Implementation of Potential Function to Investigate Fracture Simulation in Brittle Materials

Abstract

The advent of new materials especially nanomaterials, biomaterials, composites have posed immense challenges in research community to completely understand the fracture mechanism, this is because of complexity in architecture of unit cells at microstructure level, hetrogenity, intircate surfaces, mixed loading. There are different approaches to simulate fracture mechanism such as molecular dynamics, cohesive zone modelling, continuum mechanics, and extended finite element method, but these methods have some pros and cons. The VIB method is more advantaegous than other methods, in this method, the domain is presumed to be consisting of material points which are randomly distributed and connected through virtual bond, the stress-strain response is controlled through bond density function. Strain energy density at continuum level is equated with potential energy stored within the bond via. cauchy born rule, these stress-strain expressions are further coded in Fortran and implemented in ABAQUS using user subroutine VUMAT. Uniaxial tensile test simulations are performed to calibrate VIB model parameters with known mechanical properties which are determined from experiments. In order to prove the robustness of the code several standard cases of fracture plate with a hole and plate with a crack problem are solved. Then MVIB formulations extended for the composite materials. The analysis of progressive damage failure in composite (carbon, epoxy) is examined. Further, reinforced composite model is tested at different loading conditions such as uniaxial, biaxial, shear case etc. The MVIB model is applied to study debonding phenomena of Z pins in mode I loading condition. The crack initiation and propagation in case of a plate with a hole problem, simulations results agree reasonably with a data published in literature. In the reinforced composite material crack propagate in the edge of the carbon and extends in the matrix material. Delamination strength was increased by inserting of Z pins in the double cantilever beam