A modified Johnson–Cook model and a novel Wilkins–Kamoulakos model used to simulate the impact between aero-engine turbine casing and fractured blade

The plastic deformation and fracture behavior of Inconel 718 play an important role in investigating the dynamic responses under impact loading. In this study, a plasticity and ductile fracture model is proposed, which explicitly accounts for the dependencies on stress state, strain rate and temperature. A Lode parameter is introduced into the JC (Johnson–Cook) plasticity model to describe the plastic flow of the material, while a novel WK (Wilkins–Kamoulakos) fracture criterion incorporates strain-rate and temperature dependencies. Quasi-static tests and dynamic tests at varying strain rate and temperature are conducted on Inconel 718, the material used for aero-engine turbine casing. The calibration of model parameters is taken from the numerical simulation of each test with an iterative inverse method. It is found that the plasticity of Inconel 718 superalloy has low sensitivity to stress triaxiality, while the influence of the Lode parameter is significant. The calibrated models are numerically implemented with the method of finite elements, and validated against high temperature ballistic impact tests between half-ring casing and blade. Good agreement between simulated and experimental results for plastic deformation and ductile fracture mode of the casing confirms the effectiveness of the developed modified JC (MJC) model and novel WK (NWK) failure criterion in practical applications.