In order to effectively predict the fracture of AA7075-T6 sheet, the forming limit curves of AA7075-T6 high-strength sheet were drawn according to Morciniak Kuczyski (M K) model and Lou Huh criterion, respectively. Th...In order to effectively predict the fracture of AA7075-T6 sheet, the forming limit curves of AA7075-T6 high-strength sheet were drawn according to Morciniak Kuczyski (M K) model and Lou Huh criterion, respectively. The errors between the predicted values of the two theoretical prediction models and experimental values were calculated by error analysis. The forming limit curves were verified by the punch stretch test to evaluate the prediction accuracy of M K model and Lou Huh criterion. The error analysis results show that the mean error of Lou Huh criterion with the optimal parameters for all tensile specimens is 25.04%, while the mean error of M K model for all tensile specimens is 74.24%. The prediction accuracy of Lou Huh criterion in predicting the fracture of AA7075-T6 sheet is higher. The punch stretch test results show that the forming limit curve drawn by Lou Huh criterion can effectively predict the fracture of AA7075-T6 sheet, but the prediction accuracy of M K model is relatively poor.展开更多
Marciniack–Kuczinski(M–K)model is widely used to predict material's forming limit curve(FLC).The prediction of FLC traditionally neglected through-thickness normal stress.However,it cannot be neglected in some f...Marciniack–Kuczinski(M–K)model is widely used to predict material's forming limit curve(FLC).The prediction of FLC traditionally neglected through-thickness normal stress.However,it cannot be neglected in some forming processes.Much work has been done to study the effect of through-thickness normal stress on FLC with constant through-thickness normal stress or constant ratio of through-thickness normal stress and maximum principal stress.In addition,based on Nakazima test process,the ratio of through-thickness normal stress and maximum principal stress has been derived,which was a function of instantaneous thickness and loading path.Here,initial groove angle in M–K model was not considered.In this paper,uniaxial tension tests and Nakazima tests were performed on 7B04 aluminum alloy.Based on Hill 48 yield criterion and M–K model,the prediction model of FLC was established.The increase of thickness can enhance FLC.Meanwhile,it is necessary to consider through-thickness normal stress and initial groove angle in prediction model.On the left side of FLC,the effect of initial groove angle on FLC is weakened by increasing sheet thickness.On the right side of FLC,the effect of initial groove angle on FLC is strengthened by increasing sheet thickness.On the right side of FLC,the relation between limit strain points with different thicknesses is linear under one certain loading path.Thickness has decisive effect on through-thickness normal stress level and the changing trendy of through-thickness normal stress during calculation is different under different stress condition.展开更多
基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究。通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热...基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究。通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数。V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体。与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据。展开更多
基金Project (51775481) supported by the National Natural Science Foundation of ChinaProject (E2019203418) supported by the Natural Science Foundation of Hebei Province, ChinaProject (ZD2017078) supported by the Science and Technology Plan of Hebei Higher School of Education Department, China。
文摘In order to effectively predict the fracture of AA7075-T6 sheet, the forming limit curves of AA7075-T6 high-strength sheet were drawn according to Morciniak Kuczyski (M K) model and Lou Huh criterion, respectively. The errors between the predicted values of the two theoretical prediction models and experimental values were calculated by error analysis. The forming limit curves were verified by the punch stretch test to evaluate the prediction accuracy of M K model and Lou Huh criterion. The error analysis results show that the mean error of Lou Huh criterion with the optimal parameters for all tensile specimens is 25.04%, while the mean error of M K model for all tensile specimens is 74.24%. The prediction accuracy of Lou Huh criterion in predicting the fracture of AA7075-T6 sheet is higher. The punch stretch test results show that the forming limit curve drawn by Lou Huh criterion can effectively predict the fracture of AA7075-T6 sheet, but the prediction accuracy of M K model is relatively poor.
基金the support from the National Natural Science Foundation of China(51575028)the Fundamental Research Funds for the Central Universities(YWF-18-BJ-J-75)。
文摘Marciniack–Kuczinski(M–K)model is widely used to predict material's forming limit curve(FLC).The prediction of FLC traditionally neglected through-thickness normal stress.However,it cannot be neglected in some forming processes.Much work has been done to study the effect of through-thickness normal stress on FLC with constant through-thickness normal stress or constant ratio of through-thickness normal stress and maximum principal stress.In addition,based on Nakazima test process,the ratio of through-thickness normal stress and maximum principal stress has been derived,which was a function of instantaneous thickness and loading path.Here,initial groove angle in M–K model was not considered.In this paper,uniaxial tension tests and Nakazima tests were performed on 7B04 aluminum alloy.Based on Hill 48 yield criterion and M–K model,the prediction model of FLC was established.The increase of thickness can enhance FLC.Meanwhile,it is necessary to consider through-thickness normal stress and initial groove angle in prediction model.On the left side of FLC,the effect of initial groove angle on FLC is weakened by increasing sheet thickness.On the right side of FLC,the effect of initial groove angle on FLC is strengthened by increasing sheet thickness.On the right side of FLC,the relation between limit strain points with different thicknesses is linear under one certain loading path.Thickness has decisive effect on through-thickness normal stress level and the changing trendy of through-thickness normal stress during calculation is different under different stress condition.
文摘基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究。通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数。V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体。与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据。
基金supported by the National Natural Science Foundation of China (No.51975330)Key Research and Development Program of Shandong Province,China (No.2021ZLGX01)Project of Colleges and Universities Innovation Team of Jinan City,China (No.2021GXRC030)。
