Load Bearing Capacity of a Dented Aluminum Pipe Subjected to Internal Pressure Considering the Effect of Ductile Damage

R Akbari Alashti,S Jafari,S.J Hosseinipour

doi:10.1590/1679-78251383

Abstract

In this paper, the effect of ductile damage on the behavior of a dented Aluminum pipe subjected to internal pressure is investigated. The plastic behavior of pipes under indentation is studied using continuum damage mechanics theory and the elastic-plastic finite element analysis. Finite element calculations are carried out using the damage plasticity model proposed by Xue and Wierzbicki. The proposed damage plasticity model incorporates effects of both hydrostatic stress and the Lode angle to define the fracture envelope. Numerical calculations for different ranges of internal pressures and indenter diameters with and without damage effect are carried out and results are compared. It is shown that damage has a significant effect on the load bearing capacity of an indented pipe. Results of the present study confirm the credibility of the proposed model in predicting the ductile fracture under multi-axial state of stress loadings.

Highlights

Pipelines are widely used for transmission of gases and liquids from production sites to end users with a reasonably good safety record which is mainly due to appropriate design process, material selection and operating practices (Hyde et al 2005)
The target dent depth as an indication of load bearing capacity for each combination of indenter diameter and internal pressure is obtained when the value of the non dimensional damage parameter becomes equal to unity
It is found that when the maximum von Mises stress reaches to 670MPa, the dent depth increases as the indenter diameter increases

Summary

Introduction

Pipelines are widely used for transmission of gases and liquids from production sites to end users with a reasonably good safety record which is mainly due to appropriate design process, material selection and operating practices (Hyde et al 2005). One of the most common causes of failures in onshore and offshore structures, oil and gas transmission pipelines is dent. A dent in a pipeline is considered as a permanent plastic deformation of the cross-section of the pipe that causes a local stress and strain concentration and a reduction in the pipe diameter Akbari Alashti et al / Load Bearing Capacity of a Dented Aluminum Pipe. There are different types of pipeline dents which are defined according to their degrees of impact on the pipeline wall dimensions and geometries (Alexander, 1999, Allouti et al, 2012)

Methods

Results

Conclusion