![]() The tensile modulus is determined with directly measuring extensometers.The permitted error in strain determination is 0.0002 specified. The crosshead travel is especially used for determination of the nominal strain at break, so that the distances to be measured are relatively large. Values to be measured include the crosshead travel, or the change in clamping distance and the directly measured specimen elongation.įor measurement of the crosshead travel, ASTM D638 requires an accuracy of ± 10% relative to the respective measured value. This means you can measure the modulus values and tensile stress of many materials with the same test arrangement and without having to reconfigure the arrangement. ZwickRoell testing machines can achieve the measurement accuracy required in ASTM E4 starting at 1/1000 of their measurement range. The quality of a force measuring system is therefore particularly defined by the width of the measuring range over which the accuracy can be achieved. This requirement is verified with a calibration to ASTM E4 for the entire measurement range of the load cell. The ASTM D638 standard requires a measurement accuracy of ☑% for the measured value. As part of periodic calibration when compared to a measuring instrument based on national standards, evidence has shown that these measured values achieve a level of accuracy defined in the test standard across defined measuring ranges. The test specimen Type IV is ideal for testing of very soft polymers (e.g., rubber) and is used when comparing soft and more stiff polymers.įorce and extension are the two fundamental values measured by a testing machine.For sheet thickness of more than 14 mm, the thickness is adjusted through mechanical processing. Here, the width of the narrow parallel section, as well as the shoulder width and the overall length are increased so that the specimen thickness remains less than the width. If specimens with material thicknesses of more than 7 mm can be obtained through mechanical processing, then specimen Type III is used.If only a small amount of material is available, or if removal from a component does not allow for a larger specimen, then a specimen Type V is used, which is reduced in every dimension relative to Type I.Provided that by using the test specimen Type I a fracture cannot be produced in the narrow parallel part of the specimen, ASTM D638 recommends the use of a test specimen Type II, in which the width of the narrow parallel section is significantly reduced.The preferred test specimen is the dumbbell Type I, which with a thickness of 3.2 mm (1/8 inch) and a gauge length of 50 mm (2 inches) is still relatively similar to common component material thicknesses and at the same time allows for good strain measurement accuracy. ![]() Consultation and Application Technology.Specimen preparation and dimensional measurement.Extensometers for Compression, Flexure and Components Testing.Electromechanical static testing machines.Analog and Digital Hardness Testers to Shore.Extrusion Plastometers / Melt Flow Index Testers.Testing Machine for Tubular Biomaterials.Biaxial Testing Machine for Biomaterials.Materials testing machines with torsion drive.Electromechanical Servo Testing Actuators.Testing machine for high test loads (E-series).Intermediate products and finished parts. ![]()
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