Nonlinear thermal responses of the cracked pipeline rehabilitated by the FGP-GPLs liner with an oval-shaped cross-section

Subsea pipelines are subjected to damage following extended operational periods. A cost-efficient and effective trenchless remediation approach is to install flexible thin-walled liners for continued operation. However, oval-shaped imperfections may happen in the liner because of problems including under-dilatation, distortion of the original pipeline, and faulty joint alignment in engineering applications. This investigation reveals stability characteristics for the encased functionally graded porous (FGP) liner with an oval-shaped cross-section consolidated by graphene platelets (GPLs) within a heating field. The Halpin-Tsai micromechanics approach and Gaussian random field are utilized to characterize the distributed pattern of the porosity and GPLs within the cross-sectional view of the liner. Geometric nonlinearity is considered. A formula for displacement is presented to outline the radial deflection in the FGP-GPLs oval liner. Utilizing the thin-walled shell principle and energy criterion, the temperature-displacement equilibrium path is predicted, and the minimum/critical temperature variation is deduced. Thereafter, comparative examinations are carried out with the results of other investigations. Good accordance indicates the present study is efficient and accurate. Finally, a parameter assessment is accomplished by looking into the impacts of pores, the weight fraction of the GPLs, and ovality on the anti-buckling responses. The conclusion shows that both minimum temperature variation and critical temperature variation decrease by 24.7 % as the ovality increases from 0 % to 10 %.