Research On 6061-T6 Aluminum Alloy Constitutive Model And Differential Temperature Hydroforming Of Spherical Bottom Tube

With the increasing attention to energy conservation and environmental protection,aluminum alloy materials are widely used because of their high strength and light weight.However,the forming of aluminum alloys at room temperature is limited by the disadvantages of low plasticity and difficulty in forming complex parts.Hydroforming technology is currently one of the effective ways to improve the forming quality.Differential temperature forming can use the soft.Hydroforming technology is currently one of the effective ways to improve the forming quality.Differential temperature forming can use the softening of aluminum alloy to improve plasticity,and the combination of the two can significantly improve the forming performance of aluminum alloy sheets.In this paper,6061-T6 aluminum alloy spherical-bottomed cylindrical parts are used as the research object,and the method of combining numerical simulation and experiment is used to study the differential temperature and Hydroforming process.In order to obtain accurate numerical simulation data,a constitutive model that can truly reflect the temperature deformation characteristics of 6061-T6 aluminum alloy material was established through a single hot tensile test and BP neural network modeling.The WDW-30 M electronic universal tensile testing machine was used to conduct hot tensile experiments on 6061-T6 aluminum alloy at different strain rates and different temperatures.Through the preprocessing of the data and the training of the data samples,a BP neural network model was constructed,and the temperature,strain,and strain.The rate ? ? is used as input,and the stress is used as output.By comparing the experimental data with the predicted data,the correlation fitting coefficient reached 0.9991,and the accuracy reached the required 0.001.Then embed its constitutive model into numerical simulation software.In this paper,ABAQUS finite element simulation software is used to simulate the forming of spherical bottom cylindrical parts under the conditions of liquid filling and differential temperature in parallel.In this paper,pre-expansion is added in the early stage of Hydroforming.The pre-expansion is used to advance the drawing to improve the uniformity of the wall thickness distribution of the part and reduce the maximum thinning rate.Numerical simulation under only liquid filling condition was carried out.By controlling the initial pre-expansion pressure and pre-expansion height,the wall thickness distribution analysis of the formed parts under different parameters obtained the optimal preexpansion pressure of 14 MPa and the optimal pre-expansion.Height 4mm.Under this condition,the pressure of the liquid chamber is used as a variable,and the wall thickness distribution of the formed part is analyzed by controlling the pressure of the liquid chamber.The optimal loading pressure of the liquid chamber is 35 MPa.On this basis,by controlling the different temperatures between the punch and the sheet material,the optimal temperature loading combination punch is 50?,and the sheet material and the female mold are200?.Finally,the optimal parameters are selected for the experiment,and the experimental results are consistent with the predictions of the numerical simulation results.