Numerical Simulation Of The Failure Of Ceramics Under Compressive Loading

A lattice spring model which based on Gusev's finite element parameter mapping is used to simulate the failure of polycrystalline alumina(Al2O3)under compressive loading.This method has the advantage that in theorythe calculated node displacements are the same as those calculated by FEM.The concepts in this method are clear and simple,we can handle cracking easily.An elastic-brittle model is used and the fracture criterion is based on the Griffith's energy principle.Grain boundaries are considered,which will affect crack propagation.Simulations of alumina with a certain porosity under impact loading are carried out,the peak strengths,which represent the strengths of the material under compressive loading,agree well with the experimental data.We investigated the responses and the strain rate sensitivities of porous and non-porous specimens,and found that porous specimen has strain rate sensitivity while non-porous specimen does not,in addition,the former's time-history curve of crack density has distinct steps while the latter's does not.Further analysis shows that there are two crack arrest mechanisms corresponding to these steps,which causes the apparent strain rate effect in porous ceramics.We investigated the influence of voids on the material's Young's modulus which decreases as the porosity increases.The void's shape also has significant influence on Young's modulus,in general,the more slits in the specimen,the lower Young's modulus the specimen gains.Simulations of failure waves in a glass rod impacting a rigid wall are carried out,the results agree well with experimental phenomena which show that the glass rod breaks in ways of failure waves and spalling.