Material characterization at high strain by adapted tensile tests

Abstract

The strength of materials at high strain levels has\ud been determined using the so-called Continuous-Bendingunder-\ud Tension (CBT) test. This is a modified tensile test\ud where the specimen is subjected to repetitive bending at the\ud same time. This test enables to create high levels of uniform\ud strain. A wide variety of materials has been tested this way.\ud The strength of the material after CBT testing has been\ud measured in different ways: by secondary tensile tests, by\ud interrupted CBT tests, and directly from the fracture in the\ud CBT test. All methods yield similar results: the strength is\ud largely unaffected by the cyclic pre-deformation and mainly\ud depends on the overall increase in length. Only for multiphase\ud materials the strength shows a minor influence of\ud CBT test conditions. The hardening follows the extrapolated\ud hardening observed in a conventional tensile test, except for\ud brass. This test method can potentially be used for measuring\ud hardening curves at high strain levels