# Finite Element Analysis of Thermal Stress and Thermal Deformation in Typical Part during SLM
## 1 Introduction
(2018) [28] used the ANSYS APDL language to simulate the model (\(1\times 0.26\times 0.025\) mm) molten pool and residual stress under different laser power values (8-14 W) as well as scanning speeds (100-400 mm/s). It was verified through experimental thermal stress results that the stress was mainly concentrated at the middle of the first scanning track, the terminal of each scanning track, and the edges of the forming surface. However, for this traditional finite element simulation, it was required to establish a finite element life-death model, a heat source movement algorithm based on ANSYS, ABAQUS, or MATLAB, along with a high amount of cell grid data processing for the calculation efficiency to exceed the technological requirements. Therefore, in the previous literature, only a few temperature fields (track 5 [17]) or simple model thermal field simulations have been completed through an expansion in the mesh size or decrease in the process parameters. In contrast, the influence of multi layers (such as through melting) was not clear during the layer-by-layer processing and the integral forming simulation of typical parts was almost non-existent. Similarly, few reports with related experiments, analysis, and statistical studies exist on the manufacturing error evaluation of AM under thermal stress. [PERSON] and [PERSON] (2001) [29] studied the planar error. [PERSON] et al. (2001) [30] and [PERSON] et al. (2002) [31] calculated the volume error of AM. [PERSON] et al. (2008) [32], [PERSON] and [PERSON] (2010) [33], and [PERSON] et al. (2000) [34] conducted several experiments and statistical studies to analyze the relationship between partial errors and process parameters during AM. [PERSON] and [PERSON] (2011) [35] analyzed the cylindrical errors of AM parts through geometric modeling techniques. Moreover, [PERSON] and [PERSON] (2013) [36] developed a statistical analysis method to calculate the influence of metal shrinkage on the shape error of AM parts as well as to generate parametric equations to associate the errors caused by shrinkage to the process parameters. In addition, [PERSON] et al. (2014) [37] analyzed part deformation conditions of the SLM technique through forming errors. Additionally, an error model evaluation simulation of parts, formed during melting and solidification shrinkage (0.1/0.2 mm), was developed. According to the literature, the universal applicability of such results is so limited that the experimental research could not be regularly conducted during SLM. Simultaneously, low efficiency simulation has led to the negative overall effect of certain parts through poor predictions, especially during variable cross-section forming. As an example, a certain amount of stress concentration caused failure, but it was difficult to measure and simulate. Consequently, the efficient simulation of complex parts on forming quality has higher practical significance. The research object of this paper was a typical thin and hollow plate part. The structure had a thin panel and a water cooling channel at the middle of the panel for heat dissipation, while a barbed water nozzle interface with the hose was provided with the panel. In traditional processes, it is also necessary to combine the milling with a traditional machining center, along with the welding of the upper and lower boards to manufacture this part. Therefore, quality control is difficult. Consequently, an enterprise will attempt to adopt an SLM process. However, due to the warping caused by thermal deformation, many problems still exist in actual production such as the high flatness errors of the panel, the imprecision of the cylindricity values of the two nozzles, and the variation in the center distance between the two nozzles. As the new process would still produce a high amount of waste, a thermodynamic coupling algorithm based on welding software was developed in this paper, while the forming process simulation of a part was conducted.