Research On Measurement Of Elastoplastic Parameters And Deep Drawing Of Sheet Metal

Generally,metal materials are regarded as homogeneous materials in a macroscopic view.In fact,metal plates are polycrystals composed of a large number of small crystal grains,which makes the metal materials behave anisotropically.The degree of anisotropy of metal polycrystals depends on the crystal grains themselves and the orientation distribution of the crystal grains.The Hosford yield function can describe the yield and plastic deformation of sheet metal well,but its requirements for the direction of principal stress have limitations.It is only applicable when the three principal stress directions are consistent with the direction of the orthogonal symmetry axis of sheet metal.Therefore,this paper introduces texture coefficients into the Hosford yield function,and established the generalized Hosford yield function.Not only can it truly describe the yield and plastic deformation of sheet metal,but it is also suitable for any stress state.In this paper,the relationship between the elastic constant of the sheet metal and the texture coefficient of the sheet metal is given through the elastic constitutive structure of the metal sheet including the grain orientation distribution effect.Through the derived generalized Hosford yield function,the relationship between the plastic parameters in the yield function and the texture coefficient of the sheet is given.Based on this,the correlation between the elastic and plastic parameters of the sheet metal is found,and the calculation expressions that can determine all the elastic and plastic parameters of the sheet metal can be determined only by uniaxial tensile test data.A one-way tensile test was performed on aluminum and steel plates on the 100 k N electronic universal material testing machine Zwick-Z100,and all the elastic and plastic parameter values of the aluminum and steel plates were obtained by calculation.The Hosford yield function exponential parameter takes different values to form different Hosford yield functions,which fit the yield and deformation of different metal materials well.However,for different metal materials,the solution of the exponential parameter in the Hosford yield function has been a major focus and difficulty.The exponential parameter values calculated through uniaxial tensile experiments of aluminum and steel plates have a large dispersion.In this paper,the deep drawing cup forming experiment is used to find the one-to-one correspondence between the cup height of the drawing cup and the exponential parameter value,and the method of calculating the exponential parameter value through the drawing cup experiment is obtained.The cup drawing experiment was carried out on the 0.8mm thick 5052 aluminum alloy.Through the cup height measurement,the aluminum alloy exponential parameter value was calculated.Dynaform finite element software was used to simulate the process of aluminum sheet deep drawing cup.In the process of finite element simulation,it is ensured that the finite element yield function and material parameters are consistent with the actual aluminum sheet drawing experiment,and the calculated exponential parameter value is taken as a known finite element simulation of the drawing cup.The finite element software simulation cup height is compared with the experimental cup height to verify the feasibility of the method of calculating the exponential parameter value through the deep drawing cup experiment,and the result is good.The influence of different yield functions on the simulation results of drawing cups is analyzed by Dynaform,and the finite element calculation of the q value of the metal sheet is carried out.