scholarly journals Thermally Induced Deformations in Nuclear Fuel Elements

2021 ◽  
Author(s):  
Haihui (Stella) Yang
Keyword(s):  
Fuel Element ◽  
Transfer Factor ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Beam Theory ◽  
Operating Conditions ◽  
Operational Parameters ◽  
Thermally Induced ◽  
Sensitivity Studies ◽  
Fuel Elements

Nonlinear three-dimensional multibody surface-surface contacts, thermally induced deformations, and the curvature transfer factor in CANDU fuel elements are investigated using the finite element method in this thesis. ANSYS is selected to obtain numerical solutions for CANDU fuel elements under several operating conditions. In the ANSYS models, the 20-node structural elements (SOLID186) are employed to mesch individual solids; the surface-to surface contact pairs (TARGE170 and CONTA174) are used to handle contacts between solids. Sensitivity studies on the curvature transfer factor are conducted for several key operational parameters. If there is full radial contact between the pellets and the sheath, a CANDU fuel element may be considered as a composite beam because of the large length-to-diameter ratio. The Timoshenko beam theory is used in conjunction with a three-node mean element to explore the thermal deformation behaviours of a fuel element. A program written in MATLAB is much more efficient compared with the ANSYS solutions.

scholarly journals Thermally Induced Deformations in Nuclear Fuel Elements

2021 ◽  
Author(s):  
Haihui (Stella) Yang
Keyword(s):  
Fuel Element ◽  
Transfer Factor ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Beam Theory ◽  
Operating Conditions ◽  
Operational Parameters ◽  
Thermally Induced ◽  
Sensitivity Studies ◽  
Fuel Elements

Nonlinear three-dimensional multibody surface-surface contacts, thermally induced deformations, and the curvature transfer factor in CANDU fuel elements are investigated using the finite element method in this thesis. ANSYS is selected to obtain numerical solutions for CANDU fuel elements under several operating conditions. In the ANSYS models, the 20-node structural elements (SOLID186) are employed to mesch individual solids; the surface-to surface contact pairs (TARGE170 and CONTA174) are used to handle contacts between solids. Sensitivity studies on the curvature transfer factor are conducted for several key operational parameters. If there is full radial contact between the pellets and the sheath, a CANDU fuel element may be considered as a composite beam because of the large length-to-diameter ratio. The Timoshenko beam theory is used in conjunction with a three-node mean element to explore the thermal deformation behaviours of a fuel element. A program written in MATLAB is much more efficient compared with the ANSYS solutions.

scholarly journals Large deformations of planar extensible beams and pantographic lattices: heuristic homogenization, experimental and numerical examples of equilibrium

2016 ◽  
Vol 472 (2185) ◽  
pp. 20150790 ◽  
Author(s):  
F. dell’Isola ◽  
I. Giorgio ◽  
M. Pawlikowski ◽  
N. L. Rizzi
Keyword(s):  
Large Deformations ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Beam Theory ◽  
Beam Model ◽  
Computationally Efficient ◽  
Nonlinear Beam ◽  
Pantographic Structures ◽  
Diffusion Of Technology ◽  
Second Gradient

The aim of this paper is to find a computationally efficient and predictive model for the class of systems that we call ‘pantographic structures’. The interest in these materials was increased by the possibilities opened by the diffusion of technology of three-dimensional printing. They can be regarded, once choosing a suitable length scale, as families of beams (also called fibres) interconnected to each other by pivots and undergoing large displacements and large deformations. There are, however, relatively few ‘ready-to-use’ results in the literature of nonlinear beam theory. In this paper, we consider a discrete spring model for extensible beams and propose a heuristic homogenization technique of the kind first used by Piola to formulate a continuum fully nonlinear beam model. The homogenized energy which we obtain has some peculiar and interesting features which we start to describe by solving numerically some exemplary deformation problems. Furthermore, we consider pantographic structures, find the corresponding homogenized second gradient deformation energies and study some planar problems. Numerical solutions for these two-dimensional problems are obtained via minimization of energy and are compared with some experimental measurements, in which elongation phenomena cannot be neglected.

scholarly journals Construction project of a long reach compact excavator

2021 ◽  
Vol 4 (4) ◽  
pp. 341-356
Author(s):  
Grzegorz Chomka ◽  
Michał Kondaszewski
Keyword(s):  
Construction Project ◽  
Three Dimensional ◽  
Optimal Solution ◽  
Operating Conditions ◽  
Technical Documentation ◽  
The Finite Element Method ◽  
Dimensional Model ◽  
Operational Parameters ◽  
Three Dimensional Model ◽  
Standard Operating

The purpose of thesis was to comprehensively develop the construction project of a long reach compact excavator. Optimal solution was selected and its frames were determined by carrying out classic structural calculations. Then, based on them, a preliminary three-dimensional model was designed in the CAD environment. The prototype was subjected to a series of verification calculations and simulation tests using the finite element method under typical, but also non-standard operating conditions. Then, the structure was optimized and then tested again. Next, technical documentation of the final version was created. In the final part of work, technical and operational parameters of designed compact excavator were summarized and the direction of further actions was determined. The thesis ended with a summary of the observations arose during its implementation.

Neutronic Analysis for Tehran Research Reactor Upgrading

2002 ◽  
Author(s):  
Ebrahim Afshar ◽  
Alireza Shahidi
Keyword(s):  
Research Reactor ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Monte Carlo Code ◽  
Radioisotope Production ◽  
The Core ◽  
Transport Code ◽  
Tehran Research Reactor ◽  
Fuel Elements ◽  
Good Agreement

This paper presents preliminary results of a study undertaken to investigate the possibility of raising the power of Tehran Research Reactor (TRR) from 5 to 10 MW (th), keeping the same core configuration and with minimum changes in the primary cooling circuit. The main aim of TRR upgrade is to increase the volume of radioisotope production. The neutronic analysis was carried out for a fresh core with 22 Standard Fuel Elements (SFE) under normal operating conditions. Two different calculational lines were used to simulate the neutronic behavior in the core and perform the necessary neutronic calculations. First, combination of cell calculation transport code WIMS-D/4 [1] and three dimensional core calculation diffusion code CITATION [2] were used to and next a Monte Carlo code MCNP-4B [3] together with point depletion code ORIGEN-2 [4] were used. The results obtained show good agreement between these two different schemes.

Dynamics and Control of the Bucket-Wheel Excavator: Part I — Dynamic Modeling of Bucket-Wheel Boom

2014 ◽  
Author(s):  
Quang Khanh Luu ◽  
Dirk Söffker
Keyword(s):  
Working Conditions ◽  
Nonlinear Modeling ◽  
Dynamical Behavior ◽  
Three Dimensional ◽  
Beam Theory ◽  
Higher Order ◽  
Operating Conditions ◽  
Flexible Beam ◽  
Dynamics And Control ◽  
External Forces

Bucket-Wheel excavators (BWE) represent a specific type of complex machine system used in mining technology. During operation, the system is exposed to a number of external forces and disturbances like digging resistances on the Bucket-Wheel that cause transverse, longitudinal, and torsional vibrations. All vibrations will affect to normal working conditions, operational effectiveness, and may under specific conditions also effect the stability of the BWE. To increase working conditions advanced control systems can be applied controlling the dynamics, especially induced structural vibrations. In order to analyze and synthesize a controller for the above mentioned system, adequate modeling to describe the dynamical behavior of the system under real operating conditions is necessary. In a previous investigation, it was assumed that the Bucket-Wheel boom can be modeled as a flexible beam using the Euler-Bernoulli beam theory. Additionally it is assumed that the boom is attached to the excavator turning platform. The nonlinear modeling of the three-dimensional elastic boom considering the elasticity of suspending cables and also couplings resulting from geometrical nonlinear deformations is presented. Here the known modeling approach of higher order is used and extended to model the Bucket-Wheel boom of a Bucket-Wheel-Excavator including guided rotating motion in combination with digging resistance forces. The dynamic phenomena resulting from the higher-order modeling including higher-order geometrical couplings as well as the external excitations on the dynamic behavior of the Bucket-Wheel boom are analyzed in detail. Intensive simulation studies are realized demonstrating the effect of higher-order couplings as well as resulting destabilizing effects from the modeling.

CFD Analysis of Flow in High-Radius Pre-Swirl Systems

2007 ◽  
Author(s):  
K. Jarzombek ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
O. Schneider
Keyword(s):  
Gas Turbines ◽  
Design Method ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Dimensional Structure ◽  
Operational Parameters ◽  
Flow Effects ◽  
Dynamics Simulations ◽  
Cooling Air

Pre-swirl systems of gas turbines are utilized to reduce the temperature of the cooling air during the transfer from the stationary into the rotating system of the turbine. The amount of temperature decrease between the pre-swirl nozzle and the receiver holes depends on many geometrical and operational parameters. For the design process of a cooling air system, simple but general 1D (one-dimensional) calculation methods are required. These models must comprise correlations describing all dominant flow effects in order to provide the most accurate results. For the development of such models, a good understanding of the flow behavior in the system is indispensable. In this contribution, a pre-swirl scheme consisting of the three main components: pre-swirl nozzle, pre-swirl cavity and receiver hole is investigated numerically for different configurations. The cavity of the system is described as a rotorstator system and as a rotor-rotor system. With both configurations, CFD (Computational Fluid Dynamics) simulations with the same set of boundary conditions are performed. The evaluation of the results shows the influence of each component on the three-dimensional structure of the flow. For different operating conditions, the flow inside the cavity is represented by streamlines and discussed in detail. In the cavity, the swirl distribution is shown for all configurations and compared to free vortex behavior. For some regions, where a strong decrease of total pressure is present, the flow pattern is described in detail. In view of the development of a 1D design method for a pre-swirl system, the described flow effects give some important hints.

A comparative study and combined application of RSM and ANN in adsorptive removal of diuron using biomass ashes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sunil K. Deokar ◽  
Nachiket A. Gokhale ◽  
Sachin A. Mandavgane
Keyword(s):  
Three Dimensional ◽  
Current Approach ◽  
Coefficient Of Determination ◽  
Ann Model ◽  
Operational Parameters ◽  
Initial Concentration ◽  
Combined Application ◽  
Artificial Neural Network Ann ◽  
Relationship Of ◽  
Biomass Ashes

Abstract Biomass ashes like rice husk ash (RHA), bagasse fly ash (BFA), were used for aqueous phase removal of a pesticide, diuron. Response surface methodology (RSM) and artificial neural network (ANN) were successfully applied to estimate and optimize the conditions for the maximum diuron adsorption using biomass ashes. The effect of operational parameters such as initial concentration (10–30 mg/L); contact time (0.93–16.07 h) and adsorbent dosage (20–308 mg) on adsorption were studied using central composite design (CCD) matrix. Same design was also employed to gain a training set for ANN. The maximum diuron removal of 88.95 and 99.78% was obtained at initial concentration of 15 mg/L, time of 12 h, RHA dosage of 250 mg and at initial concentration of 14 mg/L, time of 13 h, BFA dosage of 60 mg respectively. Estimation of coefficient of determination (R 2) and mean errors obtained for ANN and RSM (R 2 RHA = 0.976, R 2 BFA = 0.943) proved ANN (R 2 RHA = 0.997, R 2 BFA = 0.982) fits better. By employing RSM coupled with ANN model, the qualitative and quantitative activity relationship of experimental data was visualized in three dimensional spaces. The current approach will be instrumental in providing quick preliminary estimations in process and product development.

Numerical solutions for strain-softening surrounding rock under three-dimensional principal stress condition

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sheng Yu-ming ◽  
Li Chao ◽  
Xia Ming-yao ◽  
Zou Jin-feng
Keyword(s):  
Finite Element ◽  
Principal Stress ◽  
Stress Condition ◽  
Strain Softening ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Flow Rule ◽  
Finite Element Software

Abstract In this study, elastoplastic model for the surrounding rock of axisymmetric circular tunnel is investigated under three-dimensional (3D) principal stress states. Novel numerical solutions for strain-softening surrounding rock were first proposed based on the modified 3D Hoek–Brown criterion and the associated flow rule. Under a 3D axisymmetric coordinate system, the distributions for stresses and displacement can be effectively determined on the basis of the redeveloped stress increment approach. The modified 3D Hoek–Brown strength criterion is also embedded into finite element software to characterize the yielding state of surrounding rock based on the modified yield surface and stress renewal algorithm. The Euler implicit constitutive integral algorithm and the consistent tangent stiffness matrix are reconstructed in terms of the 3D Hoek–Brown strength criterion. Therefore, the numerical solutions and finite element method (FEM) models for the deep buried tunnel under 3D principal stress condition are presented, so that the stability analysis of surrounding rock can be conducted in a direct and convenient way. The reliability of the proposed solutions was verified by comparison of the principal stresses obtained by the developed numerical approach and FEM model. From a practical point of view, the proposed approach can also be applied for the determination of ground response curve of the tunnel, which shows a satisfying accuracy compared with the measuring data.

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