Modeling and Simulation of Wave Propagation Based on Atomistic Field Theory

2010 ◽  
Vol 78 (2) ◽  
Author(s):  
Xianqiao Wang ◽  
James D. Lee ◽  
Qian Deng
Keyword(s):  
Field Theory ◽  
Finite Element ◽  
Wave Propagation ◽  
Modeling And Simulation ◽  
Material Behavior ◽  
Dynamics Simulation ◽  
Wave Reflections ◽  
Element Analysis ◽  
Continuum Region ◽  
Atomistic Region

Motivated by the need for a more efficient simulation of material behavior at both larger length scale and longer time scale than direct molecular dynamics simulation, an atomistic field theory (AFT) for modeling and simulation of multiphase material systems has been developed. Atomistic formulation of the multiscale field theory and its corresponding finite element implementation are briefly introduced. By virtue of finite element analysis of classical continuum mechanics, we show the existing phenomena of spurious wave reflections at the interfaces between regions with different mesh sizes. AFT is employed to investigate the wave propagation in magnesium oxide from the atomistic region to the continuum region without any special numerical treatment. Unlike some other atomistic/continuum computational methods, AFT has demonstrated the capability to display both acoustic and optic types of wave motion. Numerical results show that AFT has the capability to significantly reduce the wave reflections at the interface. This work provides a more fundamental understanding of wave reflections at the atomistic/continuum interface.

Finite Element Analysis of Casing Material Behavior in Steam Injection Well Operations

2015 ◽  
Vol 799-800 ◽  
pp. 196-200
Author(s):  
Abhilash M. Bharadwaj ◽  
Sonny Irawan ◽  
Saravanan Karuppanan ◽  
Mohamad Zaki bin Abdullah ◽  
Ismail bin Mohd Saaid
Keyword(s):  
Finite Element ◽  
Oil Recovery ◽  
Thermal Stresses ◽  
Oil And Gas ◽  
Extreme Temperature ◽  
Injection Pressure ◽  
Oil And Gas Industry ◽  
Steam Injection ◽  
Material Behavior ◽  
Element Analysis

Casing design is one of the most important parts of the well planning in the oil and gas industry. Various factors affecting the casing material needs to be considered by the drilling engineers. Wells partaking in thermal oil recovery processes undergo extreme temperature variation and this induces high thermal stresses in the casings. Therefore, forecasting the material behavior and checking for failure mechanisms becomes highly important. This paper uses Finite Element Methods to analyze the behavior two of the frequently used materials for casing - J55 and L80 steels. Modeling the casing and application of boundary conditions are performed through Ansys Workbench. Effect of steam injection pressure and temperature on the materials is presented in this work, indicating the possibilities of failure during heating cycle. The change in diameter of the casing body due to axial restriction is also presented. This paper aims to draw special attention towards the casing design in high temperature conditions of the well.

Creep Life Simulation and Assessment of High Temperature Piping Systems and Components

2012 ◽  
Author(s):  
Brian Rose ◽  
James Widrig
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Temperature ◽  
Creep Behavior ◽  
Material Behavior ◽  
Piping System ◽  
Remaining Life ◽  
Creep Life ◽  
Element Analysis ◽  
Piping Systems

High temperature piping systems and associated components, elbows and bellows in particular, are vulnerable to damage from creep. The creep behavior of the system is simulated using finite element analysis (FEA). Material behavior and damage is characterized using the MPC Omega law, which captures creep embrittlement. Elbow elements provide rapid yet accurate modeling of pinching of piping, which consumes a major portion of the creep life. The simulation is used to estimate the remaining life of the piping system, evaluate the adequacy of existing bellows and spring can supports and explore remediation options.

Nonlinear Finite Element Analysis for Thermoplastic Pipes

1998 ◽  
Vol 1624 (1) ◽  
pp. 225-230 ◽  
Author(s):  
Chuntao Zhang ◽  
Ian D. Moore
Keyword(s):  
Finite Element ◽  
Geometrical Nonlinearity ◽  
Constitutive Models ◽  
Material Behavior ◽  
Pipe Material ◽  
Limit States ◽  
Element Analysis ◽  
Finite Element Program ◽  
Highly Nonlinear ◽  
Nonlinear Constitutive Models

Thermoplastic pipes are being used increasingly for water supply lines, storm sewers, and leachate collection systems in landfills. To facilitate limit states design for buried polymer pipes, nonlinear constitutive models have recently been developed to characterize the highly nonlinear and time-dependent material behavior of high-density polyethylene (HDPE). These models have been implemented in a finite element program to permit structural analysis for buried HDPE pipes and to provide information regarding performance limits of the structures. Predictions of HDPE pipe response under parallel plate loading and hoop compression in a soil cell are reported and compared with pipe response measured in laboratory tests. Effects on the structural performance of pipe material nonlinearity, geometrical nonlinearity, and backfill soil properties were investigated. Good correlations were found between the finite element predictions and the experimental measurements. The models can be used to predict pipe response under many different load histories (not just relaxation or creep). Work is ongoing to develop nonlinear constitutive models for polyvinylchloride and polypropylene to extend the predictive capability of the finite element model to these materials.

Dynamics Simulation and Analysis of Planetary Reducer

2013 ◽  
Vol 765-767 ◽  
pp. 422-426 ◽  
Author(s):  
Ling Ling ◽  
Yuan Yuan Yi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Electric Vehicle ◽  
Coupling Model ◽  
Dynamics Simulation ◽  
Element Analysis ◽  
Flexible Coupling ◽  
Object Of Study ◽  
Planet Carrier

Taking a planetary reducer in an electric vehicle as the object of study, a rigid-flexible coupling model was established to perform the dynamics simulation. The variational regularities of the meshing forces, output speed and acting forces of bearings were obtained, and then a finite element analysis of the planet carrier was carried out. This method can not only solve the problem of the boundary conditions of planet carrier which are difficult to define in finite element analysis, but also improve the accuracy of analysis results when the influence of carrier flexibility on the whole system is considered in dynamics simulation, which lays the foundation for further research on reducers.

Finite Element Analysis of a Locked Bolt With an Initial Crack

2009 ◽  
Author(s):  
Jean Paul Kabche ◽  
Mauri´cio Rangel Pacheco ◽  
Ivan Thesi ◽  
Luiz Carlos Largura
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Operating Conditions ◽  
Material Behavior ◽  
Isotropic Hardening ◽  
Stress Concentrations ◽  
Engineering Structures ◽  
Element Analysis ◽  
Micro Cracks ◽  
Non Linear

Bolted connections are largely employed in various types of engineering structures to transfer loads from one member to another. In particular, the off-shore industry has made extensive use of these connections, predominantly at the sub-sea level. In spite of their advantages, bolted joints are critical regions and may become sources of structural weakness due to large stress concentrations. Under severe operating conditions, micro-cracks can develop in the bolt, creating regions of elevated stress which may significantly reduce the integrity of the connection and ultimately lead to failure. This paper presents the three-dimensional finite element analysis of a steel locked bolt assembly aimed to assess the effect of micro-cracks on the structural integrity of the assembly using the commercial finite element package ANSYS. Non-linear contact between the bolt and nut threads is considered, where frictional sliding between components is allowed. A bi-linear isotropic hardening model is used to account for non-linear material behavior. The assembly is loaded by applying a pre-load of fifty percent of the yield stress of the material, according to the API-6A Norm. Two geometric models are investigated: a healthy locked bolt assembly with no initial cracks; and a damaged model, where a circular crack is introduced at the root of the bolt threads. The effect of the crack size is studied by modeling the crack with three different radius sizes. The J-Integral fracture mechanics methodology was used to study the stress concentrations in the damaged model.

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