Aref Mehditabar and Gholam H. Rahimi
This study aims to explain the characterization of cyclic behavior of a tube made of functionally graded material (FGM) under different combinations of internal pressure and…
Abstract
Purpose
This study aims to explain the characterization of cyclic behavior of a tube made of functionally graded material (FGM) under different combinations of internal pressure and cyclic through-thickness temperature gradients.
Design/methodology/approach
The normality rule, nonlinear kinematic hardening Chaboche model and Von Mises yield criterion were used to model the constitutive behavior of an FG tube in the incremental form. The material properties and hardening parameters of the Chaboche model vary according to the power-law function in the radial direction. The backward Euler integration scheme combined with return mapping algorithm which relies on the solution of a nonlinear equation performs the numerical procedure. The algorithm is implemented within the user subroutine UMAT in ABAQUS/standard.
Findings
The published works on FG components considering only the mechanical and physical properties as a function of spatial coordinate and nonlinear kinematic hardening parameters have not been considered to be changed continuously from one surface to another. Motivated by this, the present paper has deliberately been targeted to tackle this kind of problem to simulate the cyclic behavior of an FG tube as accurately as possible. In addition, to classify various behaviors the FG tube under cyclic thermomechanical loadings, Bree’s interaction diagram as an essential tool in designing of the FG pressure vessels in many engineering sectors is presented.
Originality/value
Provides a detailed description of the FG parameters of Chaboche kinematic hardening parameters in the adopted constitutive equations. In this paper, the significant effects of internal pressure values, kinematic hardening models and also FG inhomogeneity index related to the hardening rule parameters on plastic deformation of the FG tube are illustrated. Finally, the various cyclic behaviors of the FG tube under different combinations of thermomechanical loading are fully explored.
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Aref Mehditabar, Gholam H. Rahimi and Seyed Ebrahim Vahdat
The purpose of this paper is to investigate the characterizations of high energy thick-walled functionally graded (FG) cylinder containing Al-26%Cu fabricated by horizontal…
Abstract
Purpose
The purpose of this paper is to investigate the characterizations of high energy thick-walled functionally graded (FG) cylinder containing Al-26%Cu fabricated by horizontal centrifugal casting technique.
Design/methodology/approach
Field emission scanning electron microscopy in conjunction with image analyser software and energy dispersion spectroscopy is applied to measure the variations of constituent phase’s content and elemental ratios along the radial direction, respectively. Distributions of the FG properties are measured through hardness, CTE, E and σy along the radial direction to investigate the mechanical and physical properties corresponding to the variations in microstructure. In addition, the variations of wear rate along the thickness are evaluated through a series of dry sliding wear tests using the pin-on-disk wear machine. Moreover, scanning electron microscopy is employed to characterize the worn-out surfaces and morphology of wear debris in order to clarify the dominant operative wear mechanism.
Findings
Results showed that Al2Cu content gradually decreases from the inner wall containing 33.3 vol.% to outer wall containing 26.4 vol.% in the FG cylindrical shell. The elastic modulus and yield strength measured through compression tests reveal that these mechanical properties are limited up to certain value of Al2Cu. The obtained optimum value of Al2Cu content for studied Al-Al2Cu FG is almost 31 vol.%.
Originality/value
The obtained optimum value of Al2Cu content for studied Al-Al2Cu FG was almost 31 vol.%.
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Online feminist activism has opened a different path for ordinary Iranians who are not necessarily versed in post-revolutionary discourses on feminism and political activism, nor…
Abstract
Online feminist activism has opened a different path for ordinary Iranians who are not necessarily versed in post-revolutionary discourses on feminism and political activism, nor are familiar with the names and past achievements of Iranian women’s activist pioneers since the birth of the Islamic Republic in 1979. Social media has helped to tease apart government statecraft that continually touts and reemphasizes Islamic values, at the same time providing a platform for a feminist consciousness that more recently has passionately supported individual rights, especially the right to privacy. This chapter delves into this move toward a more individualized form of dissent, surveying the generational, ideological, and technological divides that have emerged among Iranian women’s activists following popular uprisings that have been happening domestically since 2009.