Multiscale Analysis of the Stress and Burst Speed of a Titanium Matrix Composite Ring Considering the Viscoplasticity of the Matrix

A multiscale model is developed for stress analysis and burst speed prediction of a titanium matrix composite (TMC) ring. The proposed multiscale model is based on finite-volume directly averaging micromechanics (FVDAM) to connect the TMC ring and the composite microstructure. Moreover, Bodner-Partom’s constitutive model is adopted to characterise the viscoplasticity of the titanium cladding and the matrix. The effects of viscoplasticity on the mechanical behaviour and burst speed of the TMC ring are presented and discussed for the first time via macromechanical and micromechanical analysis. The results suggest that considering the viscoplasticity of the titanium matrix and cladding leads to a decrease in the burst speed of the TMC ring, especially at elevated temperatures such as 315 ℃ and 482 ℃. Burst rupture of the TMC ring also occurs after a certain time in the load-holding stage at these elevated temperatures and a low, constant angular speed, even though no burst rupture is predicted in the loading stage. Hence, the newly defined load-holding burst speed, which is relative to the load-holding time, is predicted at elevated temperatures. The results of the load-holding burst speed provide more comprehensive information on the safety assessment of a TMC ring at elevated temperatures.