Thermal-mechanical Coupled Analysis Of High Temperature Contact Friction On Rough Surface Based On ANSYS

With the development of automobile lightweight,the ultra-high strength steel sheet formed by hot stamping process has been widely used.Compared with the traditional cold stamping technology,hot stamping technology at high temperature,the plasticity of the material is enhanced,forming ability is good,capable of forming complex stamping parts at one time.It can obviously reduce the springback in cold stamping forming,the precision of the parts is high and the forming quality can be guaranteed.However,there are still many problems to be solved in the hot forming process at present,such as slight rebound and local wrinkle at the bending part,severe damage on the metal surface and uneven distribution of metal structure caused by hot forming.Based on the numerical simulation method,a finite element model of the contact friction on rough surface is built.The thermo mechanical coupling analysis of the contact down pressure and sliding process is carried out to explore the microscopic friction and wear mechanism of the high-temperature friction interface.In this paper,a random rough surface is constructed by MATLAB and ANSYS,and the finite element model of hot forming contact friction is established by using the APDL parameterized design language.The three-dimensional transient thermomechanical analysis is carried out by changing the roughness,temperature and the size of the external load.The changes of contact interface pressure,rough solid Mises stress,smooth solid temperature and real contact area of contact interface in contact pressure process are studied.The contact interface pressure,the rough solid Mises stress,the real contact area and the change of the tribological properties at high temperature contact are also studied in this paper.The results show that contact pressure,under high temperature condition,rough solid Mises stress and real contact area are mainly distributed near the micro convex peak of rough solid,and increase with the increase of external pressure during the down pressing process.There is a steady fluctuation in the sliding process,and the overall numerical size is directly related to the temperature and load applied..Under the same condition,the higher the temperature,the lower the roughness,the greater the real contact area ratio,and the smaller the Von Mises stress of the rough solid and the maximum contact pressure of the contact interface nodes.When the contact state is changed from the adhesive contact to the sliding contact,the contact pressure decreases sharply in a short time,while the maximum Von Mises stress increases rapidly,and the real contact area will continue to increase.The amount of plastic deformation is proportional to the action pressure,and the plastic strain is further increased under the action of tangential friction in the initial stage of change of contact state.The maximum Von Mises stress is distributed on the subsurface during the contact friction and sliding process,which reveals the cause of the failure of the material.In the initial contact of the rough surface,the micro convex peak slips relative to the contact surface,and it is in the bond contact state with the increase of the external load.The vibration law of rough solid under different working conditions is approximately the same,the higher the temperature,the greater the load and the smaller the vibration amplitude in the sliding stage.That is,the more smooth the sliding state is.In this paper,the mechanism of the sliding friction of micro high temperature and rough contact is studied by the finite element method,the conclusions can provide some theoretical guidance for the optimization of hot forming process at high temperature.