Heat build-up of semi-crystalline polymers under monotonic loading : effects of stress triaxiality ratio
Résumé
The conversion of plastic work into dissipative heat, leading to an adiabatic heat build-up, is a well-known phenomenon. In polymers, the heat build-up depends on the strain rate [1], on the maximum strain [2] and, obviously, on the geometry of the test sample [3]. Even though the ambient testing temperature is lower than the glass transition temperature Tg, the temperature in the vicinity of a crack tip due to heat build-up may be exceptionally high so that it can locally reach Tg. A significant alteration of the local material response and damage mechanisms is then induced.
In the present study, a thermo-mechanical constitutive model, integrating temperature-dependent coefficients, has been developed. Predictive capabilities of the proposed thermo-mechanical model to simulate the isothermal behaviour of PolyAmide 11 (PA11) have led to adiabatic simulations, to account for the heat build-up highlighted experimentally, of ductile crack extension. The model parameters were identified using experimental data obtained from PA11 samples with a given stress triaxiality ratio. Predicted evolutions given by the proposed constitutive model for other stress triaxiality ratios will be discussed.
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