Theoretical Predictions and Computational Verifications on the Instability Responses of FGP-GPLs Subsea Pipelines with Egg-Shaped Cross-Sections

This paper primarily refers to the nonlinear instability of functionally graded porous (FGP) egg-shaped subsea pipelines mixed with graphene platelets (GPLs) under pressure and thermal environments. The FGP-GPLs egg-shaped subsea pipeline deflects radially inward since the pipeline is confined tightly and rigidly by the medium (soils/rocks). This deflection may be represented by a refined available displacement formula. The response curves are effectively traced by associating the computational calculus and the thin-walled shell theory. Furthermore, numerical verifications are completed to validate the analytical schemes. It is seen that the numerical curves are closely fitted to the theoretical ones. Moreover, the current study is validated efficiently by other results. Finally, evaluations are conducted on some parameters that affect the instability of the FGP-GPLs subsea pipeline with an egg-shaped profile, including the porosity coefficient, geometric shapes, weight fraction, temperature variations, etc.