Finite Element Simulation For Laser Deposition Procss Of Graphite Copper Functionally Gradient Composite Of Thermal Stress

The graphite copper functional gradient composites has excellent electrical, thermal,self-lubricating properties, it has a very broad prospect for the application of Railtransportation、Electric power transmission. In this paper, the temperature field and stress fieldof laser deposition process for graphit copper functionally gradient composite is simulated byANSYS software.The process of DMD for multiple layers welding and single run was computed by thetechnology of APDL secondary development and Element birth and death, and the stress fieldof deposited alloys was computed by using the coupling method. The stress field offunctionally gradient composites and homogeneous is established. And obtained the crackingmechanism of the effect of laser power, scan velocity, laser scanning mode, gradientdistribution index, layers, layer thickness. In the paper the following conclusions are made:(1) Homogeneous’s residual stress is higher than the functionally gradient composites,And large stress is spread across the space. The equivalent residual stress of functionalgradient composites gradually become smaller from bottom to top, it shows that gradientstructure has the modifying effect on residual stress.(2) In the range of3600W to4200W for laser power, the average value of residual stressfilms firstly increases and then decreases with the increase of the laser power. And theminimum residual stress when the lasr power is4200W. In the range of200mm/min-400mm/min for scan velocity, the average value of X-Component of stress alongthe parallel path of the x axis films firstly decreases and then increases with the increase of thescan velocity.And the minimum residual stress when the scan velocity is300mm/min.So themost optimal laser power and scan velocity range is4000W-4200W and300mm/min-400mm/min respectively.(3) In the contrast between the vector scanning and the grating scanning, and showed thatthe stress field of grating scanning is not only smaller but also more evenly.(4) In the range of0.25to4for gradient distribution index, the residual stress level in thespecimens is lower when gradient distribution index p=1. In the range of0.4mm-0.8mm forlayer thickness and the range of6-10for layers, the residual stress films increases with theincrease of layer thickness and layers. By comprehensive comparison, the thickness of0.6mmand the layers of8and the gradient distribution index of1is the best gradient structure.(5) the maximum X-Component of stress along the parallel path of the x axis at the scaleof2mm or31mm, there is larger residual stress and the high incidence area of crack. The Y-component stress along the parallel path of the Y axis had W shape that the middle and theboth sides of deposited part had larger residual stress. And the Z-component stress along theparallel path of the Z axis is gradually decreasing from bottom to top of the deposited parts, itis that prone to cause the crack between substrate and sediments.