Multinode Unsteady Surface Element Method With Application to Contact Conductance Problem

1986 ◽  
Vol 108 (2) ◽  
pp. 257-263 ◽  
Author(s):  
B. Litkouhi ◽  
J. V. Beck
Keyword(s):  
Numerical Technique ◽  
Three Dimensional ◽  
The Other ◽  
Surface Element ◽  
Variable Boundary ◽  
Transient Problems ◽  
Different Temperatures ◽  
Perfect Contact ◽  
Transfer Problems ◽  
Element Method

The unsteady surface element method is a powerful numerical technique for solution of linear transient two- and three-dimensional heat transfer problems. Its development originated with the need of solving certain transient problems for which similar or dissimilar bodies are attached one to the other over a part of their surface boundaries. In this paper a multinode unsteady surface element (MUSE) method for two arbitrary geometries contacting over part of their surface boundaries is developed and formulated. The method starts with Duhamel’s integral (for arbitrary time and space variable boundary conditions) which is then approximated numerically in a piecewise manner over time and the boundaries of interest. To demonstrate the capability of the method, it is applied to the problem of two semi-infinite bodies initially at two different temperatures suddenly brought into perfect contact over a small circular region. The results show excellent agreement between the MUSE solution and the other existing solutions.

Three-Dimensional Numerical Analysis of a Potential Rock Avalanche by Discrete Element Method

2020 ◽  
Vol 12 (2) ◽  
pp. 225-231
Author(s):  
Chuan Zhao ◽  
Linlin Jiang ◽  
Xiaopeng Li ◽  
Xiangyu Guo ◽  
Xiang Xiao
Keyword(s):  
Discrete Element Method ◽  
Average Velocity ◽  
Three Dimensional ◽  
Rock Avalanche ◽  
Discrete Element ◽  
Debris Avalanche ◽  
The Other ◽  
Strength Model ◽  
Whole Process ◽  
Element Method

In the present paper, the aim is at studying the kinematic process and deposit geometry of a potential rock avalanche in Italy. The rock fragmentation and the effect of different bonding strengths are evaluated. To simulate the sliding and destruction of the potential rock avalanche, a 3D discrete element software EDEM is employed. The results suggest that a dam will be formed nearly 70 sec after the avalanche occurs, and the maximum average velocity of the avalanche reaches over 40 m/s. The whole process can be split into 4 stages (instability, acceleration, fast sliding and decelerate deposition). There are three possible paths for debris to slide. The major path located in the middle, and the other 2 only have few rock debris. Furthermore, small bonding strength model of the discrete element method (DEM) applies to the simulation of the potential rock avalanche disasters, allowing the sliding in a form of debris avalanche with good liquidity.

A numerical solution for conducting bodies of arbitrary shape

1990 ◽  
Vol 68 (6) ◽  
pp. 459-468 ◽  
Author(s):  
H. Moheb ◽  
L. Shafai
Keyword(s):  
Electromagnetic Scattering ◽  
Arbitrary Shape ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Surface Current ◽  
Basis Functions ◽  
The Other ◽  
Current Component ◽  
Discrete Surfaces ◽  
Conducting Bodies

An efficient numerical technique based on a Fourier expansion of the surface current is developed to study the electromagnetic scattering from three-dimensional geometries of arbitrary shape. In this method, the discrete domain representing the structure surface is geometrically represented by two orthogonal contours. One is selected along the intersection of the x–z plane with the object's surface, and the other along the corresponding one in the x–y plane. Entire domain basis functions are selected for the current component in the x–y plane, and subdomain linear basis functions are used to represent the other current component. The method of moments is used to solve the problem numerically. The technique is then applied to study the scattering from discrete surfaces such as squares and rectangles, to compare them with those of the coordinate-transformation technique developed earlier. The behavior of the solutions with the number of modes is investigated to determine their coupling.

scholarly journals Crack nucleation in solid materials under external load - simulations with the Discrete Element Method

2018 ◽  
Vol 165 ◽  
pp. 22019
Author(s):  
Piotr Klejment ◽  
Wojciech Dębski
Keyword(s):  
Boundary Conditions ◽  
Discrete Element Method ◽  
Crack Nucleation ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Solid Material ◽  
Discrete Element ◽  
Biological Tissues ◽  
External Forces ◽  
Element Method

Numerical analysis of cracking processes require an appropriate numerical technique. Classical engineering approach to the problem has its roots in the continuum mechanics and is based mainly on the Finite Element Method. This technique allows simulations of both elastic and large deformation processes, so it is very popular in the engineering applications. However, a final effect of cracking - fragmentation of an object at hand can hardly be described by this approach in a numerically efficient way since it requires a solution of a problem of nontrivial evolving in time boundary conditions. We focused our attention on the Discrete Element Method (DEM), which by definition implies “molecular” construction of the matter. The basic idea behind DEM is to represent an investigated body as an assemblage of discrete particles interacting with each other. Breaking interaction bonds between particles induced by external forces imeditelly implies creation/evolution of boundary conditions. In this study we used the DEM approach to simulate cracking process in the three dimensional solid material under external tension. The used numerical model, although higly simplified, can be used to describe behaviour of such materials like thin films, biological tissues, metal coatings, to name a few.

Unsteady Surface Element Method

1981 ◽  
Vol 103 (4) ◽  
pp. 759-764 ◽  
Author(s):  
N. R. Keltner ◽  
J. V. Beck
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Finite Difference ◽  
Transient Heat Conduction ◽  
The Other ◽  
Surface Element ◽  
Contact Conductance ◽  
The Given ◽  
Duhamel’S Integral ◽  
Element Method

A method for the solution of transient heat conduction problems, called the unsteady surface element (USE) method, is developed and applied to several problems. The method is intended for thermally contacting bodies of similar or dissimilar geometries such as occur in contact conductance and intrinsic thermocouple problems. The method utilizes Duhamel’s integral in several ways. Two different procedures are presented, one utilizing temperature-based kernels and the other uses heat flux-based kernels. One of the given applications is to the intrinsic thermocouple problem. Several solutions are given and the results agree very well with two finite difference solutions.

A Conservative Iterative-Based Zonal Decomposition Scheme for Conduction Heat Transfer Problems

1999 ◽  
Vol 121 (1) ◽  
pp. 169-173 ◽  
Author(s):  
O. E. Ruiz ◽  
W. Z. Black
Keyword(s):  
Finite Difference ◽  
Numerical Technique ◽  
Accurate Solution ◽  
Relaxation Parameter ◽  
Decomposition Technique ◽  
Rapid Convergence ◽  
Conduction Heat Transfer ◽  
Decomposition Scheme ◽  
Transient Problems ◽  
Transfer Problems

A new conservative iterative-based zonal decomposition technique for the solution of complex heat conduction problems is proposed. This numerical technique is based on dividing the domain into subdomains and ensuring that the heat flux and temperature are continuous at the boundary between subdomains. An example problem is used to illustrate the zonal decomposition technique for both steady and transient problems. This numerical technique results in accuracy which equals or exceeds traditional finite difference solutions and solution times which are significantly less than traditional finite difference solutions. A numerical relaxation parameter is introduced and its value is optimized to provide the most rapid convergence to an accurate solution.

scholarly journals Stress Analysis of Three-Dimensional Media Containing Localized Zone by FEM-SGBEM Coupling

2011 ◽  
Vol 2011 ◽  
pp. 1-27
Author(s):  
Jaroon Rungamornrat ◽  
Sakravee Sripirom
Keyword(s):  
Stress Analysis ◽  
Boundary Element ◽  
Integral Equations ◽  
Boundary Integral Equations ◽  
Numerical Technique ◽  
Computational Cost ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Boundary Element Methods ◽  
Element Method

This paper presents an efficient numerical technique for stress analysis of three-dimensional infinite media containing cracks and localized complex regions. To enhance the computational efficiency of the boundary element methods generally found inefficient to treat nonlinearities and non-homogeneous data present within a domain and the finite element method (FEM) potentially demanding substantial computational cost in the modeling of an unbounded medium containing cracks, a coupling procedure exploiting positive features of both the FEM and a symmetric Galerkin boundary element method (SGBEM) is proposed. The former is utilized to model a finite, small part of the domain containing a complex region whereas the latter is employed to treat the remaining unbounded part possibly containing cracks. Use of boundary integral equations to form the key governing equation for the unbounded region offers essential benefits including the reduction of the spatial dimension and the corresponding discretization effort without the domain truncation. In addition, all involved boundary integral equations contain only weakly singular kernels thus allowing continuous interpolation functions to be utilized in the approximation and also easing the numerical integration. Nonlinearities and other complex behaviors within the localized regions are efficiently modeled by utilizing vast features of the FEM. A selected set of results is then reported to demonstrate the accuracy and capability of the technique.

Three-Dimensional Reconstruction of Two Forms of the Chaperonin GRO EL

1990 ◽  
Vol 48 (1) ◽  
pp. 258-259
Author(s):  
J.L. Carrascosa ◽  
G. Abella ◽  
S. Marco ◽  
M. Muyal ◽  
J.M. Carazo
Keyword(s):  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Series Method ◽  
Three Dimensional Reconstruction ◽  
Structural Components ◽  
E Coli ◽  
Dimensional Reconstruction ◽  
Morphogenetic Factors ◽  
Tilt Series

Chaperonins are a class of proteins characterized by their role as morphogenetic factors. They trantsiently interact with the structural components of certain biological aggregates (viruses, enzymes etc), promoting their correct folding, assembly and, eventually transport. The groEL factor from E. coli is a conspicuous member of the chaperonins, as it promotes the assembly and morphogenesis of bacterial oligomers and/viral structures.We have studied groEL-like factors from two different bacteria:E. coli and B.subtilis. These factors share common morphological features , showing two different views: one is 6-fold, while the other shows 7 morphological units. There is also a correlation between the presence of a dominant 6-fold view and the fact of both bacteria been grown at low temperature (32°C), while the 7-fold is the main view at higher temperatures (42°C). As the two-dimensional projections of groEL were difficult to interprete, we studied their three-dimensional reconstruction by the random conical tilt series method from negatively stained particles.

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