Effects of spatially and temporally varied heat generation on fusion behaviors of thermoplastic composites under local thermal non-equilibrium conditions

Abstract

When thermally processing fiber reinforced thermoplastic (FRTP) composites, external fields are usually applied to generate spatially and temporally varied heat sources within composites, leading to complex local thermal non-equilibrium (LTNE) phenomena. To address this issue, a Lattice Boltzmann model is established to simulate the fusion behavior of FRTP composites at the scale of the representative elementary volume. The results show that LTNE effects on the fusion of FRTP composites are significant, especially when material has the low interfacial heat transfer coefficient. The increases in internal heat source power and matrix fraction can significantly accelerate melting rates, especially when considering LTNE effects. As compared to the situation where all parameters are at their minimum, the height of the melting region can be 15 times higher, and the height-to-width ratio of the melting region usually increases by 2–3 times. When fiber thermal conductivity increases, fusion and LTNE effects first increase and then weaken. When matrix fraction is low, increasing matrix fraction can increase temperature difference; but when it is high, it shows the opposite effect. This study provides a theoretical basis for the selection of thermal processing parameters of FRTP composites.