Crystal Plasticity Analysis of Thermal Deformation and Dislocation Accumulation in Gaas/Si Patterned Structure

1991 ◽  
Vol 226 ◽  
Author(s):  
Tetsuya Ohashi ◽  
Naoyuki Honda
Keyword(s):  
Thermal Deformation ◽  
Three Dimensional ◽  
Film Deposition ◽  
Shear Stresses ◽  
Slip Systems ◽  
Quantitative Expression ◽  
Plastic Slip ◽  
Dislocation Densities ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

AbstractPlastic slip deformation in patterned.GaAs films on Si substrate during cooling from film deposition temperature are numerically simulated under a continuum mechanics approximation. The plastic slip is assumed to take place on (111) <110> slip systems and activation condition of the slip systems is given by the Schmid's law. The critical resolved shear stresses for the activation of slip systems are expressed as a function of accumulated dislocation densities, which are evaluated by models for their movement and interaction. A three dimensional finite element computer program is developed, in which strain hardening behaviour is given a quantitative expression by the models for dislocations. Results of the simulation reveal process of plastic slip and dislocation accumulation in GaAs film. Residual stress evaluated by the simulation agreed well with results obtained by photo-luminescent experiments.

Case Study of the Effect of Generator Retaining Ring Shrink Fit on Rotor Tooth Top Cracking

2011 ◽  
Author(s):  
Daniel T. Peters ◽  
Kevin M. Haley
Keyword(s):  
Three Dimensional ◽  
Cyclic Fatigue ◽  
Shear Stresses ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Retaining Ring ◽  
Rotor Tooth ◽  
Three Dimensional Finite Element ◽  
Shrink Fit

A significant concern in generator operation is cracking in the tops of the rotor teeth due to cyclic fatigue. The shrink fit of a retaining ring over the rotor end induces compressive stresses in the rotor to contain the entire assembly and reduce shear stresses in the rotor teeth during operation. This paper is a case study of the effect of this shrink fit on fatigue life using three dimensional finite element analysis with nonlinear contact to simulate the interaction between the rotor, wedges and retaining ring. For the analysis, consideration was made for both operational and shut down loading to determine the stress state in both conditions for application in fatigue analysis. Overspeed conditions were not considered for this analysis.

Study of Parameter Effects on Residual Stresses and Thermal Deformation of Brazed Plate-Fin Structure Using Finite Element Method

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Hu Chen ◽  
Jian-Ming Gong ◽  
Shan-Tung Tu ◽  
Lu-Yang Geng
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Thermal Deformation ◽  
Three Dimensional ◽  
Negative Effects ◽  
Element Analysis ◽  
Vacuum Brazing ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Clamping Pressure

The brazed plate-fin structure is the key component of a compact plate-fin heat exchanger. The residual stresses and thermal deformation induced by vacuum brazing may bring negative effects on the quality and the life of the plate-fin structure. Thus, it is important to optimize the brazing parameters in order to minimize such effects. This paper presents a three-dimensional finite element analysis for determining the residual stresses and thermal deformation of a three layered stainless steel plate-fin structure fabricated by nickel-based brazing. The features of residual stresses and thermal deformation distribution are discussed. The effects of three major brazing parameters including brazing temperature, clamping pressure load, and filler metal on the residual stresses and thermal deformation are investigated, respectively.

Finite Element Study of Factor Effects on Residual Stresses and Thermal Deformation of Brazed Plate-Fin Structure

2007 ◽  
Vol 353-358 ◽  
pp. 473-476
Author(s):  
Hu Chen ◽  
Jian Ming Gong ◽  
Shan Tung Tu ◽  
Lu Yang Geng
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Thermal Deformation ◽  
Three Dimensional ◽  
Negative Effects ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Major Factors ◽  
Three Dimensional Finite Element ◽  
Clamping Pressure

The brazed plate-fin structure is the key component of a compact plate-fin heat exchanger (PFHE). The thermal deformation and residual stresses induced by vacuum brazing may bring negative effects on the quality and the life of the plate-fin structure. Thus it is important to optimize the brazing parameters in order to minimize such effects. This paper presents a three-dimensional finite element analysis for determining the thermal deformation and residual stresses of a three layers of stainless steel plate-fin structure fabricated by nickel-based brazing. The feature of thermal deformation and residual stresses distribution are discussed. The effects of three major factors including brazing temperature, clamping pressure and filler metal on the thermal deformation and residual stresses are investigated respectively.

Bending analysis of soft core sandwich plates with embedded shape memory alloy wires using three-dimensional finite element method

2012 ◽  
Vol 226 (3) ◽  
pp. 186-202 ◽  
Author(s):  
Mohammad M Kheirikhah ◽  
Mahdi Khadem ◽  
Peyman Farahpour
Keyword(s):  
Finite Element Method ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Sandwich Plate ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Sandwich Plates ◽  
Dimensional Finite Element ◽  
Transverse Shear Stresses ◽  
Three Dimensional Finite Element

In this article, bending behavior of the sandwich plates with embedded shape memory alloy wires in their face sheets is studied. Three-dimensional finite element method is used for constructing and analyzing the sandwich plates with flexible core and two stiff face sheets. Some important points such as continuity conditions of the displacements, satisfaction of inter-laminar transverse shear stresses, conditions of zero transverse shear stresses on the upper and lower surfaces and in-plane and transverse flexibility of the soft core are considered for the accurate modeling of the sandwich plate. Solutions for bending analysis of shape memory alloy wire-reinforced sandwich plates under various transverse loads are presented and the effects of plate dimensions, shape memory alloy wires diameter, boundary conditions and shape memory alloy wires embedding positions are studied. Comparison of the present results in special case with those of the three-dimensional theory of elasticity and some plate theories confirms the accuracy of the proposed model. According to the obtained numerical results, the local behavior of the sandwich plate in bending against various loading conditions was significantly improved by employing the shape memory alloy wires in the face sheets.

Evaluation of Flexural Displacement in Piezoelectric Actuators Considering the Thermal Deformation

2007 ◽  
Vol 345-346 ◽  
pp. 1141-1144
Author(s):  
Sung Choong Woo ◽  
Nam Seo Goo
Keyword(s):  
Thermal Deformation ◽  
Temperature Drop ◽  
Three Dimensional ◽  
Piezoelectric Actuators ◽  
Piezoelectric Composite ◽  
Element Simulation ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Plate Type ◽  
Pzt Ceramic

In this article, the flexural displacement of plate-type piezoelectric composite actuators (PCA) with various lay-up configurations has been evaluated considering the thermal deformations induced by a temperature drop using a three-dimensional finite element simulation. The results reveal that the flexural displacement of PCA subjected to electrical loadings is significantly affected by their lay-up configurations, the thickness of constituent PZT ceramic and applied boundary conditions, which is associated with the location of the neutral plane by moment equilibrium and the bending stiffness of PCA. For the displacement performance of PCA, an adequate choice of layup configuration together with the proper thickness of PZT ceramic is required.

scholarly journals THE PROJECTED EFFECT FROM ACCEPTANCE OF CONSTRUCTIVE SOLUTIONS TO ENSURE THE RELIABILITY OF AN INDUSTRIAL FACILITY

Vestnik MGSU ◽  
2015 ◽  
pp. 80-89
Author(s):  
Robert Alekseevich Turusov ◽  
Hamed Memarianfard
Keyword(s):  
Three Dimensional ◽  
Outer Radius ◽  
Shear Stresses ◽  
Element Analysis ◽  
Thermal Residual Stresses ◽  
Filament Wound ◽  
Inner Radius ◽  
Dimensional Finite Element ◽  
Interlaminar Shear ◽  
Three Dimensional Finite Element

In this paper a three-dimensional finite element analysis employed to predict thermal residual stresses field which arises during the cooling stage at the free edges of a thick walled filament wound cylinder with cross-ply lamination. The inner radius of composite is 50 mm and outer radius is 75 mm and the thickness of steel mandrel is 3 mm. The results showed that the radial stresses near the free ends of the cylinder increased two times compared to radial stresses in the middle of the cylinder and interlaminar shear stresses exceeded 6 MPa close to the free edges.Thus, a two-dimensional stress analysis does not fully reflect the complex state of stress of thick-walled cross-ply filament wound cylinders.

Effect of the Residual Stresses at the Stem–Cement Interface on the Mechanical Behaviour of Cemented Hip Femoral Prosthesis

2015 ◽  
Vol 17 ◽  
pp. 54-63 ◽  
Author(s):  
M.M. Bouziane ◽  
A. Moulgada ◽  
N. Djebbara ◽  
A. Sahli ◽  
Bel Abbès Bachir Bouiadjra ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Exothermic Reaction ◽  
Three Dimensional ◽  
Thermal Shrinkage ◽  
Shear Stresses ◽  
Cement Interface ◽  
Linear Elastic ◽  
Dimensional Finite Element ◽  
Von Mises ◽  
Three Dimensional Finite Element

In orthopaedic surgery and particularly in the total hip arthroplasty, the stem fixation is performed in general using a surgical cement which consists essentially of polymer polymethyl-methacrylate (PMMA). During polymerisation of PMMA, residual stresses caused by volumetric and thermal shrinkage (exothermic reaction) are generated in the bulk cement. In this study, the three-dimensional finite element method is used to analyze the distribution stresses in the bone cement. Linear elastic analysis is adapted; von Mises, normal and shear stresses are the criterions that are of concern. The results showed that the inclusion of the residual stresses at the interface stem–cement increase the von Mises and the normal stresses in the different sides of the cement compared to the case without residual stresses.

AN EFFICIENT PSEUDO THREE-DIMENSIONAL FINITE ELEMENT MODEL: PRESENTATION AND ANALYSIS OF TWO SOIL/FOUNDATION INTERACTION PROBLEMS

2005 ◽  
Vol 02 (02) ◽  
pp. 231-253 ◽  
Author(s):  
DJ. AMAR BOUZID ◽  
P. A. VERMEER ◽  
B. TILIOUINE ◽  
M. MIR
Keyword(s):  
Finite Element ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Element Model ◽  
Combined Loading ◽  
Shear Stresses ◽  
Fe Method ◽  
Dimensional Finite Element ◽  
Soil Foundation ◽  
Three Dimensional Finite Element

A pseudo-three-dimensional numerical model has been developed for the analysis of full 3D soil problems under combined loading. The procedure called Vertical Slices Model takes advantage of finite element (FE) 2D numerical solutions in plane stress for building approximate 3D solutions by replacing the inter-slice interactions by fictitious body forces. Continuum slices are successively analyzed by the combination of the explicit 2D finite element (FE) method and finite difference (FD) method in iterative process. The three-dimensional aspect of the considered problem is preserved by satisfying the continuity of shear stresses developed at the inter-slices. The theory of the vertical slices model is developed first, and then encoded in a Fortran computer program. Next, the prediction capabilities of this program are illustrated with two classical geotechnical applications, namely; the laterally and the axially loaded single piles embedded in homogeneous and non-homogeneous elastic soils. Although approximate, the model proved its ability to capture the behavior of the two boundary value problems. Then, in terms of stiffness factors the approach is used to predict the behavior of an embedded rigid square footing and a pile under combined loading in a half-space where the stiffness shows a power law variation with depth.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

Sign in / Sign up

Export Citation Format

Share Document