# Thermo-Mechanical Coupled Analysis of Electric Vehicle Drive Shafts
## 2 Finite Element Method for CV Joint
Due to these advantages, it is widely utilized across various industries, including automotive crash analysis, explosion studies in defense applications, and impact analysis [27; 28; 29; 30; 31; 32; 33; 34]. Conversely, the thermal analysis capabilities of Ansys Mechanical employ an Implicit analysis method, which offers the advantage of delivering results efficiently even for extended simulation timeframes. Furthermore, it supports the application of diverse thermal boundary conditions, enabling more realistic and accurate analysis outcomes. These features make it particularly effective for analyzing structural deformations due to thermal expansion and evaluating thermal stress through integration with structural problems. In this study, LS-Dyna was utilized to simulate the initial short-term behavior and then calculate the temperature of critical components due to internal frictional stresses. Based on these results, a simulation procedure was established to predict nonlinear thermal phenomena and their locations during extended operation. To ensure the reliability of the analysis, temperature changes at measurable points identified in physical experiments  
Figure 1: Schematic of ball spline joint. were observed and compared with the simulation results for validation. The analytical process employed in this study is illustrated in Figure 2.  
As shown in Figure 2, this study utilized ANSYS Workbench to establish the pre-processing framework for the analysis. Through this platform, a K-file containing the necessary information for the analysis was generated and formatted for compatibility with LS-Dyna. The K-file serves as an input data file that includes the geometric details of the analysis model, such as nodes and element information. Specifically, it contains the coordinates of nodes (spatial locations of each point) and the connectivity information of the elements, allowing the program to recognize the relationships between nodes. Additionally, the K-file incorporates various physical properties such as elastic modulus, density, and plastic deformation parameters, ensuring an accurate representation of real-world operating conditions. To conduct the dynamic analysis, the model defines initial conditions and external loading information, including friction coefficients, contact stiffness, and penetration tolerance, which characterize the contact interactions. This setup enables the simulation of complex physical interactions between components within the model. In Solve Process 1, a thermo-structural coupled model in LS-Dyna was employed to perform dynamic analysis. Key results such as deformation, stress, and velocity were reviewed, with a particular focus on thermal analysis. In Solve Process 2, the thermal variations obtained from the LS-Dyna analysis were verified and incorporated into the Ansys Transient Thermal model for extended thermal analysis. The workflow of this study was designed as an integrated model linking LS-Dyna and Ansys Transient Thermal, ensuring that both analyses shared the same mesh elements. This setup enabled the mapping of results calculated in LS-Dyna onto the Thermal model, allowing for additional long-term thermal behavior analysis. In Solve Process 2, heat flux values at individual nodes, derived from the short-term dynamic analysis in LS-Dyna, were extracted and applied to the Ansys Transient Thermal model. Using this input, an extended thermal analysis was conducted to evaluate long-term behavior. The accuracy of the analysis was validated by comparing the simulation results with experimental data. The methodology proposed in this study enables an efficient thermo-structural coupled analysis of high-speed rotating components, contributing to improved design reliability under high-temperature and high-load environments.