scholarly journals A Finite Element Approach for the Elastic-Plastic Behavior of a Steel Pipe Used to Transport Natural Gas

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Miltiades C. Elliotis
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Natural Gas ◽  
High Pressures ◽  
Circular Cross Section ◽  
Steel Pipe ◽  
Flow Rule ◽  
Plastic Behavior ◽  
Strain Component ◽  
Elastic Plastic

A finite element technique, with two-dimensional isoparametric elements, is developed, for the analysis of a steel pipe, with a circular cross-section. The pipe is installed above the ground and is used to transport natural gas at very high pressures. The material of the pipe is assumed to obey a bilinear elastic-plastic model. Double symmetry is considered when setting up the mathematical model problem and creating the finite element mesh. Step increments or decrements on the internal pressure are applied (cyclic loading). Yielding is detected by the Von Mises yield criterion. Also, a flow rule is employed to handle the plastic strain component. A four-point Gauss-Legendre quadrature is used to numerically perform all necessary integrations. Finally, the so-called “shakedown phenomenon” is studied when cyclic loading is applied after the commencement of plastic deformations on the pipe. Numerical results obtained by the method compare favorably with the analytic solution.

Effect of Defect on Elastic/Plastic and Creep Behavior of Bone: A Finite Element Study

2007 ◽  
Author(s):  
A. Ajdari ◽  
P. K. Canavan ◽  
H. Nayeb-Hashemi ◽  
G. Warner
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Trabecular Bone ◽  
Fatigue Loading ◽  
Dimensional Structure ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Local Bone ◽  
Osteoporotic Vertebral Fractures

Three-dimensional structure of trabecular bone can be modeled by 2D or 3D Voronoi structure. The effect of missing cell walls on the mechanical properties of 2D honeycombs is a first step towards understanding the effect of local bone resorption due to osteoporosis. In patients with osteoporosis, bone mass is lost first by thinning and then by resorption of the trabeculae [1]. Furthermore, creep response is important to analyze in cellular solids when the temperature is high relative to the melting temperature. For trabecular bone, as body temperature (38 °C) is close to the denaturation temperature of collagen (52 °C), trabecular bone creeps [1]. Over the half of the osteoporotic vertebral fractures that occur in the elderly, are the result of the creep and fatigue loading associated with the activities of daily living [2]. The objective of this work is to understand the effect of missing walls and filled cells on elastic-plastic behavior of both regular hexagonal and non-periodic Voronoi structures using finite element analysis. The results show that the missing walls have a significant effect on overall elastic properties of the cellular structure. For both regular hexagonal and Voronoi materials, the yield strength of the structure decreased by more than 60% by introducing 10% missing walls. In contrast, the results indicate that filled cells have much less effect on the mechanical properties of both regular hexagonal and Voronoi materials.

Computation of Ratchet Limits for Structures Subjected to Cyclic Loading and Temperature

2002 ◽  
Author(s):  
A. R. S. Ponter ◽  
H. Chen ◽  
M. Habibullah
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Mechanical Loading ◽  
Limit Theorems ◽  
Thermal Loading ◽  
Loading History ◽  
Cyclic Thermal Loading ◽  
Elastic Plastic ◽  
Plastic Structure ◽  
Shakedown Limit

The paper discusses methods of evaluating the ratchet limit for an elastic/plastic structure subjected to cyclic thermal and mechanical loading. A recently developed minimization theorems by Ponter and Chen [2] provides a generalization of the shakedown limit theorems for histories of load in excess of shakedown. This allows the development of programming methods that locate the ratchet boundary in excess of shakedown. Examples of applications are provided including the performance of a cracked body subjected to cyclic thermal loading. Finally, the theory is used to discuss Kalnins’ [4] proposal that short cut finite element solutions may be used to assess whether a particular loading history lies within a ratchet limit.

A Simplified Analysis Method for Complex Piping Systems in Elastic-Plastic-Creep Range

1985 ◽  
Vol 107 (2) ◽  
pp. 148-156
Author(s):  
O. Watanabe ◽  
H. Ohtsubo
Keyword(s):  
Finite Element ◽  
Present Method ◽  
Constitutive Relations ◽  
Plastic Behavior ◽  
Piping System ◽  
Curved Beams ◽  
Elastic Plastic ◽  
Piping Systems ◽  
Creep Deformations ◽  
Plastic Creep

The present paper describes a simplified finite element method for analysis of behavior of complex piping systems under elevated temperature. Elastic-plastic-creep deformations of a piping system under a combined moment loading can be analyzed by the present method. The system is idealized by straight and curved beams, and derivation of the finite element equation is based on the force method. The unified constitutive relations are used for creep and plastic behavior, where plastic deformation is treated as a limiting case of creep. The numerical results are compared with previous experimental ones, which verifies the validity of the proposed method. Elastic follow-up problem of a piping system of actually complex configuration is also solved by the present method.

Seismic Analysis of Soil Nailed Wall Using Finite Element Method

2012 ◽  
Vol 535-537 ◽  
pp. 2027-2031 ◽  
Author(s):  
Jian Chun Wu ◽  
Rong Shi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Seismic Analysis ◽  
Retaining Wall ◽  
Plastic Behavior ◽  
Soil Nailing ◽  
Nonlinear Fem ◽  
Elastic Plastic ◽  
Flexible Retaining Wall ◽  
Element Method

Using dynamic elastic-plastic finite element method, on the base of works together and interaction between loess and flexible retaining wall, 3-D nonlinear FEM (ADINA) is used to analyze and discussed the dynamic response of slope protected by soil nailing retaining wall under the EL-Centro and man-made Lanzhou accelerogram. A model that is capable of simulating the nonlinear static and dynamic elastic-plastic behavior of soil is used to model the soil, and a bilinear elastic-plastic model that has hardening behavior is used to model the soil nailing. Friction-element is employed to describe the soil-structure interaction behavior.The results show that the method is safe and credible. The results of the FEM dynamic analysis can be a useful reference for engineers of the design and construction of the soil nailed wall.

A Simplified Technique for Shakedown Load Determination of a 90 Degree Pipe Bend Subjected to Constant Internal Pressure and Cyclic In-Plane Bending

2005 ◽  
Author(s):  
Hany F. Abdalla ◽  
Maher Y. A. Younan ◽  
Mohammed M. Megahed
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Internal Pressure ◽  
High Heat ◽  
Heat Fluxes ◽  
Elastic Analysis ◽  
Pipe Bend ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Plane Bending

In this paper a simple technique is presented to determine the shakedown load of a 90 degree pipe bend subjected to constant internal pressure and cyclic in-plane bending using the finite element method. Through the proposed technique, the shakedown load is determined without performing time consuming cyclic loading simulations or conventional iterative elastic techniques. Instead, the shakedown load is determined through performing only two analyses namely; an elastic analysis and an elastic-plastic analysis. By extracting the results of the two analyses, the shakedown load is determined through the calculation of the residual stresses developed in the pipe bend. In the elastic analysis, performed only once and stored, an in-plane closing moment is applied preserving structure stresses within the material elastic range. In the elastic-plastic analysis, a constant internal pressure, below the pressure to cause yielding, is applied in addition to an increasing moment magnitude that causes the material yield strength to be exceeded. For verification purposes, the results of the simplified technique are compared to the results of full cyclic loading finite element simulations where the pipe bend is subjected to constant internal pressure and cyclic in-plane closing moment loading. In order to have confidence in the proposed technique, it is applied beforehand on the Bree cylinder [1] subjected to constant internal pressure and cyclic high heat fluxes across its wall. The results of the proposed technique showed very good correlation with the, analytically determined, Bree diagram of the cylinder.

scholarly journals Identification of elastic-plastic behavior in AHSS using the isotropic hardening model by the finite element method and EBSD

2019 ◽  
Vol 6 (5) ◽  
pp. 649-658
Author(s):  
Érika Aparecida da Silva ◽  
Marcelo dos Santos Pereira ◽  
Jean Pierre Faye ◽  
Rosinei Batista Ribeiro ◽  
Nilo Antonio de Sousa Sampaio ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Isotropic Hardening ◽  
Plastic Behavior ◽  
The Finite Element Method ◽  
Hardening Model ◽  
Elastic Plastic ◽  
Element Method
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