Fracture Simulation of Structural Glass by Element Deletion in Explicit FEM

Abstract

In finite element simulation of glass cracking for practical engineering problems, the method of element deletion is often used despite its shortcomings. With this technique, an element is removed from the system upon reaching a certain failure criterion. Many different formulations for the failure behaviour of an element are possible, differentiated by the physical correctness of their representation and by their implications on the numerical stability of the calculation. In this paper, three failure models are characterised by use of a unit element model and evaluated for the drop weight impact on a monolithic glass plate. Several issues can be identified: (i) incorrect calculation of fracture energy for large-sized elements; (ii) shock wave propagation upon deletion of an element leading to spurious failure of other elements; (iii) unrealistic crack formation when the failure model does not account for crack directionality. A crack delay failure model for structural glass is proposed to avoid the aforementioned problems. This failure model uses only physical material properties as input and limits the damage rate during fracture.