A critical analysis of plastic flow behaviour in axisymmetric isothermal and Gleeble compression testing

Coupled thermo-mechanical finite element modelling of both isothermal axisymmetric compression and compression testing using the Gleeble thermo-mechanical simulator has been carried out in order to compare the levels of relative stress error which can arise during each test. A Norton-Hoff material model has been used as a basis for evaluating the testing methods and the calculation of the relative error by providing reference stress–strain curves. The errors arise from effects such as interface friction causing non-uniform deformation fields and heat generation in both testing cases and from initial specimen temperature profiles in the case of the Gleeble testing. These errors are shown to be up to approximately 20% and vary throughout the test from positive to negative and are therefore important to consider when processing experimental data.