Residual stress control in DMD process

Abstract

The material fabricated by the Laser aided Direct Metal Deposition (DMD) process experiences extreme cyclic thermal loads during the process, which builds relatively high residual stress. The residual stress is directly related to fracture and fatigue behavior of the product; therefore, controlling residual stress in DMD process is essential. However, online monitoring of mechanical deformation is difficult and requires high costs. In this study, the numerical models developed in the Center for Laser Aided Intelligent Manufacturing (CLAIM) at University of Michigan have been used to find the techniques to control mechanical deformation in the stage of generating tool paths using CAD program. The numerical studies include the investigation of effects of scanning direction and the number of laser scanning for a given height of the layer on residual stress in DMD process.The material fabricated by the Laser aided Direct Metal Deposition (DMD) process experiences extreme cyclic thermal loads during the process, which builds relatively high residual stress. The residual stress is directly related to fracture and fatigue behavior of the product; therefore, controlling residual stress in DMD process is essential. However, online monitoring of mechanical deformation is difficult and requires high costs. In this study, the numerical models developed in the Center for Laser Aided Intelligent Manufacturing (CLAIM) at University of Michigan have been used to find the techniques to control mechanical deformation in the stage of generating tool paths using CAD program. The numerical studies include the investigation of effects of scanning direction and the number of laser scanning for a given height of the layer on residual stress in DMD process.