GENERALIZED CONDITIONS FOR STABILITY IN TENSION TESTS

In this paper an analysis of instability in tension tests is presented. It is assumed that the flow stress is a unique function of strain, strain-rate and temperature. For such a type of constitutive equation the three following cases have been analysed. First, when the temperature of a specimen is maintained constant, i.e. an isothermal process; for this case the relationship between uniform elongation, temperature and strain-rate has been obtained. The second case is related to instability under adiabatic conditions; this case has been numerically investigated for copper and aluminium. Finally, in the third case, the critical impact velocity in tension tests is discussed and some theoretical predictions are compared with experimental results. © 1968.