Search results for: finite elements method
22607 Optimization of Three-Layer Corrugated Metal Gasket by Using Finite Element Method
Authors: I Made Gatot Karohika, Shigeyuki Haruyama, Ken Kaminishi
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In this study, we proposed a three-layer metal gasket with Al, Cu, and SUS304 as the material, respectively. A finite element method was employed to develop simulation solution and design of experiment (DOE). Taguchi method was used to analysis the effect of each parameter design and predicts optimal design of new 25A-size three layer corrugated metal gasket. The L18 orthogonal array of Taguchi method was applied to design experiment matrix for eight factors with three levels. Based on elastic mode and plastic mode, optimum design gasket is gasket with core metal SUS304, surface layer aluminum, p1 = 4.5 mm, p2 = 4.5 mm, p3 = 4 mm, Tg = 1.2 mm, R = 3.5 mm, h = 0.4 mm and Ts = 0.3 mm.Keywords: contact width, contact stress, layer, metal gasket, corrugated, simulation
Procedia PDF Downloads 31722606 Strength Investigation of Liquefied Petroleum Gas Cylinders: Dynamic Loads
Authors: Moudar Zgoul, Hashem Alkhaldi
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A large number of transportable LPG cylinders are manufactured annually for domestic use. These LPG cylinders are manufactured from mild steel and filled maximally with 12.5 kg liquefied gas under internal pressure of 0.6 N/mm² at a temperature of 50°C. Many millions of such LPG cylinders are in daily use mainly, for purposes of space heating, water heating, and cooking. Thereby, they are imposed to severe conditions leading to their failure. Each year not less than 5000 of these LPG cylinders fail, some of those failures cause damage and loss in lives and properties. In this work, LPG cylinders were investigated; Stress calculations and deformations under dynamic (impact) loadings were carried out to simulate the effects of such loads on the cylinders while in service. Analysis of the LPG cylinders was carried out using the finite element method; shell and cylindrical elements were used at the top, bottom, and in middle (weld region), permitting elastic-plastic analysis for a thin-walled LPG cylinder. Variables such as maximum stresses and maximum deflections under the effect of impact loading were investigated in this work. Results showed that the maximum stresses reach 680 MPa when dropped from 3m-height. The maximum radial deformation occurs at the cylinder’s top in case of the top-position impact. This information should be useful for enhancing the strength of such cylinders and to for prolonging their service life.Keywords: dynamic analysis, finite element method, impact load, LPG cylinders
Procedia PDF Downloads 32522605 Application of the Finite Window Method to a Time-Dependent Convection-Diffusion Equation
Authors: Raoul Ouambo Tobou, Alexis Kuitche, Marcel Edoun
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The FWM (Finite Window Method) is a new numerical meshfree technique for solving problems defined either in terms of PDEs (Partial Differential Equation) or by a set of conservation/equilibrium laws. The principle behind the FWM is that in such problem each element of the concerned domain is interacting with its neighbors and will always try to adapt to keep in equilibrium with respect to those neighbors. This leads to a very simple and robust problem solving scheme, well suited for transfer problems. In this work, we have applied the FWM to an unsteady scalar convection-diffusion equation. Despite its simplicity, it is well known that convection-diffusion problems can be challenging to be solved numerically, especially when convection is highly dominant. This has led researchers to set the scalar convection-diffusion equation as a benchmark one used to analyze and derive the required conditions or artifacts needed to numerically solve problems where convection and diffusion occur simultaneously. We have shown here that the standard FWM can be used to solve convection-diffusion equations in a robust manner as no adjustments (Upwinding or Artificial Diffusion addition) were required to obtain good results even for high Peclet numbers and coarse space and time steps. A comparison was performed between the FWM scheme and both a first order implicit Finite Volume Scheme (Upwind scheme) and a third order implicit Finite Volume Scheme (QUICK Scheme). The results of the comparison was that for equal space and time grid spacing, the FWM yields a much better precision than the used Finite Volume schemes, all having similar computational cost and conditioning number.Keywords: Finite Window Method, Convection-Diffusion, Numerical Technique, Convergence
Procedia PDF Downloads 33322604 A Simple Finite Element Method for Glioma Tumor Growth Model with Density Dependent Diffusion
Authors: Shangerganesh Lingeshwaran
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In this presentation, we have performed numerical simulations for a reaction-diffusion equation with various nonlinear density-dependent diffusion operators and proliferation functions. The mathematical model represented by parabolic partial differential equation is considered to study the invasion of gliomas (the most common type of brain tumors) and to describe the growth of cancer cells and response to their treatment. The unknown quantity of the given reaction-diffusion equation is the density of cancer cells and the mathematical model based on the proliferation and migration of glioma cells. A standard Galerkin finite element method is used to perform the numerical simulations of the given model. Finally, important observations on the each of nonlinear diffusion functions and proliferation functions are presented with the help of computational results.Keywords: glioma invasion, nonlinear diffusion, reaction-diffusion, finite eleament method
Procedia PDF Downloads 23322603 Determination of Mercury in Gold Ores by CVAAS Method
Authors: Ratna Siti Khodijah, Mirzam Abdurrachman
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Gold is recovered from gold ores. Within the ores, there are not only gold but also several types of precious metals. Copper, silver, and platinum group elements (ruthenium, rhodium, palladium, rhenium, osmium, and iridium) are metals commonly found in the ores. These metals combine to form an ore because they have the same properties. It is due to their position in periodic-system-of-elements are near to gold. However, the presence of mercury in every gold ore has not been mentioned, even though it is located right next to gold in the periodic-system-of-elements and they are located in the same block, d-block. Thus, it is possible that mercury is contained in the ores. Moreover, the elements of the same group with mercury—zinc and cadmium—sometimes can be found in the ores. It is suspected that mercury can not be detected because the processing of gold ores usually using fire assay method. Before the ores melting, mercury would evaporate because it has the lowest boiling point of all precious metal in the ores. Therefore, it suggested doing research on the presence of mercury in gold ores by CVAAS method. The results of this study would obtain the amount of mercury in gold ores that should be purified. So it can be produced economically if possible.Keywords: boiling point, d-block, fire assay, precious metal
Procedia PDF Downloads 34122602 A Guide for Using Viscoelasticity in ANSYS
Authors: A. Fettahoglu
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Theory of viscoelasticity is used by many researchers to represent the behavior of many materials such as pavements on roads or bridges. Several researches used analytical methods and rheology to predict the material behaviors of simple models. Today, more complex engineering structures are analyzed using Finite Element Method, in which material behavior is embedded by means of three dimensional viscoelastic material laws. As a result, structures of unordinary geometry and domain can be analyzed by means of Finite Element Method and three dimensional viscoelastic equations. In the scope of this study, rheological models embedded in ANSYS, namely, generalized Maxwell model and Prony series, which are two methods used by ANSYS to represent viscoelastic material behavior, are presented explicitly. Afterwards, a guide is illustrated to ease using of viscoelasticity tool in ANSYS.Keywords: ANSYS, generalized Maxwell model, finite element method, Prony series, viscoelasticity, viscoelastic material curve fitting
Procedia PDF Downloads 61122601 An Implicit Methodology for the Numerical Modeling of Locally Inextensible Membranes
Authors: Aymen Laadhari
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We present in this paper a fully implicit finite element method tailored for the numerical modeling of inextensible fluidic membranes in a surrounding Newtonian fluid. We consider a highly simplified version of the Canham-Helfrich model for phospholipid membranes, in which the bending force and spontaneous curvature are disregarded. The coupled problem is formulated in a fully Eulerian framework and the membrane motion is tracked using the level set method. The resulting nonlinear problem is solved by a Newton-Raphson strategy, featuring a quadratic convergence behavior. A monolithic solver is implemented, and we report several numerical experiments aimed at model validation and illustrating the accuracy of the proposed method. We show that stability is maintained for significantly larger time steps with respect to an explicit decoupling method.Keywords: finite element method, level set, Newton, membrane
Procedia PDF Downloads 33022600 Thermo-Mechanical Behavior of Steel-Wood Connections of Wooden Structures Under the Effect of a Fire
Authors: Ahmed Alagha, Belkacem Lamri, Abdelhak Kada.
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Steel-wood assemblies often have complex geometric configurations whose overall behavior under the effect of a fire is conditioned by the thermal response, by combining the two materials steel and wood, whose thermal characteristics are greatly influenced by high temperatures. The objective of this work is to study the thermal behavior of a steel-wood connection, with or without insulating material, subjected to an ISO834 standard fire model. The analysis is developed by the analytical approach using the Eurocode, and numerically, by the finite element method, through the ANSYS calculation code. The design of the connections is evaluated at room temperature taking the cases of single shear and double shear. The thermal behavior of the connections is simulated in transient state while taking into account the modes of heat transfer by convection and by radiation. The variation of temperature as a function of time is evaluated in different positions of the connections while talking about the heat produced and the formation of the carbon layer. The results relate to the temperature distributions in the connection elements as a function of the duration of the fire. The results of the thermal analysis show that the temperature increases rapidly and reaches more than 260 °C in the steel material for an hour of exposure to fire. The temperature development in wood material is different from that in steel because of its thermal properties. Wood heats up on the outside and burns, its surface can reach very high temperatures in points on the surface.Keywords: Eurocode 5, finite elements, ISO834, simple shear, thermal behaviour, wood-steel connection
Procedia PDF Downloads 8622599 The Simulation and Experimental Investigation to Study the Strain Distribution Pattern during the Closed Die Forging Process
Authors: D. B. Gohil
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Closed die forging is a very complex process, and measurement of actual forces for real material is difficult and time consuming. Hence, the modelling technique has taken the advantage of carrying out the experimentation with the proper model material which needs lesser forces and relatively low temperature. The results of experiments on the model material then may be correlated with the actual material by using the theory of similarity. There are several methods available to resolve the complexity involved in the closed die forging process. Finite Element Method (FEM) and Finite Difference Method (FDM) are relatively difficult as compared to the slab method. The slab method is very popular and very widely used by the people working on shop floor because it is relatively easy to apply and reasonably accurate for most of the common forging load requirement computations.Keywords: experimentation, forging, process modeling, strain distribution
Procedia PDF Downloads 20222598 Compressible Lattice Boltzmann Method for Turbulent Jet Flow Simulations
Authors: K. Noah, F.-S. Lien
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In Computational Fluid Dynamics (CFD), there are a variety of numerical methods, of which some depend on macroscopic model representatives. These models can be solved by finite-volume, finite-element or finite-difference methods on a microscopic description. However, the lattice Boltzmann method (LBM) is considered to be a mesoscopic particle method, with its scale lying between the macroscopic and microscopic scales. The LBM works well for solving incompressible flow problems, but certain limitations arise from solving compressible flows, particularly at high Mach numbers. An improved lattice Boltzmann model for compressible flow problems is presented in this research study. A higher-order Taylor series expansion of the Maxwell equilibrium distribution function is used to overcome limitations in LBM when solving high-Mach-number flows. Large eddy simulation (LES) is implemented in LBM to simulate turbulent jet flows. The results have been validated with available experimental data for turbulent compressible free jet flow at subsonic speeds.Keywords: compressible lattice Boltzmann method, multiple relaxation times, large eddy simulation, turbulent jet flows
Procedia PDF Downloads 27522597 Mathematical Modeling of the AMCs Cross-Contamination Removal in the FOUPs: Finite Element Formulation and Application in FOUP’s Decontamination
Authors: N. Santatriniaina, J. Deseure, T. Q. Nguyen, H. Fontaine, C. Beitia, L. Rakotomanana
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Nowadays, with the increasing of the wafer's size and the decreasing of critical size of integrated circuit manufacturing in modern high-tech, microelectronics industry needs a maximum attention to challenge the contamination control. The move to 300 mm is accompanied by the use of Front Opening Unified Pods for wafer and his storage. In these pods an airborne cross contamination may occur between wafers and the pods. A predictive approach using modeling and computational methods is very powerful method to understand and qualify the AMCs cross contamination processes. This work investigates the required numerical tools which are employed in order to study the AMCs cross-contamination transfer phenomena between wafers and FOUPs. Numerical optimization and finite element formulation in transient analysis were established. Analytical solution of one dimensional problem was developed and the calibration process of physical constants was performed. The least square distance between the model (analytical 1D solution) and the experimental data are minimized. The behavior of the AMCs intransient analysis was determined. The model framework preserves the classical forms of the diffusion and convection-diffusion equations and yields to consistent form of the Fick's law. The adsorption process and the surface roughness effect were also traduced as a boundary condition using the switch condition Dirichlet to Neumann and the interface condition. The methodology is applied, first using the optimization methods with analytical solution to define physical constants, and second using finite element method including adsorption kinetic and the switch of Dirichlet to Neumann condition.Keywords: AMCs, FOUP, cross-contamination, adsorption, diffusion, numerical analysis, wafers, Dirichlet to Neumann, finite elements methods, Fick’s law, optimization
Procedia PDF Downloads 50922596 An Implementation of Meshless Method for Modeling an Elastoplasticity Coupled to Damage
Authors: Sendi Zohra, Belhadjsalah Hedi, Labergere Carl, Saanouni Khemais
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The modeling of mechanical problems including both material and geometric nonlinearities with Finite Element Method (FEM) remains challenging. Meshless methods offer special properties to get rid of well-known drawbacks of the FEM. The main objective of Meshless Methods is to eliminate the difficulty of meshing and remeshing the entire structure by simply insertion or deletion of nodes, and alleviate other problems associated with the FEM, such as element distortion, locking and others. In this study, a robust numerical implementation of an Element Free Galerkin Method for an elastoplastic coupled to damage problem is presented. Several results issued from the numerical simulations by a DynamicExplicit resolution scheme are analyzed and critically compared with Element Finite Method results. Finally, different numerical examples are carried out to demonstrate the efficiency of this method.Keywords: damage, dynamic explicit, elastoplasticity, isotropic hardening, meshless
Procedia PDF Downloads 29522595 Coupling of Two Discretization Schemes for the Lattice Boltzmann Equation
Authors: Tobias Horstmann, Thomas Le Garrec, Daniel-Ciprian Mincu, Emmanuel Lévêque
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Despite the efficiency and low dissipation of the stream-collide formulation of the Lattice Boltzmann (LB) algorithm, which is nowadays implemented in many commercial LBM solvers, there are certain situations, e.g. mesh transition, in which a classical finite-volume or finite-difference formulation of the LB algorithm still bear advantages. In this paper, we present an algorithm that combines the node-based streaming of the distribution functions with a second-order finite volume discretization of the advection term of the BGK-LB equation on a uniform D2Q9 lattice. It is shown that such a coupling is possible for a multi-domain approach as long as the overlap, or buffer zone, between two domains, is achieved on at least 2Δx. This also implies that a direct coupling (without buffer zone) of a stream-collide and finite-volume LB algorithm on a single grid is not stable. The critical parameter in the coupling is the CFL number equal to 1 that is imposed by the stream-collide algorithm. Nevertheless, an explicit filtering step on the finite-volume domain can stabilize the solution. In a further investigation, we demonstrate how such a coupling can be used for mesh transition, resulting in an intrinsic conservation of mass over the interface.Keywords: algorithm coupling, finite volume formulation, grid refinement, Lattice Boltzmann method
Procedia PDF Downloads 38022594 A Comparative Study of the Athlete Health Records' Minimum Data Set in Selected Countries and Presenting a Model for Iran
Authors: Robab Abdolkhani, Farzin Halabchi, Reza Safdari, Goli Arji
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Background and purpose: The quality of health record depends on the quality of its content and proper documentation. Minimum data set makes a standard method for collecting key data elements that make them easy to understand and enable comparison. The aim of this study was to determine the minimum data set for Iranian athletes’ health records. Methods: This study is an applied research of a descriptive comparative type which was carried out in 2013. By using internal and external forms of documentation, a checklist was created that included data elements of athletes health record and was subjected to debate in Delphi method by experts in the field of sports medicine and health information management. Results: From 97 elements which were subjected to discussion, 85 elements by more than 75 percent of the participants (as the main elements) and 12 elements by 50 to 75 percent of the participants (as the proposed elements) were agreed upon. In about 97 elements of the case, there was no significant difference between responses of alumni groups of sport pathology and sports medicine specialists with medical record, medical informatics and information management professionals. Conclusion: Minimum data set of Iranian athletes’ health record with four information categories including demographic information, health history, assessment and treatment plan was presented. The proposed model is available for manual and electronic medical records.Keywords: Documentation, Health record, Minimum data set, Sports medicine
Procedia PDF Downloads 48322593 Finite Element and Split Bregman Methods for Solving a Family of Optimal Control Problem with Partial Differential Equation Constraint
Authors: Mahmoud Lot
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In this article, we will discuss the solution of elliptic optimal control problem. First, by using the nite element method, we obtain the discrete form of the problem. The obtained discrete problem is actually a large scale constrained optimization problem. Solving this optimization problem with traditional methods is difficult and requires a lot of CPU time and memory. But split Bergman method converts the constrained problem to an unconstrained, and hence it saves time and memory requirement. Then we use the split Bregman method for solving this problem, and examples show the speed and accuracy of split Bregman methods for solving these types of problems. We also use the SQP method for solving the examples and compare with the split Bregman method.Keywords: Split Bregman Method, optimal control with elliptic partial differential equation constraint, finite element method
Procedia PDF Downloads 15222592 Analysis of Cyclic Elastic-Plastic Loading of Shaft Based on Kinematic Hardening Model
Authors: Isa Ahmadi, Ramin Khamedi
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In this paper, the elasto-plastic and cyclic torsion of a shaft is studied using a finite element method. The Prager kinematic hardening theory of plasticity with the Ramberg and Osgood stress-strain equation is used to evaluate the cyclic loading behavior of the shaft under the torsional loading. The material of shaft is assumed to follow the non-linear strain hardening property based on the Prager model. The finite element method with C1 continuity is developed and used for solution of the governing equations of the problem. The successive substitution iterative method is used to calculate the distribution of stresses and plastic strains in the shaft due to cyclic loads. The shear stress, effective stress, residual stress and elastic and plastic shear strain distribution are presented in the numerical results.Keywords: cyclic loading, finite element analysis, Prager kinematic hardening model, torsion of shaft
Procedia PDF Downloads 41022591 A Comparative Study of High Order Rotated Group Iterative Schemes on Helmholtz Equation
Authors: Norhashidah Hj. Mohd Ali, Teng Wai Ping
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In this paper, we present a high order group explicit method in solving the two dimensional Helmholtz equation. The presented method is derived from a nine-point fourth order finite difference approximation formula obtained from a 45-degree rotation of the standard grid which makes it possible for the construction of iterative procedure with reduced complexity. The developed method will be compared with the existing group iterative schemes available in literature in terms of computational time, iteration counts, and computational complexity. The comparative performances of the methods will be discussed and reported.Keywords: explicit group method, finite difference, helmholtz equation, rotated grid, standard grid
Procedia PDF Downloads 45722590 Modeling of Large Elasto-Plastic Deformations by the Coupled FE-EFGM
Authors: Azher Jameel, Ghulam Ashraf Harmain
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In the recent years, the enriched techniques like the extended finite element method, the element free Galerkin method, and the Coupled finite element-element free Galerkin method have found wide application in modeling different types of discontinuities produced by cracks, contact surfaces, and bi-material interfaces. The extended finite element method faces severe mesh distortion issues while modeling large deformation problems. The element free Galerkin method does not have mesh distortion issues, but it is computationally more demanding than the finite element method. The coupled FE-EFGM proves to be an efficient numerical tool for modeling large deformation problems as it exploits the advantages of both FEM and EFGM. The present paper employs the coupled FE-EFGM to model large elastoplastic deformations in bi-material engineering components. The large deformation occurring in the domain has been modeled by using the total Lagrangian approach. The non-linear elastoplastic behavior of the material has been represented by the Ramberg-Osgood model. The elastic predictor-plastic corrector algorithms are used for the evaluation stresses during large deformation. Finally, several numerical problems are solved by the coupled FE-EFGM to illustrate its applicability, efficiency and accuracy in modeling large elastoplastic deformations in bi-material samples. The results obtained by the proposed technique are compared with the results obtained by XFEM and EFGM. A remarkable agreement was observed between the results obtained by the three techniques.Keywords: XFEM, EFGM, coupled FE-EFGM, level sets, large deformation
Procedia PDF Downloads 44822589 Simulation of Non-Crimp 3D Orthogonal Carbon Fabric Composite for Aerospace Applications Using Finite Element Method
Authors: Sh. Minapoor, S. Ajeli, M. Javadi Toghchi
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Non-crimp 3D orthogonal fabric composite is one of the textile-based composite materials that are rapidly developing light-weight engineering materials. The present paper focuses on geometric and micro mechanical modeling of non-crimp 3D orthogonal carbon fabric and composites reinforced with it for aerospace applications. In this research meso-finite element (FE) modeling employs for stress analysis in different load conditions. Since mechanical testing of expensive textile carbon composites with specific application isn't affordable, simulation composite in a virtual environment is a helpful way to investigate its mechanical properties in different conditions.Keywords: woven composite, aerospace applications, finite element method, mechanical properties
Procedia PDF Downloads 46522588 Numerical Investigation of Poling Vector Angle on Adaptive Sandwich Plate Deflection
Authors: Alireza Pouladkhan, Mohammad Yavari Foroushani, Ali Mortazavi
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This paper presents a finite element model for a sandwich plate containing a piezoelectric core. A sandwich plate with a piezoelectric core is constructed using the shear mode of piezoelectric materials. The orientation of poling vector has a significant effect on deflection and stress induced in the piezo-actuated adaptive sandwich plate. In the present study, the influence of this factor for a clamped-clamped-free-free and simple-simple-free-free square sandwich plate is investigated using Finite Element Method. The study uses ABAQUS (v.6.7) software to derive the finite element model of the sandwich plate. By using this model, the study gives the influences of the poling vector angle on the response of the smart structure and determines the maximum transverse displacement and maximum stress induced.Keywords: finite element method, sandwich plate, poling vector, piezoelectric materials, smart structure, electric enthalpy
Procedia PDF Downloads 23322587 Comparison of ANN and Finite Element Model for the Prediction of Ultimate Load of Thin-Walled Steel Perforated Sections in Compression
Authors: Zhi-Jun Lu, Qi Lu, Meng Wu, Qian Xiang, Jun Gu
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The analysis of perforated steel members is a 3D problem in nature, therefore the traditional analytical expressions for the ultimate load of thin-walled steel sections cannot be used for the perforated steel member design. In this study, finite element method (FEM) and artificial neural network (ANN) were used to simulate the process of stub column tests based on specific codes. Results show that compared with those of the FEM model, the ultimate load predictions obtained from ANN technique were much closer to those obtained from the physical experiments. The ANN model for the solving the hard problem of complex steel perforated sections is very promising.Keywords: artificial neural network (ANN), finite element method (FEM), perforated sections, thin-walled Steel, ultimate load
Procedia PDF Downloads 35222586 Structural Evaluation of Airfield Pavement Using Finite Element Analysis Based Methodology
Authors: Richard Ji
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Nondestructive deflection testing has been accepted widely as a cost-effective tool for evaluating the structural condition of airfield pavements. Backcalculation of pavement layer moduli can be used to characterize the pavement existing condition in order to compute the load bearing capacity of pavement. This paper presents an improved best-fit backcalculation methodology based on deflection predictions obtained using finite element method (FEM). The best-fit approach is based on minimizing the squared error between falling weight deflectometer (FWD) measured deflections and FEM predicted deflections. Then, concrete elastic modulus and modulus of subgrade reaction were back-calculated using Heavy Weight Deflectometer (HWD) deflections collected at the National Airport Pavement Testing Facility (NAPTF) test site. It is an alternative and more versatile method in considering concrete slab geometry and HWD testing locations compared to methods currently available.Keywords: nondestructive testing, pavement moduli backcalculation, finite element method, concrete pavements
Procedia PDF Downloads 16722585 Modal FDTD Method for Wave Propagation Modeling Customized for Parallel Computing
Authors: H. Samadiyeh, R. Khajavi
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A new FD-based procedure, modal finite difference method (MFDM), is proposed for seismic wave propagation modeling, in which simulation is dealt with in the modal space. The method employs eigenvalues of a characteristic matrix formed by appropriate time-space FD stencils. Since MFD runs for different modes are totally independent of each other, MFDM can easily be parallelized while considerable simplicity in parallel-algorithm is also achieved. There is no requirement to any domain-decomposition procedure and inter-core data exchange. More important is the possibility to skip processing of less-significant modes, which enables one to adjust the procedure up to the level of accuracy needed. Thus, in addition to considerable ease of parallel programming, computation and storage costs are significantly reduced. The method is qualified for its efficiency by some numerical examples.Keywords: Finite Difference Method, Graphics Processing Unit (GPU), Message Passing Interface (MPI), Modal, Wave propagation
Procedia PDF Downloads 29722584 The Influence of Size on Fused Silica Strength: A Multi-Method Study
Authors: Şeyma Saliha Fidan, Rahmi Ünal
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Ceramic materials exhibit inherently brittle behavior, primarily attributed to the presence of flaws that severely restrict their applicability as structural elements under tensile loading. This brittleness necessitates special attention in the design of ceramic components, with a particular focus on appropriately addressing stress distribution. Among the most commonly used uniaxial testing methods to evaluate the mechanical behavior of ceramics are three-point bending and four-point bending tests. Each of these methods induces a unique stress distribution within the specimen. Using Weibull theory and its fundamental assumptions, it is possible to account for the different stress fields produced by each testing method and compare the resulting strength data. This comparison is based on the concept of effective volume or area. In this study, slip-cast fused silica ceramics were selected as the material of interest. The study aims to apply Weibull statistical theory to various testing methods, integrating statistical tools and finite element method (FEM) simulations. A validated FEM-based approach was developed to determine the effective volumes of the specimens. The effective volume values obtained through analytical and numerical methods were compared, and the stress fields generated by different testing methods were evaluated based on Weibull theory. Moreover, the effective volume calculation procedure derived from numerical analysis methods has been adapted for use in complex test geometries and various loading conditions.Keywords: ceramic, fused silica, effective volume, Weibull analysis, finite element method
Procedia PDF Downloads 622583 Hybrid Finite Element Analysis of Expansion Joints for Piping Systems in Aircraft Engine External Configurations and Nuclear Power Plants
Authors: Dong Wook Lee
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This paper presents a method to analyze the stiffness of the expansion joint with structural support using a hybrid method combining computational and analytical methods. Many expansion joints found in tubes and ducts of mechanical structures are designed to absorb thermal expansion mismatch between their structural members and deal with misalignments introduced from the assembly/manufacturing processes. One of the important design perspectives is the system’s vibrational characteristics. We calculate the stiffness as a characterization parameter for structural joint systems using a combined Finite Element Analysis (FEA) and an analytical method. We apply the methods to two sample applications: external configurations of aircraft engines and nuclear power plant structures.Keywords: expansion joint, expansion joint stiffness, finite element analysis, nuclear power plants, aircraft engine external configurations
Procedia PDF Downloads 11122582 Viscoelastic Modeling of Hot Mix Asphalt (HMA) under Repeated Loading by Using Finite Element Method
Authors: S. A. Tabatabaei, S. Aarabi
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Predicting the hot mix asphalt (HMA) response and performance is a challenging task because of the subjectivity of HMA under the complex loading and environmental condition. The behavior of HMA is a function of temperature of loading and also shows the time and rate-dependent behavior directly affecting design criteria of mixture. Velocity of load passing make the time and rate. The viscoelasticity illustrates the reaction of HMA under loading and environmental conditions such as temperature and moisture effect. The behavior has direct effect on design criteria such as tensional strain and vertical deflection. In this paper, the computational framework for viscoelasticity and implementation in 3D dimensional HMA model is introduced to use in finite element method. The model was lied under various repeated loading conditions at constant temperature. The response of HMA viscoelastic behavior is investigated in loading condition under speed vehicle and sensitivity of behavior to the range of speed and compared to HMA which is supposed to have elastic behavior as in conventional design methods. The results show the importance of loading time pulse, unloading time and various speeds on design criteria. Also the importance of memory fading of material to storing the strain and stress due to repeated loading was shown. The model was simulated by ABAQUS finite element packageKeywords: viscoelasticity, finite element method, repeated loading, HMA
Procedia PDF Downloads 39822581 Effectiveness of Earthing System in Vertical Configurations
Authors: S. Yunus, A. Suratman, N. Mohamad Nor, M. Othman
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This paper presents the measurement and simulation results by Finite Element Method (FEM) for earth resistance (RDC) for interconnected vertical ground rod configurations. The soil resistivity was measured using the Wenner four-pin Method, and RDC was measured using the Fall of Potential (FOP) method, as outlined in the standard. Genetic Algorithm (GA) is employed to interpret the soil resistivity to that of a 2-layer soil model. The same soil resistivity data that were obtained by Wenner four-pin method were used in FEM for simulation. This paper compares the results of RDC obtained by FEM simulation with the real measurement at field site. A good agreement was seen for RDC obtained by measurements and FEM. This shows that FEM is a reliable software to be used for design of earthing systems. It is also found that the parallel rod system has a better performance compared to a similar setup using a grid layout.Keywords: earthing system, earth electrodes, finite element method, genetic algorithm, earth resistances
Procedia PDF Downloads 11022580 The Different Ways to Describe Regular Languages by Using Finite Automata and the Changing Algorithm Implementation
Authors: Abdulmajid Mukhtar Afat
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This paper aims at introducing finite automata theory, the different ways to describe regular languages and create a program to implement the subset construction algorithms to convert nondeterministic finite automata (NFA) to deterministic finite automata (DFA). This program is written in c++ programming language. The program reads FA 5tuples from text file and then classifies it into either DFA or NFA. For DFA, the program will read the string w and decide whether it is acceptable or not. If accepted, the program will save the tracking path and point it out. On the other hand, when the automation is NFA, the program will change the Automation to DFA so that it is easy to track and it can decide whether the w exists in the regular language or not.Keywords: finite automata, subset construction, DFA, NFA
Procedia PDF Downloads 42722579 Simultaneous Analysis of 25 Trace Elements in Micro Volume of Human Serum by Inductively Coupled Plasma–Mass Spectrometry
Authors: Azmawati Mohammed Nawi, Siok-Fong Chin, Shamsul Azhar Shah, Rahman Jamal
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In recent years, trace elements have gained importance as biomarkers in many chronic diseases. Unfortunately, the requirement for sample volume increases according to the extent of investigation for diagnosis or elucidating the mechanism of the disease. Here, we describe the method development and validation for simultaneous determination of 25 trace elements (lithium (Li), beryllium (Be), magnesium (Mg), aluminium (Al), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), arsenic (As), selenium (Se), rubidium (Rb), strontium (Sr), silver (Ag), cadmium (Cd), caesium (Cs), barium (Ba), mercury (Hg), thallium (Tl), lead (Pb), uranium (U)) using just 20 µL of human serum. Serum samples were digested with nitric acid and hydrochloric acid (ratio 1:1, v/v) and analysed using inductively coupled plasma–mass spectrometry (ICP-MS). Seronorm®, a human-derived serum control material was used as quality control samples. The intra-day and inter-day precisions were consistently < 15% for all elements. The validated method was later applied to 30 human serum samples to evaluate its suitability. In conclusion, we have successfully developed and validated a precise and accurate analytical method for determining 25 trace elements requiring very low volume of human serum.Keywords: acid digestion, ICP-MS, trace element, serum
Procedia PDF Downloads 18522578 Crack Width Analysis of Reinforced Concrete Members under Shrinkage Effect by Pseudo-Discrete Crack Model
Authors: F. J. Ma, A. K. H. Kwan
Abstract:
Crack caused by shrinkage movement of concrete is a serious problem especially when restraint is provided. It may cause severe serviceability and durability problems. The existing prediction methods for crack width of concrete due to shrinkage movement are mainly numerical methods under simplified circumstances, which do not agree with each other. To get a more unified prediction method applicable to more sophisticated circumstances, finite element crack width analysis for shrinkage effect should be developed. However, no existing finite element analysis can be carried out to predict the crack width of concrete due to shrinkage movement because of unsolved reasons of conventional finite element analysis. In this paper, crack width analysis implemented by finite element analysis is presented with pseudo-discrete crack model, which combines traditional smeared crack model and newly proposed crack queuing algorithm. The proposed pseudo-discrete crack model is capable of simulating separate and single crack without adopting discrete crack element. And the improved finite element analysis can successfully simulate the stress redistribution when concrete is cracked, which is crucial for predicting crack width, crack spacing and crack number.Keywords: crack queuing algorithm, crack width analysis, finite element analysis, shrinkage effect
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