Investigation of thermal contact conductance of bolted flange structures based on experiments and finite element inverse analysis

The investigation of the thermal contact conductance (TCC) of bolted flange structures is of great significance for the thermal design optimization and service reliability of the relevant equipment. In this study, three types of bolted flange structures are utilized for the purpose of experimental investigation: aluminum alloy/aluminum alloy, aluminum alloy/stainless steel, and aluminum alloy/titanium alloy. The focus of the study is the examination of the effects of temperature, bolt torque, and material combination on TCC. Multi-factor sensitivity analysis is performed using the random forest algorithm. The results suggest that, for the bolted flange structures and experimental conditions examined in this study, the equivalent uniform TCC model produces more stable and physically consistent results. Of the three factors that were the focus of the investigation, temperature was found to have the most significant impact, accounting for 59.27% of the total feature importance. It is evident that the TCC increases concomitantly with the rise of bolt torque; however, the growth rate gradually slows down. In the present study, the three combinations under investigation were found to exhibit varying levels of TCC. The aluminum alloy/aluminum alloy interface was found to exhibit the highest level of TCC, while the aluminum alloy/titanium alloy interface was found to exhibit the lowest. The mean error of the transient simulation employing the TCC obtained by steady-state inversion is approximately 3.40% and 1.04%, which demonstrates good reliability. This study elucidates the relationships between temperature, bolt torque, material combination, and the macroscopic equivalent TCC, providing a reference for thermal analysis and thermal design of relevant engineering structures.