Tensile damage and load-bearing performance of Mark III LNG containment insulation under different temperature fields

Objectives To address the stress concentration and tensile damage that may occur in the connection regions of the cargo containment system insulation layer due to structural discontinuities under the combined effects of tensile and thermal loads during LNG transportation, this study investigates the load-bearing performance and damage behavior of the insulation layer under uniform temperature conditions and non-uniform temperature fields induced by the temperature difference across the containment system, and further examines the effects of key structural parameters. Methods A thermo-mechanically coupled finite element model of the insulation layer was established in Abaqus and validated against published experimental results. The tensile responses under 25°C, uniform -163°C, and non-uniform temperature-field conditions were compared, and the effects of polyurethane foam density and epoxy adhesive-layer thickness were further investigated. Results The results showed that, compared with the 25°C condition, the ultimate load of the insulation layer under the uniform -163°C condition increased by approximately 43%, while the fracture displacement decreased by approximately 21%, indicating a pronounced low-temperature strengthening effect. Compared with the uniform -163°C condition, the non-uniform temperature field reduced the ultimate load by approximately 11.3% and increased the fracture displacement by approximately 22%, with more pronounced progressive damage. Increasing the polyurethane foam density generally enhanced the ultimate load-bearing capacity but reduced the fracture displacement. The adhesive-layer thickness had a non-monotonic effect on the load-bearing performance, and a thickness of 2mm exhibited favorable overall performance within the investigated range. Conclusions The temperature-field distribution and key structural parameters significantly affect the tensile load-bearing and damage behavior of the Mark III insulation layer. In particular, accounting for non-uniform temperature fields is important for evaluating structural performance under realistic low-temperature conditions, providing a reference for strength assessment and parameter optimization of LNG containment systems.