Thermo-mechanical analyses for optimized path planning in laser aided additive manufacturing processes

Laser deposition strategies can have significant effect on the temperature distribution for multi-bead multi-layered additive manufacturing. Its influence on thermal field will affect the induced residual stress and distortion. In this paper, a computationally efficient numerical model for Laser Aided Additive Manufacturing (LAAM) process was developed for evaluating deposition strategies and understanding how their dynamic temperature evolution can cause significant differences in the residual stress and distortion. The numerical model was calibrated with experimental clad bead dimensions and process parameters for depositing multi-bead SS316L onto the substrate of the same material. The numerical model was validated with experimental results for depositing a rectangular clad layer on a 3 mm thick substrate using Zigzag strategies along the width (x-axis) and length (y-axis) directions. Temperature field measurements using infrared camera and X-ray diffraction residual stress field measurements agreed well with numerical results. The predicted residual stress field showed that the approximately 2.3 times larger distortion along the y-axis direction in width-wise Zigzag scanning is caused by non-uniform stress distribution in the y-axis direction. However, width-wise Zigzag scanning leads to more homogeneous stress distribution in the x-axis and therefore lower distortion in the x-axis direction compared to length-wise Zigzag scanning.