Application of cavity expansion analysis to penetration problems

Cavity expansion analysis (CEA) presents a general framework for characterizing the penetration resistance of target materials. This dissertation extends the CEA in three different areas: (a) analysis of ductile targets accounting for finite boundaries and finite ductility; (b) analysis of brittle ceramics considering the cracking and comminution behavior; (c) development of a new penetration model for metals to overcome limitations of the existing models.; The existing cavity expansion theory for ductile materials was applied to characterize punch tests performed on PMMA. Both the punching force and the size of plastic zone developed, were well explained by the cavity expansion analysis. The existing analyses for metals consider cavity expansion in a infinite material possessing infinite ductility. In this dissertation, CEA is modified to account for a finite boundary and to incorporate the effects of finite ductility of metallic targets, which develop tensile cracks. The results of the analyses are shown to be in good agreement with test data.; Recently, brittle ceramics like Al{dollar}sb2{dollar}O{dollar}sb3{dollar}, AlN have been investigated as potential armor materials. They possess compressive strength properties that are superior to those of metals. CEA have been performed for brittle materials with various constitutive assumptions. These results do not always agree with experimental penetration resistance values. In this research, a constitutive behavior based on the current understanding of the brittle behavior is used to derive quasi-static and dynamic cavity expansion pressures. Important material parameters that affect the penetration resistance are identified. The cavity expansion pressure derived in this analysis is in excellent agreement with experimental penetration resistance values.; The existing penetration models do not always agree with the experimental penetration behavior of eroding rod projectiles at different velocities. A new approach is hypothesized to model the penetration in ductile targets. In addition to the elastic and plastic zones, a "damaged zone" zone is recognized in the target. In comparison to the existing models, the new approach shows superior agreement with experimental data, both for low and high velocities.