The Optimization Of The CCB Rack Weld And Its Numerical Simulation

With the increasingly competition in auto market, manufacturing cost of the vehicle is being more and more important, partial component weld is too long to reduce the cost .In this paper, according to overall length of the weld of the current cross car beam and the welding process, take the simulation and calculation of the temperature field of the beam with the ANSYS and HYPERMESH, residual stress field of the work piece as well as stress field of the synthesis, and optimize the beam weld on the base of simulation and experiment.The beam is divided into various small parts with the software of HYPERMESH, calculating each small part of them separately and taking the two tubes model as the research object. Calculation results of the temperature field of the cross beam pipes show that the pipe lap joints exist two peaks in the adjacent weld seam after using the intermittent welding method, namely, there is the phenomenon of cyclic heating. In the welding process of assembly, get the data of the interval time of seams and the temperature field distribution of the key beams which is coincidence with the calculation results.The calculation results of the distribution of residual stress fields on two pipes based on ANSYS indirect coupling calculation and measurement shows that, residual stress in the thickness direction is low, the result from the cross section between weld metal and base metal shows that the distribution of residual stress along the length direction of weld is constant, because of cycle heating and non-uniform heating on the two ends of the weld, which residual stress get an abrupt change. According to the requirement to optimize the weld seam of vehicle bracket, we design the tensile test of two pipes, simulate the operating stress in the practical work, and get the rupture force. Using linear calculation to couple working stress and residual stress on two pipes, it shows the same result compared to the tensile test. On the basis of simulative calculation, the weld quality evaluation system is established, and a significant criterion N is to evaluate the bearing behavior of the weld seam. The weld seam of vehicle bracket is classified into three types, the range of safety factor is determined to each type of weld seam. At the end, we calculate the compound stress of different weld seam and compare the safety factor of different length and the results show that it is suitable when the total length of the weld seam is 1200mm.