Mechanics and constitutive modeling of smart engineering materials accounting for visco-elasto-plastic-damageable behaviors

Smart asphaltic, cementitious and composite materials are drawing great attention in civil engineering and material science. The aim of smart material is to extend the lifespan and improve the mechanical performance of structures. These materials have in common complex behaviors like visco-elasticity, visco-plasticity, progressive damage and fracture. A good understanding of these phenomena is required to improve and extend the capabilities of smart materials. To do that, constitutive laws are needed to describe the non-linear mechanisms where the crucial parameters must be identified. The development of a mathematical and simulation framework is the key to predict and investigate new developments in smart materials. In this paper, a three-dimensional visco-elasto-plastic-damageable constitutive model is proposed, consisting of three basic modules: visco-elasticity, plasticity and damage, which can provide rate-dependency on stiffness and strength, and describe progressive degradation and failure. An efficient gradient-less optimization algorithm with user-defined constraints is developed to identify the material parameters. This methodology can solve a highly non-linear function with multiple variables, where the physical meaning and the effect of each variable are understood. The model and the optimization approach are implemented using the finite element code ABAQUS via user-defined material subroutines (V)UMAT. The proposed constitutive model is thoroughly validated and verified with experimental results. This numerical framework will allow for adding additional features like the effect of temperature on the mechanical properties and the self-healing capability in further research.