Residual Stress and Distortion Prediction for Laser Directed Energy Deposition Based on Cyclic Heat Transfer Model

Abstract

Predicting the residual stress and distortion caused by inhomogeneous temperature fields in the laser directed energy deposition (LDED) process is a challenging task. This study proposes a novel thermodynamic coupling simulation method based on the cyclic heat transfer model to accurately predict temperature, stress, and distortion evolution during the deposition process. The model effectively calculates the layer-by-layer superposition of thermal effects and cyclic accumulation of thermal stress during the deposition process, leading to improved prediction accuracy for temperature, residual stress, and distortion. Initially, the heat source model, the cyclic heat transfer model, and the thermoelastic matrix are established. The thermoelastic constitutive equation and the equilibrium differential equation are formulated to capture the actual process characteristics of the LDED accurately in order to achieve the thermodynamic coupling solution. Then, numerical simulations are performed on a typical model specimen, with simulation parameters consistent with the actual deposition parameters. Finally, the predicted results are validated through actual deposition experiments, and the temperature, stress, and distortion history are analyzed. The results demonstrate that the cyclic thermodynamic coupling model proposed in this study can effectively predict the deposited components’ temperature, residual stress, and distortion evolution. This study establishes a crucial foundation for achieving precision and performance control in the deposition process and reducing residual stress and distortion in the components.

Keywords

• Laser directed energy deposition (LDED)
• cyclic heat transfer model
• thermodynamic coupling
• residual stress
• distortion