Research On Electrohydraulic Forming Process Of Local Deep Concave Characteristics Of AA5052 Aluminum Alloy

Lightweight body is one of the inevitable trends in the development of today’s automobile industry.Lightweight alloys such as aluminum alloys and magnesium alloys are increasingly applied to automobile bodies,which greatly reduces the body weight and achieves the goal of energy saving and emission reduction.However,in the room temperature forming environment,these light alloys exhibit poor formability,which largely hinders their promotion and application in vehicle bodies.Electrohydraulic forming technology is a kind of high-rate forming technology,which can improve the room temperature forming limit of forming sheet and realize room temperature forming of parts.Based on electrohydraulic forming technology,this paper takes O state AA5052 aluminum alloy plate as the research object,from the aspects of numerical simulation,process test,response surface optimization,etc.,to explore the forming process of local deep concave feature parts.Firstly,the simulation model of electrohydraulic forming and quasi-static electrohydraulic composite forming is established by using the commercial finite element software LS-DYNA,and the stress and deformation process of the sheet during single-step electrohydraulic forming and quasi-static electrohydraulic composite forming are explored..It is found that the deformation process of the two forming processes is that the center position is first deformed by force,and then the surrounding materials are driven to mold.Compared with the single-step electrohydraulic forming,the quasi-static electrohydraulic composite forming has more uniform stress and strain distribution of the sheet during the forming process,and the degree of rebound of the sheet hitting the die is lower.Secondly,the experiments of single-step electrohydraulic forming,two-step electrohydraulic forming and quasi-static electrohydraulic composite forming are designed and carried out.Taking the mold fitting and thickness distribution of the formed parts as the evaluation indicators,the advantages and disadvantages of different forming process schemes are compared,and the influence of the relevant process parameter settings in the forming process on these two evaluation indicators is compared.Through comparative analysis,it is found that the contour of the parts obtained by the two-step forming process is better than that of the single-step forming;the parts obtained by the quasi-static electrohydraulic composite forming process are better than other processes in terms of thickness reduction.At the same time,the thickness distribution and contour of the parts are obtained by comparing the test and numerical simulation,which verifies the accuracy of the simulation model.Finally,numerical simulation combined with response surface optimization method was used to explore the influence of two process parameters,discharge voltage and punching depth,on the modulus and maximum thickness reduction rate of the static electrohydraulic composite forming process.At the same time,a parameter scheme suitable for process forming is obtained through optimization.Using the method of response surface analysis,the variation law of the sticking modulus and the maximum thickness reduction rate of the formed parts with the discharge voltage and the punching depth was explored.The optimal discharge voltage obtained by optimization is 3.8k V,and the punching depth is 16.7mm.Through experimental verification,it is found that the maximum thickness reduction rate is basically consistent with the predicted value.It shows that the method has certain accuracy and reliability in optimizing process parameters to guide production.