Elastic-plastic

دسترسی آزاد مقاله

1 - Numerical Analysis of the Effect of External Circumferential Cracks in Transition Thickness Zone of Pressurized Pipes Using XFEM – Elastic-Plastic Behavior
H Salmi Kh EL Had H EL Bhilat A Hachim

10.22034/jsm.2019.1882104.1511

The elastic-plastic behavior of the material is considered to analyze the effect of an external circumferential crack on a pipe with thickness transitionand double slopes. Using the extended finite element method (XFEM), the J-integral of 3D cracks were investigated and چکیده کامل

The elastic-plastic behavior of the material is considered to analyze the effect of an external circumferential crack on a pipe with thickness transitionand double slopes. Using the extended finite element method (XFEM), the J-integral of 3D cracks were investigated and compared between straight pipes and pipes with thickness transition and different slopes. Considering internal pressure, this work highlighted the investigation of a 3D crack problem ina thickness transition pipe with a double slope,In the extended finite element method (XFEM), the level sets and the enrichment zone were defined. A crack is easily modeled by enrichment functions. The comparison between the values of the J-integral showed that the pipe containing thickness transition with double slopes is more sensitive to the considered cracks, more precisely, the parameters of the first thickness transition have more influence on the variation of J-integral than the parameters of the second thickness transition. The decreasing of the angle of the slopes and the increase of the ratio of the thicknesses is one effective method of reducing the J-integral. پرونده مقاله

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2 - Implementing the New First and Second Differentiation of a General Yield Surface in Explicit and Implicit Rate-Independent Plasticity
F Moayyedian M Kadkhodayan

In the current research with novel first and second differentiations of a yield function, Euler forward along with Euler backward with its consistent elastic-plastic modulus are newly implemented in finite element program in rate-independent plasticity. An elastic-plast چکیده کامل

In the current research with novel first and second differentiations of a yield function, Euler forward along with Euler backward with its consistent elastic-plastic modulus are newly implemented in finite element program in rate-independent plasticity. An elastic-plastic internally pressurized thick walled cylinder is analyzed with four famous criteria including both pressure dependent and independent. The obtained results are in good agreement with experimental results. The consistent/continuum elastic-plastic moduli for Euler backward method are also investigated. پرونده مقاله

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3 - Mechanical Stresses in a Linear Plastic FGM Hollow and Solid Rotational Disk
M Jabbari A Hatefkia M Shokouhfar

In this paper, an analytical solution for computing the plastic & linear plastic stresses and critical angular velocity in a FGM hollow & solid rotating disk is developed. It has been assumed that the modulus of elasticity and yield strength were varying through چکیده کامل

In this paper, an analytical solution for computing the plastic & linear plastic stresses and critical angular velocity in a FGM hollow & solid rotating disk is developed. It has been assumed that the modulus of elasticity and yield strength were varying through thickness of the FGM material according to a power law relationship. The Poisson's ratio were considered constant throughout the thickness. In the analysis presented here the effect of non-homogeneity in FGM rotating disk was implemented by choosing a dimensionless parameter, named m, which could be assigned an arbitrary value affecting the stresses in the rotating disk. Distribution of stresses in radial and circumferential directions for FGM rotating disk under the influence of angular velocity were obtained. Graphs of variations of stress, critical angular velocity versus radius of the rotating disk were plotted. The direct method is used to solve the Navier equations. پرونده مقاله

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4 - Elastic-Plastic Transition of Pressurized Functionally Graded Orthotropic Cylinder using Seth’s Transition Theory
S Sharma R Panchal

In this paper the radial deformation and the corresponding stresses in a functionally graded orthotropic hollow cylinder with the variation in thickness and density according to power law and rotating about its axis under pressure is investigated by using Seth's transit چکیده کامل

In this paper the radial deformation and the corresponding stresses in a functionally graded orthotropic hollow cylinder with the variation in thickness and density according to power law and rotating about its axis under pressure is investigated by using Seth's transition theory. The material of the cylinder is assumed to be non-homogeneous and orthotropic. This theory helps to achieve better agreement between experimental and theoretical results. Results has been mentioned analytically and numerically. From the analysis, it has been concluded that cylinder made up of orthotropic material whose thickness increases radially and density decreases radially is on the safer side of the design as circumferential stresses are high for cylinder made up of isotropic material as compared to orthotropic material. This paper is based on elastic-plastic behavior which plays important role in practical design of structures for safety factor. پرونده مقاله

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5 - Mechanical Stresses in a Linear Plastic FGM Hollow Cylinder Due to Non-Axisymmetric Loads
M Shokouhfar M Jabbari

In this paper, an analytical solution for computing the linear plastic stresses and critical pressure in a FGM hollow cylinder under the internal pressure due to non-Axisymmetric Loads is developed. It has been assumed that the modulus of elasticity was varying through چکیده کامل

In this paper, an analytical solution for computing the linear plastic stresses and critical pressure in a FGM hollow cylinder under the internal pressure due to non-Axisymmetric Loads is developed. It has been assumed that the modulus of elasticity was varying through thickness of the FGM material according to a power law relationship. The Poisson's ratio was considered constant throughout the thickness. The general form of mechanical boundary conditions is considered on the inside surfaces. In the analysis presented here the effect of non-homogeneity in FGM cylinder was implemented by choosing a dimensionless parameter, named m, which could be assigned an arbitrary value affecting the stresses in the cylinder. Distribution of stresses in radial, circumferential and shear directions for FGM cylinders under the influence of internal pressure were obtained. Graphs of variations of stress versus radius of the cylinder were plotted. The direct method is used to solve the Navier equations. پرونده مقاله

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6 - Investigation of Failure Mechanism in Earth Dam upon Triggered Liquefaction
Farzad Peyman

The behavior of the earth-dam body as a soil structure made of cohesive soil in the core and non-cohesive soil as the core supports, including water interaction upstream through earthquake upon multi-line constitutive equations, is the aim of this paper. A multi-plane m چکیده کامل

The behavior of the earth-dam body as a soil structure made of cohesive soil in the core and non-cohesive soil as the core supports, including water interaction upstream through earthquake upon multi-line constitutive equations, is the aim of this paper. A multi-plane mechanism-based approach is successfully employed for assigning post-liquefaction displacement of earth-dam structures. This approach is derived from total stress procedures with two major advantages:1) the triggering and post-liquefaction responses have been multi-lined into one analysis.2) the modeling of post-liquefaction element behavior is greatly improved.To sum up, a multi-plane-based framework is employed. The strength effects on integrated sampling planes and the resultant of this simulated multi-lined behavior are implemented for each finite element gauss point. This multi-plane-based model can also predict the effects of induced and inherent anisotropy plus the rotation of principal stress/strain axes through the plastic behavior of both cohesive and non-cohesive soils.The approach is presented through the simulation of the case history as the response of the lower San Fernando dam to the 1971 San Fernando earthquake. The magnitude and pattern of the predicted displacements are shown to be in good agreement with the measured values پرونده مقاله

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7 - Load Controlled Fatigue of AZ31B
E. کلاته مولایی ح. جاهد

With the expanding demand on application of magnesium alloys in automotive and aerospace industries, robust methods in fatigue characterization of commercially available magnesium alloys with high specific strength is anticipated. In this paper, rotating bending load co چکیده کامل

With the expanding demand on application of magnesium alloys in automotive and aerospace industries, robust methods in fatigue characterization of commercially available magnesium alloys with high specific strength is anticipated. In this paper, rotating bending load controlled tests has been studied on specimens machined from an extrusion piece of AZ31B. Due to asymmetric and anisotropic behavior of AZ31B, methods of transferring the load controlled results into stress-life results are lacking. Using the approach of variable material property (VMP), the load-stress relation in fully reversed test is derived. To apply the proposed method to AZ31B, the cyclic behavior of the material is required. Fully reversed step-loading of AZ31B over a wide range of strain amplitude was carried out on a servo hydraulic fatigue rig and was reported in the literature. The stabilized cyclic behavior at half-life was obtained for different load levels. Also, the cyclic tension and the cyclic compression curves were obtained. Using the proposed load-stress model and the actual cyclic behavior of AZ31B, an elastic-plastic solution over the whole domain of cross section was obtained. An energy based fatigue model was then employed to predict the life. The predicted and experimental lives agree well. The proposed method is recom-mended for correlating the load controlled test with stress and/or strain controlled tests. پرونده مقاله

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8 - Stabilized crack-opening stresses as a function of R-ratios and stress levels
Rahi Chermahini Majid Jabbari

An elastic-perfectly plastic middle crack tension aluminum 2024-T3 alloy was used under plane stress, plane strain and 3D analysis to determine stabilized crack-opening stresses for different R-ratios and stress levels. The stabilized crack-opening stresses of a 3D anal چکیده کامل

An elastic-perfectly plastic middle crack tension aluminum 2024-T3 alloy was used under plane stress, plane strain and 3D analysis to determine stabilized crack-opening stresses for different R-ratios and stress levels. The stabilized crack-opening stresses of a 3D analysis locate between those values of plane stress and plane strain conditions. Using the above strategy, one can determine crack-opening stresses for any desired thickness value using interpolating scheme. Two and three dimensional programs were developed based on small strain elasticity theory incorporating linear strain isoparametric elements. The plasticity part of the analysis uses initial stress approach. The crack was extended one element size as the applied load reached the maximum value of each load cycle. Crack opening and closure stresses of nodes on the crack surface plane after some cyclic crack extensions are demonstrated. Based on the obtained results, for the three-dimensional finite-element analysis, the calculated stabilized crack opening stresses always locate between those of plane stress and plane strain conditions. پرونده مقاله

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