STM__D_412-98a-R2002.pdf

3.1.10 yield stress-the level of stress at the yield point.applied force is measured with the requisite accuracy during(D1566)the extension of the specimen to rupture.If the testing machineis not equipped with a recorder,a device shall be provided that4.Summary of Test Methodindicates,after rupture,the maximum force applied during4.1 The determination of tensile properties starts with testextension.Testing machine systems shall be capable of mea-pieces taken from the sample material and includes thesuring elongation of the test specimen in minimum incrementspreparation of the specimens and the testing of the specimens.of10%.Specimens may be in the shape of dumbbells,rings or straightNorE 2-A rate of elongation of 1000 100 mm/min(40 4 in./min)pieces of uniform cross-sectional area.may be used and notation of the speed made in the report.In case of4.2 Measurements for tensile stress,tensile stress at a givendispute,the test shall be repeated and the rate of elongation shall be at 500elongation,tensile strength,yield point,and ultimate elonga-50mm/min(202in.min).tion are made on specimens that have not been prestressed.6.2 Test Chamber for Elevated and Low Temperatures-TheTensile stress,yield point,and tensile strength are based on thetest chamber shall conform with the following requirements:original cross-sectional area of a uniform cross-section of thespecimen.6.2.1 Air shall be circulated through the chamber at a4.3 Measurement of tensile set is made after a previouslyvelocity of I to 2 m/s(3.3 to 6.6 fu/s)at the location of the gripsunstressed specimen has been extended and allowed to retractor spindles and specimens maintained within 2C(3.6F)of theby a prescribed procedure.Measurement of set after breakisspecified temperature.also described.6.2.2 A calibrated sensing device shall be located near thegrips or spindles for measuring the actual temperature.5.Significance and Use6.2.3 The chamber shall be vented to an exhaust system or5.1 All materials and products covered by these test meth-to the outside atmosphere to remove fumes liberated at highods must withstand tensile forces for adequate performance intemperatures.certain applications.These test methods allow for the measure-6.2.4 Provisions shall be made for suspending specimensment of such tensile properties.However,tensile propertiesvertically near the grips or spindles for conditioning prior toalone may not directly relate to the total end use performancetest.The specimens shall not touch each other or the sides ofof the product because of the wide range of potential perfor-the chamber except for momentary contact when agitated bymance requirements in actual use.the circulating air.5.2 Tensile properties depend both on the material and the6.2.5 Fast acting grips suitable for manipulation at high orconditions of test(extension rate,temperature,humidity,speci-low temperatures may be provided to permit placing dumbbellsmen geometry,pretest conditioning,etc.);therefore materialsor straight specimens in the grips in the shortest time possibleshould be compared only when tested under the same condi-to minimize any change in temperature of the chamber.tions.6.2.6 The dynamometer shall be suitable for use at the5.3 Temperature and rate of extension may have substantialtemperature of test or it shall be thermally insulated from theeffects on tensile properties and therefore should be controlled.chamber.These effects will vary depending on the type of material being6.2.7 Provision shall be made for measuring the elongationtested.of specimens in the chamber.If a scale is used to measure the5.4 Tensile set represents residual deformation which isextension between the bench-marks,the scale shall be locatedpartly permanent and partly recoverable after stretching andparallel and close to the grip path during specimen extensionretraction.For this reason,the periods of extension andand shall be controlled from outside the chamber.recovery(and other conditions of test)must be controlled to6.3 Dial Micrometer-The dial micrometer shall conform toobtain comparable results.the requirements of Practice D3767(Method A).For ringspecimens,see 14.10 of these test methods.6.Apparatus6.4 Apparatus for Tensile Set Test-The testing machine6.1 Testing Machine-Tension tests shall be made on adescribed in 6.1 or an apparatus similar to that shown in Fig.Ipower driven machine equipped to produce a uniform rate ofmay be used.A stop watch or other suitable timing devicegrip separation of 50050 mm/min(20+2 in./min)for ameasuring in minute intervals for at least 30 min,shall bedistance of at least 750 mm(30 in.)(see Note 1).The testingprovided.A scale or other device shall be provided formachine shall have both a suitable dynamometer and anmeasuring tensile set to within 1%indicating or recording system for measuring the applied forcewithin 2%.If the capacity range cannot be changed for a test7.Selection of Test Specimens(as in the case of pendulum dynamometers)the applied force atbreak shall be measured within+2%of the full scale value,7.1 Consider the following information in making selec-and the smallest tensile force measured shall be accurate totions:within 10%.If the dynamometer is of the compensating type7.1.1 Since anisotropy or grain directionality due to flowfor measuring tensile stress directly,means shall be provided tointroduced during processing and preparation may have anadjust for the cross-sectional area of the specimen.Theinfluence on tensile properties,dumbbell or straight specimensresponse of the recorder shall be sufficiently rapid that theshould be cut so the lengthwise direction of the specimen is+B+L.L.58n五8mPOOLSHAFT AND SUEIEDSHAFT WITH PINS-TO ENGAGE.SPOOI S_1E阳GAG程HGH4G六552岁：iparallel to the grain direction when this direction is known.7.1.4 Straight specimens tend to break in the grips if normalRing specimens normally give an average of with and acrossextension-to-break testing is conducted and should be usedthe grain properties.only when it is not feasible to prepare another type of7.1.2 Unless otherwise noted,thermoplastic rubber or ther-specimen.For obtaining non-rupture stress-strain or materialmoplastic elastomer specimens,or both,are to be cut frommodulus properties,straight specimens are quite useful.injection molded sheets or plaques with a thickness of 3.0+7.1.5 The size of specimen type used will be determined by0.3 mm.Specimens of other thickness will not necessarily givethe material,test equipment and the sample or piece availablecomparable results.Specimens are to be tested in directionsfor test.A longer specimen may be used for rubbers having lowboth parallel and perpendicular to the direction of flow in theultimate elongation to improve precision of elongation mea-mold.Sheet or plaque dimensions must be sufficient to do this.surement.7.1.3 Ring specimens enable elongations to be measured bygrip separation,but the elongation across the radial width of8.Calibration of the Testing Machinethe ring specimens is not uniform.To minimize this effect the8.1 Calibrate the testing machine in accordance with Proce-width of the ring specimens must be small compared to thedure A of Practice E 4.If the dynamometer is of the strain-gagediameter.type,calibrate the tester at one or more forces in addition to therequirements in Sections 7 and 18 of Practice E4.TestersTEST METHOD A-DUMBBELL AND STRAIGHThaving pendulum dynamometers may be calibrated as follows:SPECIMENS8.1.1 Place one end of a dumbbell specimen in the uppergrip of the testing machine.10.Apparatus8.1.2 Remove the lower grip from the machine and attach it,10.1 Die-The shape and dimensions of the die for prepar-by means of the gripping mechanism to the dumbbell specimening dumbbell specimens shall conform with those shown inin the upper grip.Fig.2.The inside faces in the reduced section shall be8.1.3 Attach a hook to the lower end of the lower specimenperpendicular to the plane formed by the cutting edges andgrip mechanism.polished for a distance of at least 5 mm(0.2 in.)from the8.1.4 Suspend a known mass from the hook of the lowercutting edge.The die shall at all times be sharp and free ofspecimen grip mechanism in such a way as to permit the massnicks(see 9.2).assembly to temporarily rest on the lower testing machine gripNorE 4-The condition of the die may be determined by investigatingframework or holder(see Note 2).the rupture point on any series of broken(ruptured)specimens.Remove8.1.5 Start the grip separation motor or mechanism,as insuch specimens from the grips of the testing machine,stack the joined-normal testing,and allow it to run until the mass is freelytogether specimens on top of each other,and note if there is any tendencysuspended by the specimen in the upper grip.for tensile breaks to occur at the same position on each of the specimens.8.1.6 If the dial or scale does not indicate the force appliedRupture consistently at the same place indicates that the die may be dull,nicked,or bent at that location.(or its equivalent in stress for a compensating type tester)within specified tolerance,thoroughly inspect the testing ma-10.2 Bench Marker-The two marks placed on the speci-chine for malfunction(for example,excess friction in bearingsmen and used to measure elongation or strain are called benchand other moving parts).Ensure that the mass of the lower gripmarks(see Note 4).The bench marker shall consist of a basemechanism and the hook are included as part of the knownplate containing two raised parallel projections.The surfaces ofmass.the raised projections(parallel to the plane of the base plate)8.1.7 After machine friction or other malfunction has beenare ground smooth in the same plane.The raised projectionremoved,recalibrate the testing machine at a minimum of threemarking surfaces shall be between 0.05 and 0.08 mm(0.002points using known masses to produce forces of approximatelyand 0.003 in.)wide and at least 15 mm(0.6 in.)long.The10,20 and 50%of capacity.If pawls or rachets are used duringangles between the parallel marking surfaces and the sides ofroutine testing,use them for calibration.Check for friction inthe projections shall be at least 75.The distance between thethe head by calibrating with the pawls up.centers of the two parallel projections or marking surfaces shallbe within 1 of the required or target bench mark distance.ANore 3-It is advisable to provide a means for preventing the knownhandle attached to the back or top of the bench marker basemass from falling to the floor in case the dumbbell should break.plate is normally a part of the bench marker.8.2 A rapid approximate calibration of the testing machineNore 5-If a contact extensometer is used to measure elongation.may be obtained by using a spring calibration device.bench marks are not necessary.10.3 Ink Applicator-A flat unyielding surface(hardwood,9.Test Temperaturemetal,or plastic)shall be used to apply either ink or powder to9.1 Unless otherwise specified,the standard temperature forthe bench marker.The ink or powder shall adhere to thetesting shall be 23 2C(73.4 3.6F).Specimens shall bespecimen,have no deteriorating effect on the specimen and beconditioned for at least 3 h when the test temperature is 23Cof contrasting color to that of the specimen.(73.4F).If the material is affected by moisture,maintain the10.4 Grips-The testing machine shall have two grips,onerelative humidity at 505%and condition the specimens forof which shall be connected to the dynamometer.at least 24 h prior to testing.When testing at any other10.4.1 Grips for testing dumbbell specimens shall tightentemperature is required use one of the temperatures listed inautomatically and exert a uniform pressure across the grippingPractice D 1349.surfaces,increasing as the tension increases in order to prevent9.2 For testing at temperatures above 23C(73.4F)preheatslippage and to favor failure of the specimen in the straightspecimens for 10+2 min for Method A and for 6+2 min forreduced section.Constant pressure pneumatic type grips alsoMethod B(see Note 3).Place each specimen in the testare satisfactory.At the end of each grip a positioning device ischamber at intervals ahead of testing so that all specimens of arecommended for inserting specimens to the same depth in theseries will be in the chamber the same length of time.Thegrip and for alignment with the direction of pull.preheat time at elevated temperatures must be limited to avoid10.4.2 Grips for testing straight specimens shall be constantadditional vulcanization or thermal aging.(Warning-In ad-pressure pneumatic,wedged,or toggle type designed to trans-dition to other precautions,suitable heat or cold resistantmit the applied gripping force over the entire width of thegloves should be worn for arm and hand protection whengripped specimen.testing at other than 23C(73.4F).A mask for the face is verydesirable for high temperature testing to prevent the inhalation11.Specimensof toxic fumes when the door of the chamber is open.)11.1 Dumbbell Specimens-Whenever possible,the test9.3 For testing at temperatures below 23C(73.4F)condi-specimens shall be injection molded or cut from a flat sheet nottion the specimens at least 10 min prior to testing.less than 1.3 mm(0.05 in.)nor more than 3.3 mm(0.13 in.)4D412-98a(2002)1118-226:前济只t无开TH(Rad)G(Rad)C+ZHR正A0iSSD日SECTION X-X2压U8学：二FIG.2 Standard Dies for Cutting Dumbbell Specimensthick and of a size which will permit cutting a specimen by one11.1.1 Marking Dumbbell Specimens-Dumbbell speci-of the standard methods(see Practice D3182).Sheets may bemens shall be marked with the bench marker described in 10.2.prepared directly by processing or from finished articles bywith no tension on the specimens at the time of marking.Markscutting and buffing.If obtained from a manufactured article,shall be placed on the reduced section,equidistant from itsthe specimen shall be free of surface roughness,fabric layers,center and perpendicular to the longitudinal axis.The betweenetc.in accordance with the procedure described in Practicebench mark distance shall be as follows:for Die C or Die D ofD 3183.All specimens shall be cut so that the lengthwiseFig.2.25.00 0.25 mm(1.000.01 in.);for any other Dieportion of the specimens is parallel to the grain unlessof Fig.2,50.000.5mm(2.000.02in).otherwise specified.In the case of sheets prepared in accor-11.1.2 Measuring Thickness of Dumbbell Specimens-dance with Practice D 3182,the specimen shall be 2.00.2Three measurements shall be made for the thickness,one at themm(0.08 0.008 in.)thick died out in the direction of thecenter and one at each end of the reduced section.The mediangrain.Use Die C,Fig.2(unless otherwise noted)to cut theof the three measurements shall be used as the thickness inspecimens from the sheet with a single impact stroke(hand orcalculating the cross sectional area.Specimens with a differ-machine)to ensure smooth cut surfaces.ence between the maximum and the minimum thickness