Product Code: ICAL07_1808

A Coupled Time-Dependent Numerical Simulation on Temperature and Stress Fields in Laser Solid Freeform Fabrication Process
Authors:
Masoud Alimardani, Department of Mechanical and Mechatronics Engineering, University of Waterloo; Waterloo ON Canada
Ehsan Toyserkani, Department of Mechanical and Mechatronics Engineering, University of Waterloo; Waterloo ON Canada
Jan P. Huissoon, Department of Mechanical and Mechatronics Engineering, University of Waterloo; Waterloo ON Canada
Presented at ICALEO 2007

This paper presents a coupled 3D time-dependent numerical approach for modeling laser solid freeform fabrication by which the geometry of the deposited materials, temperature distribution, and stress field can be predicted throughout the process. In the proposed method, coupled thermal and stress distributions are numerically obtained assuming the interaction between the laser beam and the powder stream is decoupled. Main process parameters affected by a multilayer deposition due to the formation of non-planar surfaces such as powder catchment efficiency are incorporated into the modeling. To practice the proposed algorithm, fabrication of a four-layer thin wall of AISI 4340 steel is modeled. The geometry of the wall, the temperature, and the stress fields across the modeling domain are studied throughout the fabrication process. The model is then used to investigate the effects of preheating, and clamping the substrate to the workstation. Results show that preheating improves the process by reducing the thermal stresses as well as the settling time for the formation of a steady-state melt pool in the first layer. The results also indicate that clamping the substrate decreases thermal stresses at its critical locations (i.e. deposition region). The reliability and the accuracy of the model are experimentally verified.