In-plane nonlinear localised lateral buckling of straight pipelines

The lateral buckling problem for thermally loaded pipelines is known to involve a localisation phenomenon within a limited region of the pipeline rather than an extensive global mode shape. In this paper, a strategy is presented to investigate the localised lateral buckling of pipelines under thermal loading and friction whereupon the constitutive relations are derived for thermal stress and finite strain based on a hyperelastic constitutive model. Using this hyperelastic formulation, we investigate the critical overall pipeline length above which localised buckling remains unchanged. The results show that increasing the length of the pipeline or changing the end boundary conditions when the pipeline length is greater than or equal to the critical overall length does not influence the localised buckling behaviour. The solutions to several examples are compared with the results in the literature and validated by use of the finite element package ANSYS. Parametric studies on diameter, imperfection, friction and shear deformation effects are subsequently performed on examples that identify which factors influence the localised buckling of thermal pipelines.