Numerical analysis of the elastic-plastic behavior of a tubular structure in FGM under pressure and defect presence

A Houari,A.S Bouchikhi,Kouider Madani,M Mokhtari

doi:10.3221/igf-esis.59.16

Abstract

Given the field of application and the many advantages, the use of FGM (Functionally Graded Materials) materials has recently been extended in several components and more particularly in cylindrical structures, which have been the subject of several recent studies. Our work aims to use the finite element method to analyze a cylindrical structure in FGM with properties gradated in the direction of the radius (Thickness) solicited purely in internal pressure by the implementation of a UMAT subroutine in the calculation code ABAQUS. The elasto-plastic behavior of the FGM is described by the flow theory represented by the equivalent stress of Von Mises and an incremental hardening variable. The TTO model (Tamura-Tomota-Ozawa) was used only to determine the elastic-plastic properties of the FGM material. The radial, tangential and axial stresses according to the thickness were evaluated in the first part of our work. In the second part, these stresses are evaluated under the same conditions but with the presence of a micro-cavity. The results obtained show clearly that these stresses are in direct relation not only with the thickness and properties of the FGM tube but also with the presence of the cavity.

Highlights

W ith industrial development, pressure vessels and tubes are widely used in reactor technology, chemical industries, marine engineering and aerospace
Kordkheili et al [8] and Safari et al [9] presented a solution by an analytical method for the mechanical behavior of a cylindrical structure in FGM, while Sharma et al [10] and You et al [11] consider in their analysis a purely elastic behavior on a spherical structure under internal pressure
A study based on finite element analysis was carried out to understand the influence of the position of a spherical cavity in a tubular FGM structure of type TiB/Ti subjected only to internal pressure

Summary

Introduction

W ith industrial development, pressure vessels and tubes are widely used in reactor technology, chemical industries, marine engineering and aerospace. Other research, using the finite element method, have analyzed the effect of porosity in the analysis of inter-facial stresses of FGM beams perfectly reinforced with a plate of porous materials with functional gradation, whereas Benferhat et al [38,39] studied the effect of shapes and the distribution of porosity on the bending behavior of a plate in FGM and developed a general model to predict the distribution of the interfacial shear stress and the normal stresses of the beam (FG) reinforced by porous FGM plates under mechanical loading They showed that the normal and shear stresses at the interface are influenced by the material parameters and that the inhomogeneities play an important role in the distribution of these interfacial stresses. We assume the presence of defects (cavity) in different positions in the FGM, the axial and radial stresses were evaluated under these different effects

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Conclusion