A Novel Finite Element Model for Simulating Residual Stress in Laser Melting Deposition

Abstract

The geometry of the cladding pass cross section cannot be easily predicted in laser melting deposition. Due to the huge difference between the actual and the predicted cross section, it is difficult to conduct numerical simulations. In this paper, the finite element method (FEM) with thermal–mechanical coupling is performed. A novel cladding pass cross section model, isosceles trapezoid model, is proposed. The comparisons between the isosceles trapezoid model and the traditional model (disk model and rectangle model) are performed in terms of geometrical deviation, heat dissipation, temperature field, and stress field. The results show that the geometrical deviation and heat dissipation between trapezoid model and disk model is small, and that between trapezoid model and rectangle model is large. The trapezoid model has an additional degree of freedom for modeling, i.e., contact angle, which helps to conform complex cross section geometry more flexibility. The results of temperature field and stress field show that the deviation between the isosceles trapezoid model and the traditional models is small on the upper surface of the sample, and rectangle model has worse prediction results than the other two models at the interface between cladding pass and substrate. Finally, the validation experiment is carried out and the stress is measured by laser ultrasound technique. The experimental result matches the FEM result based on isosceles trapezoid model.