Using XFEM to Predict the Damage with Temperature of the Steel Pipe Elbows under Bending and Pressure loading

Abdelkader Brakna,Elamine Abdelouahed,Habib Benzaama,Kouider Madani,Moahmed Mokhtari,Nourddine Hammadi

doi:10.3221/igf-esis.55.27

Abdelkader Brakna, Elamine Abdelouahed + Show 4 more

Open Access

https://doi.org/10.3221/igf-esis.55.27

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Abstract

The pipes, during their service, are subjected to accumulated loads such as internal pressure and that of the soil. The latter considerably accelerate their damage. In this work, the bending moment stress of API 5L X70 category steel elbows under thermo-mechanical behavior and in the presence of pressure were studied. We used FEM (finite element method) through the numerical calculation code ABAQUS and the XFEM technique for structural damage while using solid elements as a structure. Our objective is to evaluate the response and resistance capacity of the steel elbow by its location in the tube–elbow-tube system under a mixed loading of pressure and moment for all scenarios. It is based on a single standardized dimensioning of the elbow (diameter and thickness). The effect of several parameters has been studied such as the type of loading and the pressure levels, which are clearly conditioned by the level of damage. Numerical damage results are presented by moment-rotation curves. They illustrate the variation in damage as a function of these effects which act simultaneously.

Highlights

The elbow, in its geometric configuration, will cause a variation in stress along its lower surface and upper surface and by several possible loading conditions, giving rise to several types of damage
Several researches have been focused on the understanding of the mechanical behavior of these elbows; these researches were started by the analytical work of Von Karman [1] where he used a formulation between the longitudinal deformation due to bending and that due to ovalization
Others add pressure in tests such as Gresnigt et al [6] where they have developed with van Foeken [7] an analytical model for the transverse deformation of elbows by introducing a correction factor to take into account the influence of elbow parameters on its ovalization

Summary

Introduction

The elbow, in its geometric configuration, will cause a variation in stress along its lower surface and upper surface and by several possible loading conditions, giving rise to several types of damage. Rodabaugh and George [2], improved this solution by introducing internal pressure Other researchers such as Karamanos and Shalaby [3], concluded that under heavy loading the elbow ovalization due to stresses and strains is greater in the circumference than in the longitudinal. They concluded that the response under closing bending moments is different from that of opening. Shao [11] evaluated thermal stresses as well as Kandil et al [12] by the digital model Several researchers such as Greenstreet [13], Hilsenkopf, Suzuki and Nasu [14] experimentally tested elbows with different dimensions under different loading modes and compared their results by numerical methods. Curves show the response of structures to loading until they fail

Objectives

Conclusion