Development of a constitutive microdamage model for simulation of damage and fracture of metallic plates caused by hypervelocity impact.

摘要

A constitutive microdamage model is developed capable of simulating high shock compression, release, dilatation (tension), and microdamage evolution leading possibly to fracture and penetration of targets after hypervelocity impact. The microdamage constitutive model is applicable to polycrystalline metals and is appropriate in the lower range of hypervelocity impact velocity, i.e. approximately 2–7 Km/s, over which the projectile and target materials remain in the solid state. The model implements the Mie-Gruneisen equation of state coupled with the Hugoniot relations along with expressions of non-linear elastic moduli (bulk and shear) as functions of volume strain, temperature and microdamage. The viscoplastic material response includes strain and strain rate hardening and temperature and microdamage softening. The microdamage evolution model is based on the micromechanics of an expanding void, and is capable of modeling void compaction and expansion that leads to spall-fracture as an evolutionary time dependent process. The constitutive microdamage model was implemented in the Autodyn™ software and a series of computer simulations of hypervelocity impact experiments on Al₁₁₀₀ plates with soda-lime glass spherical projectiles were conducted. The results of the simulations are compared with the laboratory experimental results in terms of crater, penetration hole and back-wall spallation geometry of the target plate.