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elasto-plastic-analysis
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Elastoplastic Analysis of Rotating Disk with Damage
, M.Sc. Thesis Sharif University of Technology ; Asghari, Mohsen (Supervisor)
Abstract
In the present study, by considering the damage effects, the governing equations for elastoplastic behavior of a rotating disk are derived. Then several numerical solutions are presented for specific examples. First, by means of elastic strain energy functions along with the damage appearing in the literature and irreversible Thermodynamics laws, an analytical solution is generated for a rotating disk undergoing elastic deformations. For this purpose, the components of strain tensor are obtained in terms of the damage variable and the stress tensor components. Then, by employing the damage evolution relations mixed with the damage surface relation, damage variable is derived as a function of...
Wall thickness optimization of thick-walled spherical vessel using thermo-elasto-plastic concept
, Article International Journal of Pressure Vessels and Piping ; Volume 82, Issue 5 , 2005 , Pages 379-385 ; 03080161 (ISSN) ; Rezai Zarei, A ; Darijani, H ; Sharif University of Technology
2005
Abstract
A study of thick-walled spherical vessels under steady-state radial temperature gradients using elasto-plastic analysis is reported. By considering a maximum plastic radius and using the thermal autofrettage method for the strengthening mechanism, the optimum wall thickness of the vessel for a given temperature gradient across the vessel is obtained. Finally, in the case of thermal loading on a vessel, the effect of convective heat transfer on the optimum thickness is considered, and a general formula for the optimum thickness and design graphs for several different cases are presented. © 2004 Elsevier Ltd. All rights reserved
Elasto-Plastic Design of Thick-Walled FG Vessels under Pressure or Temperature Gradient Loadings
, M.Sc. Thesis Sharif University of Technology ; Kargarnovin, Mohammad Hossein (Supervisor)
Abstract
Nowadays functionally graded materials have many applications in various industries. One of these applications can be the manufacturing of thick-walled vessels. Thick-walled vessels under internal pressure and high temperatures gradient require materials with higher strength, like Functionally Graded Materials (FGM) and can be reinforced by some mechanical processes like autofrettage. In this process under certain loading some part of vessels enters into plastic zone and upon unloading some residual stresses will be generated. Moreover it is very important to find out the depth of this plastic zone, In addition, minimizing the stress distribution vs. depth of plastic zone under applied...
Investigation into the Effects of Using Various Thermal Insulators on the Behaviour of Structural Connections During Fire
, M.Sc. Thesis Sharif University of Technology ; Khonsari, Vahid (Supervisor)
Abstract
Steel is a non-combustible material, but at high temperatures, steel structures, due to their diminishing yield strength, undergo a considerable visco-plastic deflection, which results in a reduction in their load bearing capacity. Thus, to increase safety against fire must be considered as an important objective in the design and construction of steel structures. One of the safety measures which can be taken against fire is to increase the resistance of the structure against heat by using heat-resistant coatings. This decreases the rate of transfer of heat to the structure, and must include the ‘structural members’ and ‘structural joints’. Due to the role of structural connections in...
Application of FEM simulation of chip formation to stability analysis in orthogonal cutting process
, Article Journal of Manufacturing Processes ; Volume 14, Issue 3 , 2012 , Pages 188-194 ; 15266125 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
Elsevier
2012
Abstract
Models for chatter prediction in machining often use a mechanistic force model that calculate the force as the product of a material dependent cutting constant and chip area. However, in reality, the forces are the result of complex interaction between the tool and the chip, and are affected by many factors. The effects of these complex, and often nonlinear, factors on the machining dynamics may only be included in chatter prediction if the chip formation process is simulated concurrently with simulation of the machining dynamics. In this paper, finite element simulation of the chip formation process is combined with simulation of chatter dynamics and the inter-relationship between the chip...
The influence of fiber/matrix debonding on inelastic micro-mechanical behavior of cross-ply IMC composites
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 4 , 2010 , Pages 197-222 ; 9780791849187 (ISBN) ; Abedian, A ; Sharif University of Technology
2010
Abstract
In this study the effect of stress field on delamination and fiber/ matrix debonding in laminated composite panels is investigated from the micro-mechanical point of view by means of 3-D Finite Element Models. Specifically, the behavior of two-layer cross-ply symmetric laminates made up of SCS-6/Ti-24Al-11Nb Intermetallic Matrix Composite (IMC) during cooling from the processing temperature is studied. The results show that large plastic strains occur at the fiber/ matrix interface at the fiber end on the laminate free edge which may eventually extend to the interface of the layers of the laminate inflicting delamination damage. This phenomenon is more serious at the corner areas of the...
Design of spherical vessels under steady-state thermal loading using thermo-elasto-plastic concept
, Article International Journal of Pressure Vessels and Piping ; Volume 86, Issue 2-3 , 2009 , Pages 143-152 ; 03080161 (ISSN) ; Kargarnovin, M. H ; Naghdabadi, R ; Sharif University of Technology
2009
Abstract
Governing equilibrium equations of thick-walled spherical vessels made of material following linear strain hardening and subjected to a steady-state radial temperature gradient using elasto-plastic analysis are derived. By considering a maximum plastic radius and using the concept of thermal autofrettage for the strengthening mechanism, the optimum wall thickness of the vessel for a given temperature gradient across the wall thickness is obtained. Finally, in the case of thermal loading on a vessel, the effect of convective heat transfer on the optimum thickness is studied and a general formula for the optimum wall thickness and design graphs for several different cases are presented. © 2008...
FEM prediction of welding residual stresses and temperature fields in butt and T-welded joints
, Article Advanced Materials Research, 16 December 2011 through 18 December 2011 ; Volume 418-420 , December , 2012 , Pages 1486-1493 ; 10226680 (ISSN) ; 9783037853269 (ISBN) ; Hafezi, F ; Farrahi, H ; Sharif University of Technology
Abstract
Residual stresses resulted from localized non-uniform heating and subsequent cooling during welding processes enact an important role in the formation of cracks and welding distortions and have severe effect on performance of welded joints. The present research performs a three dimensional transient thermo Elasto-plastic analysis using finite element technique to simulate welding process. Welding simulation procedure is developed using the parametric design language of commercial code ANSYS for single pass T and butt welded joints. The procedure verified with predicted residual stress field found in literature to confirm the accuracy of the method. The material of the weld metal, HAZ and the...