The Forming Limit Of Sheet Metal Under Different Loading Paths

Sheet metal forming performance has been a research focus in the field of metal plastic forming.Sheet metal plastic forming application range is very wide,has a great influence on production and life,such as aerospace,automobile manufacturing industry,metal processing field and so on.Because of the new material,new parts forming technology,the new metal craft processing technology constantly emerging,various fields on the properties of material demand is higher and higher,both to ensure the strength of the sheet metal,and to ensure that the materials of lightweight,so the research on sheet metal plastic forming is particularly important.Sheet metal forming limit is reflect the degree of plastic deformation in the process of maximum deformation performance index,so the research on the properties of metal materials forming gradually turned into focus on the study of material forming limit.The forming limit diagram is the most direct and most effective in the study of forming limit,the most widely used form of expression,it can be comprehensive and concise response of different strain paths were material forming performance.So at this stage how to more accurately predict the forming limit diagram has become one of research hot spots.The research methods of forming limit is not perfect enough,research method is experimental method,theoretical prediction method and the method of numerical simulation.This project uses experimental method,theoretical method respectively for material LF2,material AA5182,material DP600 and TRIP780 forming limit analysis.Through uniaxial tensile tests of material xx and get the material mechanics performance parameters.According to the obtained parameters calculate the material of different constitutive equation model,and calculate the materials needed for the parameters of the yield criterion.After the materials for biaxial tensile experiment,Get the materials forming limit experimental data under different loading paths.Through the experiment to obtain the data to prepare for subsequent theoretical predictions.Application of new shear failure criterion and the M-K criterion,using MATLAB software,under the Swif?Voce and Hockett constitutive equations model,based on Hill48?Gotoh?Barlat89?Mises yield criterion to calculate the forming limit diagram for the material LF2,AA5182,DP600and TRIP780.By comparing the difference between theoretical prediction results and test data to a concrete analysis of different constitutive equation and the influence of the yield criterion of forming limit,and verify the new shear failure criterion and the M-K criterion for the applicability and the accuracy of different materials.On the basis of the new shear failure criterion,the accuracy of the new instability criterion is verified.Finally,accurate prediction of sheet forming limit is achieved.