# Thermal-Structural Coupling Analysis of Subsea Connector Sealing Contact
## 6 Conclusions  
In this article, the heat transfer model of the subsea connector is established and solved, and the steady-state temperature distribution of the connector is obtained. Considering the stress and deformation of the subsea connector under the thermal load, the thermal-structural coupling analysis model of steady-state temperature field is established. The theoretical analysis of thermal stress of the key sealing structures of the connector is compared with the numerical simulation, and the pressure shock mode under the steady-state temperature field is also analyzed. It is proved that the coupling mathematical model proposed in this article can be applied to the thermal-structural coupling theoretical analysis of the similar subsea oil and gas equipment. The main conclusions are as follows: \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Time** **(s)**} & \multirow{2}{*}{\
\begin{tabular}{c} **Maximum** \\ **Contact Stress** \\ **(MPa)** \\ \end{tabular} } & \multicolumn{3}{c}{**Maximum Equivalent Stress (MPa)**} \\ \cline{3-5}  & &
\begin{tabular}{c} **Lenticular** \\ **Sealing Gasket** \\ \end{tabular} & **Hub** & **Finger** \\ \hline
10 & 458.76 & 251.85 & 176.64 & 111.79 \\
20 & 492.59 & 275.22 & 195.21 & 113.00 \\
30 & 459.06 & 251.88 & 176.99 & 111.87 \\
40 & 458.76 & 251.85 & 176.64 & 111.87 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Contact stress and equivalent stress of the main sealing structures in every stage in the pressure shock mode. Figure 18: Maximum contact stress and equivalent stress changing with the oil and gas pressure in the pressure shock mode. (**a**) Maximum contact stress; (**b**) Maximum equivalent stress. 1. Considering the heat transfer problem of the subsea connector in deep water, the equivalent heat transfer models of seawater layer between the lenticular sealing gasket and hubs, between hubs and fingers, and outside the outer surface of the fingers and the press ring are established, and the relationship between equivalent thermal conductivity, composite heat transfer coefficient, and temperature is solved. 2. The mathematical model of steady-state thermal structural coupling of the subsea connector is established and verified by the simulation analysis. The theoretical analysis of the radial stress, circumferential stress, and axial stress is 5.28%, 8.82%, and 5.32% larger than the simulation analysis, and the sealing width is 12.10% smaller. 3. The steady-state temperature distribution of the subsea connector under rated working condition is simulated. The finite element simulation shows that in the center path of the connector's lenticular sealing gasket, the hub's falling temperature is 60.01 \({}^{\circ}\)C and the temperature gradient is \(-\)1.05 \({}^{\circ}\)C/mm, which are the maximum values of all parts. The values of the sealing gasket, finger, and press ring decrease in turn. The temperature field of the lenticular sealing gasket is symmetrically distributed, and the temperature is always in the high temperature stage (126\(\sim\)150 \({}^{\circ}\)C), which has little influence on the mechanical properties of the material, so as to ensure its stable sealing performance. 4. The numerical simulation of pressure shock mode under steady temperature field shows that the maximum equivalent stress of the sealing gasket exceeds the theoretical yield limit of the material under the combined action of temperature and pressure, resulting in plastic deformation, which indicates that the lenticular sealing gasket is sensitive to high pressure shock under high temperature. Conceptualization, F.Y., B.L. and X.X. ; methodology, F.Y. and X.W. ; validation, B.L., X.H. and D.L. ; formal analysis, X.X., K.J. and L.W. ; investigation, D.L., P.J. and Z.Y. ; resources, Z.Y., P.J. and L.W. ; data curation, D.L., X.H. and X.W. ; writing--original draft preparation, F.Y., X.X. and D.L. ; writing--review and editing, F.Y., K.J. and D.L. ; funding acquisition, L.W. and F.Y. All authors have read and agreed to the published version of the manuscript.