Creep analyses for pipe bends under combined internal pressure and bending loads. (October 2021)

• Record Type: Journal Article
• Authors: Li, Jian; Zhou, Chang-Yu; Zhu, Jian-Guo; Wang, Xiao-Yu
• Is Part Of: International journal of pressure vessels and piping. Volume 193(2021)
• Publication Date: 2021-10
• Subjects: Pipe bends -- Creep -- Failure life -- Geometry non-linearity; Pressure vessels -- Periodicals; Pipe -- Periodicals; Récipients sous pression -- Périodiques; Tuyaux -- Périodiques; Pipe; Pressure vessels; Periodicals; 681.76041
• DOI: 10.1016/j.ijpvp.2021.104450
• Languages: English
• ISSNs: 0308-0161

Abstract

Abstract: This work provides detailed analyses of creep behaviors considering the influence of geometry change for pipe bends under combined bending and internal pressure loads based on the finite element method (FE). A modified Karchanov‒Rabotnov (K‒R) equation for creep damage is used in the ABAQUS user defined material subroutine (UMAT) compiled by FORTRAN. Typical results of creep stress, damage, and deformation for pipe bends are presented. Creep relaxation and damage evolution will happen during the creep procedure. The damage evolution procedure seems contrary to that of stress redistribution. There are some differences between the deformation distributions when using geometric non-linearity (GNL) and no GNL, and also the results of stress, damage, and creep failure life for pipe bends show a corresponding distinction. Phenomena of the differences of pipe ovality for pipe bends under different loading types can supply some evidence to explain the failure trait. Pipe bends are stiffened as the GNL choice hinders the deformation, so GNL has a positive effect on creep failure life prediction for pipe bends under combined loadings. Highlights: A modified Karchanov-Rabotnov equation for creep damage is used. Creep relaxation and damage evolution happens during creep procedure. There are some differences using GNL and no GNL. GNL has a positive effect on creep failure life prediction for combined loading.