Numerical Predictions Of Tensile Splitting Taylor Projectile And Dynamic Mechanical Property Of Q460D Steel

The Q460 steel,as high-strength steel for building structures,is often used in large landmark buildings such as Bird's Nest.Due to the demand for structural engineering for shock and explosion,investigating the dynamic behaviour of this material has become an urgent necessity.In this study,the mechanical properties of the Q460 D steel at different temperatures,strain rate and strain condition were investigated,and the modified Johnson-Cook constitutive relation and fracture criterion were calibrated.Based on the study of the shear and plane strain state,the Lode correlation of the Q460 D steel fracture was studied,and the Lode-related EJMA fracture criterion was applied and calibrated.After that,the Taylor impact test and numerical simulation were completed to analyse the influence of introducing Lode angle on the Taylor projectile failure prediction.Finally,based on the Taylor impact test,the influence of the material performance characterisation on the prediction accuracy of the Taylor impact test numerical simulation was analysed.The research outline of this paper is as follows:1.Material mechanical property test and parameter calibrationBased on the series material tests conducted at different temperatures,strain rate and strain condition,the calibration of nine parameters of the modified Johnson-Cook constitutive relation and six parameters of the fracture criterion were completed.Combined with the study of shear and plane strain tests,the Lode correlation of Q460 D steel fracture was studied,and three parameters of the Lode-related EJMA fracture criterion were calibrated,while the strain rate and temperature terms were maintained the modified Johnson-Cook fracture criterion.2.Taylor Impact Test and Numerical Simulation ResearchThe impact test of Q460 D steel Taylor projectile on a rigid target plate was carried out by using a one-stage light-gas gun system,and the failure mode of the projectile at different speeds was obtained.After that,combined with numerical simulation,the influence of the Lode angle on the failure prediction of Q460 D steel Taylor projectile was analysed and verified the validity of the material model parameter calibration.3.Analysis of the factors affecting the prediction accuracy of the Taylor impact testThrough the Hill48 yield criterion was calibrated based on Q460 D steel in-plane tensile tests at 0°,45° and 90°,the yield stage was reasonably characterised based on table method,and analysis was conducted based on the strain-rate sensitive coefficient as well as the plastic mechanism transformation under high strain rate,the influence of anisotropy,yield platform and strain-rate sensitivity to the numerical simulation on the Taylor impact test was studied.