&lt;b&gt;A methodology for analysis of defective pipeline by introducing stress concentration factor into beam-pipe finite element formulation

Hsu Yang Shang

doi:10.4025/actascitechnol.v38i3.27988

<b>A methodology for analysis of defective pipeline by introducing stress concentration factor into beam-pipe finite element formulation

Hsu Yang Shang

Open Access

https://doi.org/10.4025/actascitechnol.v38i3.27988

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Abstract

This work proposes a methodology for defective pipe elastoplastic analysis using the Euler Bernoulli beam-pipe element formulation. The virtual work equation is modified to incorporate the stress concentration factor in beam-pipe element formulation. The stress concentration factor is evaluated a priori by a 2D or 3D finite element model according to the defect profile. In this work, a semicircular defect and a rectangular defect are considered. The stress concentration factor is inserted into the beam-pipe element elastoplastic formulation, and several applications are presented to show the applicability of the proposed method.

Highlights

Steel pipelines are widely used for conveying natural gas and crude oil, and their derivatives
The pipeline is typically constructed from carbon steel, because of its high mechanical strength, and because it is cheaper than other materials
Observe that the results provided by the APC3D without tangential stress concentration factor (SCF)

Summary

Introduction

Steel pipelines are widely used for conveying natural gas and crude oil, and their derivatives. The equilibrium equation for elastoplastic analysis is solved by the total Lagrangian formulation It incorporates a stress concentration factor into a three-node beam-pipe element formulation. This methodology unifies the global analysis of the pipeline, simulated by the Euler Bernoulli beam-pipe model by means of beam elements, with the local analysis of the defective pipe. A brief literature review is presented concerning a stress concentration study in defective pipes with a finite element method developed for pipeline elastoplastic analysis. The methodology includes the stress concentration effect at the tip of the defect, and a further probabilistic analysis was presented Another analysis has presented a local fracture criterion of a pipe with notch-type defects based on 3D finite element formulation (Oh, Kim, Baek, Kim, & Kim, 2007). The equations for stress and strain increments for a pipe in the longitudinal and tangential directions are given by Equations 6 at 9:

Sθ t o

Analysis of pipe with semicircular defect subjected to bending

Analysis of pipe with rectangular defect subjected to internal pressure

Conclusion