Optimization method of the material model parameters at hypervelocity impact

In the research of hypervelocity impact, it is very difficult to identify the metallic material's parameters on the condition of the extreme distortions and high strain rate. A method is provided to identify and optimize the material's strength model parameters. Johnson-Cook strength model and Gruneisen equation of state were selected to describe the characteristics of Al alloy under the hypervelocity impact. The SPH(Smooth Particle Hydrodynamic) algorithm and the Ls-dyna software are applied to simulate the hypervelocity impact between the Al-1100 projectiles and Al-6061 plates. There was much error between the results of simulation and experiment. In order to reduce the error, it is essential to modify the material's parameters. QSRSM(Quadratic Successive Response Surface Method) is applied to construct the approximate function. The residual sum-of-squares between the results of experiment and simulation is defined as the optimization objective. Latin Hypercube Sampling method is selected to do the design of experiment. Five parameters of Johnson-Cook strength model were determined as optimization variables. LS-OPT and Ls-dyna software are used to calculate the optimization model. Optimization results show that the simulation accuracy was better using the modified parameters than using the initial parameters compared to the results of experiment. The optimization method will be significant for identification of the materials' parameters for hypervelocity impact.