Experimental And Simulation Study On Engine Beam Hydroforming Based On Fluid-solid Method

With the advantages of better forming rigidity,more light weight and high production efficiency,the hydroforming technology has a wide application prospect in automobile and aerospace industries.In fact,the hydroforming process is a typical fluid-solid coupling problem and the internal flow field has complex characteristics with the process of fluid-solid interaction.Fluid-solid coupling method has many advantages compared with the traditional analysis method which simulates the hydroforming process by equivalent uniform load acting on the inner wall of the pipe.Analysis of automobile engine beam hydroforming based on the fluid-solid coupling method can take the complex physical phenomenon like velocity fluctuation and pressure attenuation of the fluid into consideration,study the forming process under real working conditions,provide strong guidance for practical automotive engine beam hydroforming technology.In this paper,experiment combining with numerical simulation based on fluid-solid coupling method is used to analyze the hydroforming process of automobile engine beams.Firstly,a typical filling structure test system is designed and set up,and the correction of numerical calculation method and simulation programs are verified by comparing the experimental results with the simulation results.Then,the hydraulic bulging experiment of 20# steel rectangular cross-section pipe without axial feed and the numerical simulation based on fluid-solid coupling method are carried out respectively,the correction of the tube hydroforming simulation based on fluid-solid coupling method is verified through the contrast of experimental and simulation results,and the influences of key parameters on the results of hydroforming quality are analyzed.Based on this,the fluid-solid coupling finite element model of engine beam hydroforming is set up,the main process parameters are proposed,the hydroforming process of the beam is simulated,and the influence of different forming pressures,hydraulic loading times and loading paths on the forming quality are analized.The results show that,with the heighten of internal pressure,the thinning rate of the beam increases.When the pressure reaches 200 MPa,the beam has sticked the mould and the wall thickness no longer changes.With the extension of loading time,the thinning rate decreases,the thinning rate of section A reaches minimum of 21.027% under the circumstances that the loading time is 2.5s,as well as the best forming quality reached.Pressure increases slowly first then fast loading path is conducive to feed material during the yield period,so as,to improve the wall thickness uniformity,decrease the wall thickness thinning rate and improve the tube hydroforming quality.In this paper,method of experiment combining the simulation is taken,analysis of automobile engine beam hydroforming based on fluid-solid coupling method is completed,and a strong guidance for practical automotive engine beam internal high pressure forming technology is provided.