Analysmetoder för rörsystem

• Main Author: Holmberg, Erik
• Format: Others
• Language: Swedish
• Published: Linköpings universitet, Institutionen för ekonomisk och industriell utveckling 2008
• Subjects: rör; bockning; ovalitet; godsförtunning; spänningsanalys; kollaps; FEM; Finita elementmetoden; Abaqus; implicit; explicit; TECHNOLOGY; TEKNIKVETENSKAP
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15678

The purpose of this thesis work is to evaluate how the physical behaviour of a pipe bend is affected by the pipe bending procedure. Effects such as initial ovalization, thinning, thickening and plastic hardening from the bending procedure are examined and the mechanical properties of pipe bends containing these effects are investigated. This has been evaluated by creating a detailed Finite Element model of a pipe that is being bent. Then the differences compared to a bent tube in a virgin state, so called Elbow elements and an analytical in-house program have been evaluated. The virgin state refers to a model of a pipe that is bent from the beginning, thus having a homogeneous thickness and not containing any plastic hardening. The Elbow element is a calculationally cheap element, specially developed for accurate calculations of pipe bends in an initially virgin state. The goal with the thesis work is to get a better picture of what happens to a pipe as it is being bent, how this affects the mechanical properties and to evaluate the possibility to develop an easy method for taking these effects into account when using the Elbow element. This report describes the layout of the work and how the detailed FE-model has been constructed. One step to being able to use the Elbow element with respect to changes in shape and plastic hardening from the manufacturing process has been presented, the differences are though considered being too big to be able to use the Elbow elements with enough confidence in the results. The problems that remain are presented and discussed and proposals for further work are presented.