Computational models for impact mechanics and related protective materials and structures

The mechanics of impacts is not yet well understood due to the complexity of materials behaviour under extreme stress and strain conditions and is thus of challenge for fundamental research, as well as relevant in several areas of applied sciences and engineering. The involved complex contact and strain-rate dependent phenomena include geometrical and materials non-linearities, such as wave and fracture propagation, plasticity, buckling, and friction. The theoretical description of such non-linearities has reached a level of advance maturity only singularly, but when coupled -due to the severe mathematical complexity- remains limited. Moreover, related experimental tests are difficult and expensive, and usually not able to quantify and discriminate between the phenomena involved. In this scenario, computational simulation emerges as a fundamental and complementary tool for the investigation of such otherwise intractable problems. The aim of this PhD research was the development and use of computational models to investigate the behaviour of materials and structures undergoing simultaneously extreme contact stresses and strain-rates, and at different size and time scales. We focused on basic concepts not yet understood, studying both engineering and bio-inspired solutions. In particular, the developed models were applied to the analysis and optimization of macroscopic composite and of 2D-materials-based multilayer armours, to the buckling-governed behaviour of aerographite tetrapods and of the related networks, and to the crushing behaviour under compression of modified honeycomb structures. As validation of the used approaches, numerical-experimental-analytical comparisons are also proposed for each case.