Q235B钢Johnson-Cook模型参数的确定

Determination of parameters of Johnson-Cook models of Q235B steel

使用万能材料试验机、扭转试验机和霍普金森拉杆装置研究了Q235B钢在常温~950℃的准静态、动态力学性能,获得了Q235B强度与等效塑性应变,应变率和温度的关系以及延性与应力三轴度,应变率和温度的关系。基于实验结果,修改了Johnson-Cook（J-C）强度模型中的应变强化项以及Johnson-Cook失效模型中的温度软化项,并结合数值仿真标定了相关模型参数。最后通过Taylor撞击试验验证了模型参数的有效性。

Strength and ductility data for Q235 B steel from 20 ℃ to 950 ℃ were obtained from tension tests with smooth cylindrical specimens （SCSs）.The strain rate sensitivity was studied by conducting split hopkinson tension bar （SHTB）tests and uniaxial tension tests of SCSs.The influence of stress triaxiality on ductility was revealed by conducting upsetting tests of cylinder specimens,tension tests of pre-notched cylinder specimens and torsion tests of SCSs.Slightly modified versions of two Johnson-Cook （J-C ） models describing flow stress and failure strain were presented to characterize the properties of Q235 B steel as a function of strain rate,temperature and stress triaxiality.The corresponding model parameters were calibrated based on the test data and with the help of finite element simulation.The validity of the model parameters was verified with Taylor impact tests.