A viscoelastic-viscoplastic model of titanium structures subjected to thermo-chemo-mechanical environment

This manuscript provides a new coupled thermo-chemo-mechanical computational model for ti-tanium structures subjected to extreme loading and environment. The proposed model accounts for the formation of oxygen enriched (alpha-case) titanium, as well as the coupling effects between the response characteristics of mechanical and oxygen infiltration processes into titanium at high temper-ature environment. The formation of alpha-case at the surface of the structure is modeled as diffusion of oxygen into the titanium substrate. The mechanical response of the structure is idealized using the Johnson-Cook model, which is generalized to account for the effects of oxygen induced embrittlement and hardening. The interplay between mechanical damage, oxygen infiltration and temperature on the chemo-mechanical response is evaluated using numerical simulations. The fully coupled mechan-ical and diffusion processes are solved based on a staggered coupling algorithm. The capabilities of the computational model are assessed by the analysis of a panel composed of Ti-6Al-2Sn-4Zr-2Mo titanium alloy subjected to thermal shock loading