双尺度SiCp/A356复合材料的热变形行为及本构模型

Hot deformation behavior and constitutive model of dual-scale SiCp/A356 composites

利用Gleeble-1500D热模拟试验机研究了双尺度SiCp/A356复合材料在温度460~520℃、应变速率0.01~5 s^-1条件下的热变形行为。根据试验数据绘制出双尺度SiCp/A356复合材料真应力-真应变曲线,并在传统Arrhenius型双曲正弦函数方程基础上引入应变量构建了基于应变补偿的本构模型,同时构建了基于BP神经网络的本构关系模型。结果表明:双尺度SiCp/A356复合材料真应力-真应变曲线具有典型的动态再结晶特征,流变应力随变形温度的降低或应变速率的升高而增加;在真应变为0.4的条件下,热变形激活能为468.32 kJ/mol;通过应变补偿本构模型和BP神经网络本构模型得到的流变应力的预测值与试验值之间的相关系数R分别为0.975和0.998,平均相对误差分别为2.97%和0.92%;对比发现该BP神经网络本构模型具有更高的预测精度,能够更加准确预测双尺度SiCp/A356复合材料高温流变应力。

Hot deformation behavior of dual-scale SiCp/A356 composites under the conditions of deformation temperature of 460-520℃and strain rate of 0.01-5 s^-1 was investigated by using a Gleeble-1500 D thermal simulation testing machine.The true stress-true strain curves of the double-scale SiCp/A356 composites were drawn according to the test data.The constitutive model based on strain compensation was constructed by introducing strain variables based on the traditional Arrhenius hyperbolic sine function equation,and the constitutive model based on BP neural network was constructed.The results show that the true stress-true strain curves of the double-scale SiCp/A356 composites has typical dynamic recrystallization characteristics,and the flow stress increases with the decrease of deformation temperature or the increase of strain rate.The activation energy of thermal deformation is 468.32 kJ/mol under the condition of true strain of 0.4.The correlation coefficients R between the predicted values of flow stress obtained by the strain compensation constitutive model and BP neural network constitutive model and the test values is 0.975 and 0.998,respectively,and the average relative error is 2.97%and 0.92%,respectively.The results show that the BP neural network constitutive model has higher prediction accuracy and can predict the high temperature flow stress of the double-scale SiCp/A356 composites more accurately.