Material model characterization of a Ti/SiC metal matrix nanocomposite coating subjected to hypervelocity impact

Titanium alloys have been extensively used in the aerospace industry because of their outstanding properties, such as high strength-to-weight ratios, high corrosion resistances, and high melting points. However, it is hypothesized that the performance of titanium alloys can be further enhanced to be more resistant to hypervelocity impact by coating them. Earlier experimental investigations showed that coating a Ti-6Al-4V substrate by Ti/SiC Metal Matrix Nanocomposite (MMNC) improved hypervelocity impact resistance of the composite. The coating had 7% SiC by volume. These experiments were simulated using the Smoothed Particle Hydrodynamics (SPH) modeling approach. Johnson-Cook material models were used for the Ti-6Al-4V substrate and the Lexan projectile. Due to the lack of detailed mechanical characterization of the MMNC, a bilinear elastic plastic material model was used to model the coating. In this study, single-parameter sensitivity analyses were conducted to understand the sensitivity of the SPH model based on comparison with the experimental crater volume. The parameters of the bilinear elastic plastic material model were modulus of elasticity, Poisson's ratio, yield strength, tangent modulus, and the failure strain. These parameters were varied by ±5%, and ±10% of their respective base values for a Ti/SiC Metal Matrix Nanocomposite (MMNC) with 35% SiC by volume for which stress-strain curves under various strain rates were available. These values were applied to the full range of tested velocities. Exploiting the parameters from sensitivity analyses, the results show that the accuracy of SPH modeling of MMNC can be enhanced when experimental data is not available. The results also show that bilinear elastic plastic material model can be used for MMNC coating under elevated strain rates.