Electrothermal Distortion Analysis and Structural Strain Assessment of Vehicle Cable Terminals Under Bending Stresses

This paper proposes a set of bending constitutive equations that aid in comprehending the failure mechanism and evaluating the structural strain experienced by vehicle cable terminals when subjected to bending stress. Firstly, the actual vehicle cable terminal used in high-speed trains is simplified and modeled as a cylindrical laminated insulation composite structure (CLS). Based on that, bending constitutive equations, as well as the electrical field distribution equations and thermal field equations of the CLS are established. The stress and strain distribution characteristics of the CLS are then simulated via finite element simulation, and it is found that the electric field and temperature gradient of the insulation layer change irregularly based on the strain. Finally, the applicability of bending constitutive equations is verified through a real physical model and omnidirectional strain monitoring experiment. The results reveal that strain is distributed in a "sine” shape under various bending radii which results in strain being closely linked to the deformation of the electrical and temperature fields. The utilization of strain gauges for measuring axial and circumferential strain in the insulation layer yields sine-shaped patterns with amplitudes of 20% and 7%, respectively. These results provide further insights into the factors influencing the distortion of the electric heating field. Moreover, they serve as a foundational reference for the assessment of structural strain in vehicle cable terminals. The mechanism of insulation deterioration can be revealed from a novel perspective of structural strain, which greatly promotes the research and development of intelligent online monitoring system for vehicle cable terminals.