# An Accurate CFD-FEM Model for the Thermal Stress of the Simulation of Selective Laser Melting

## TL;DR

This paper introduces a new model combining CFD and FEM to accurately predict thermal stress in selective laser melting, improving understanding of defect formation and stress distribution.

## Contribution

The study proposes an accurate and efficient thermo-mechanical analysis method combining CFD and FEM for micrometer-scale SLM stress prediction.

## Key findings

- Surface undulations and lack-of-fusion regions show significant stress concentration, with local residual stress reaching approximately 900 MPa.
- Regions with smooth surface geometry exhibit stresses of about 650 MPa, showing a positive correlation between surface quality and stress concentration.
- The model provides a new theoretical basis for understanding defect formation and optimizing scan paths in SLM components.

## Abstract

Selective laser melting (SLM) is a 3D printing technology for precision manufacturing. Owing to its high forming accuracy, parts fabricated by SLM can often be used directly without secondary machining. Consequently, the stress field in the structure, especially local stress concentration in small regions, is of great importance. Building on our previous work, this study proposes an accurate and efficient thermo-mechanical analysis method that combines a computational fluid dynamics (CFD) model and a finite element method (FEM) model for stress prediction in micrometer-scale SLM. Compared with the conventional element birth–death method, the present model more faithfully reproduces the SLM process and the post-solidification morphology and stress distribution. Numerical simulation of a single-track TC4 scan shows that pronounced surface undulations and lack-of-fusion regions exhibit significant stress concentration: the local residual stress can reach approximately 900 MPa, whereas regions with relatively smooth surface geometry exhibit stresses of about 650 MPa. This indicates a clear positive correlation between surface quality and stress concentration. The results provide a new theoretical basis for understanding defect formation mechanisms, spatial stress distribution, and scan-path optimization in SLM components.