.1520/D5420-10.2For 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 4.Summary of Test Method4.1 In this test method,a weight falls through a guide tubeand impacts a striker resting on top of a supported specimen.The fixed weight is dropped from various heights(see Fig.1).4.2 The procedure determines the energy(mass grav-ity height)that will cause 50%of the specimens tested to fail(mean-failure energy).4.3 The technique used to determine mean-failure energy iscommonly called the Bruceton Staircase Method,or theUp-and-Down Method(1).3Testing is concentrated near t