Executive Summary : | Amorphous glassy polymers have important engineering applications in defence, aerospace, and other sectors. An accurate prediction of deformation and fracture can facilitate the reliable design of components. Damage models are essential tools for numerical simulation of fracture. The fracture of amorphous polymers depends on loading rates, thermo-mechanical effects, and triaxiality. A damage model should consider all these factors. Such a detailed damage model is not available in the literature. The development of damage models requires an understanding of fracture mechanisms at the micro or nanoscopic level. It is a well-established fact that the crazing leads to failure in amorphous polymers. For relatively ductile polymers like Polycarbonate (PC), crazing is preceded by nucleation, growth, and coalescence of multiple microscopic voids. Thus, understanding microscopic void growth and the influence of triaxiality, thermo-mechanical effects, and loading rate on the void growth mechanism in polymers is important for developing damage models. For metals, void growth analysis is a well-established methodology to develop or enhance the capability of existing damage models. However, for polymers, void growth studies are very limited, and further effects of important parameters mentioned above are completely missing from the literature. The objective of the current proposal is to study the influence of loading rate and thermo-mechanical effects on void growth in amorphous polymers through numerical simulations. The growth of a microscopic void will be studied under a range of triaxiality to simulate various loading conditions. An appropriate thermo-mechanical elastic-viscoplastic constitutive model for amorphous polymers will be used. The model covers essential features of deformation in polymers, such as rate-dependent, temperature-dependent, and pressure-dependent yield, softening, and hardening. Further, the results of void growth analysis will be used to modify an existing damage model to account for rate and thermo-mechanical effects. The damage model will be useful in the reliable design of engineering components. |