| With the advancement and development of the modern automobile industry,people’s requirements for automobile energy consumption are becoming more and more strict,and the lightweight of automobiles has become the development trend of the current automobile manufacturing industry.Pipe hydroforming technology is one of the most popular unconventional metal plastic forming technologies.Compared with stamping,casting and forging,this technology can produce lightweight and complex parts with high strength and low cost.One of the effective ways.In recent years,hydroforming technology has been widely used in aviation,ships,automobiles and other fields.The internal high pressure forming is a process in which the tube blank is placed in a cavity of a predetermined shape,and then the inside of the tube blank is filled with a high-pressure liquid,and the tube blank is formed under the pressure of the liquid,and the essence is the result of the coupling of the fluid and the solid.The numerical simulation of the internal high pressure forming process by the fluid-solid coupling method can more accurately reflect the change process of the fluid and solid in the internal high pressure forming.In this paper,the automotive torsion beam is taken as the research object,and the finite element simulation analysis of the internal high pressure forming process is carried out by the fluid-solid coupling method.Firstly,an internal high-pressure forming experiment of a rectangular tube was carried out by designing and constructing an internal high-pressure forming system of a simple rectangular tube.According to the internal high pressure forming experiment of rectangular tube,a finite element simulation model of high pressure forming in rectangular tube based on fluid-solid coupling method is established.The comparison between the experimental results and the simulation results verifies the correctness of the fluid-solid coupling numerical simulation method and the feasibility of the fluid-solid coupling method for the finite element analysis of the internal high pressure forming.Based on this,the finite element simulation model of the high pressure forming of the torsion beam is established based on the fluid-solid coupling method.The sliding mold suitable for the torsion beam is designed for numerical simulation.The key factors such as the shaping pressure,loading path and friction coefficient are studied.The effect of forming quality.The results show that the internal hydraulic pressure rises alternately in the process of torsion beam hydraulic bulging,and the overall change trend is linear.With the increase of liquid pressure,the wall thickness of torsion beam shows a thinning trend,and its maximum thinning rate is located at the transition point of rounded corners and straight edges on the "stepped" shaped area.When the liquid pressure exceeds 180 MPa,the torsion beam has been basically coated with film,and its wall thickness distribution and radius of rounded corners no longer change.With the increase of axial feed speed,the wall thickness of the end of torsion beam and "ladder" shaped zone decreases,while the wall thickness of the transition zone and "V" shaped zone basically does not change.That is to say,the amount of axial feed mainly concentrates on the end of torsion beam and "ladder" shaped zone.With the increase of friction coefficient,the uniformity of wall thickness distribution of torsion beam decreases,and the friction coefficient has the greatest influence on the v-shaped zone.In the end,the best forming results were obtained under the condition of shaping pressure of 180 MPa,friction coefficient of 0.12,axial feed speed of 150mm/s and loading time of 0.16 s.The minimum wall thickness was located at the transition point between the rounded corners and straight edges in the "stepped" shaped area.The minimum wall thickness was 3.12 mm and the thinning rate was 10.86%,which met the requirements of engineering application. |
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