Application Of Finite Element Technique Research Articles

Surrogate-assisted optimization for augmentation of finite element techniques

The application of finite element techniques for the analysis and optimization of complex thermo-mechanical structures typically involves highly nonlinear models for material characterization, tribological contact, large deformation, damage, etc. These nonlinearities usually call for a higher order spatio-temporal discretization, including a large number of elements and time-steps in order to provide good convergence and sufficiently accurate simulation results. Unfortunately, this inevitably leads to many expensive simulations in terms of cost and time if an optimization or adaption of design parameters has to be done. In this work, a surrogate-assisted optimization algorithm is utilized to find the setting of design parameters, which would lead to maximum damage in a simple tensile testing scenario involving a notched specimen with as few FEM simulations as possible.

Analysis of Composite Panels of Profiled Steel Sheet with Ferrocement by Using Finite Element Method

This paper concerns with the application of finite element technique to the nonlinear analysis of the behavior of profiled steel sheet ferrocement (PSSF) composite panels. The composite panels were analyzed using nonlinear three dimensional finite element models. The constitutive models of the nonlinear material behavior for ferrocement matrix, PSS, and steel wire mesh were used. ANSYS version 16.1 program code was used to analyze the three dimensional model. Ferrocement was modeled by using the 8-noded isoperimetric brick elements (SOLID65) with three degrees of freedom, while the profiled steel sheet was modeled as SHELL181 element with four-node element with six degrees of freedom at each node: translations in the x, y, and z directions, and rotations about the x, y, and z-axes. A nonlinear spring element, COMBIN14, was used to represent the mechanical connectors, while to simulate the adhesive epoxy layer solid element SOLID185 was used. It was defined by eight nodes having three degrees of freedom at each node: translations in the nodal x, y, and z directions. The wire mesh reinforcement was modeled as a volume ratio distributed within the ferrocement brick elements. The analytical results of load-deflection response have been compared with available experimental works.

Evaluation of Residual Stresses in Butt Welded Joint of Dissimilar Material by FEM

The study proposed within this paper deals with an application of finite element techniques to the thermo-structural analysis of a dissimilar butt-welded joint. Residual stresses induced by the fusion arc-welding of steel joints in power generation plants are a concern to the industry. Nowadays, the application of finite element method appears to be a very efficient method for the prediction and the investigation of the weld-induced residual stresses, nevertheless the detailed modelling of all phenomena involved in such process is still challenging. The structural integrity assessment of welded structures strongly requires a deep investigation of weld-induced residual stresses in order to be compliant with safety requirement of power plant. The longitudinal and transversal residual stresses in dissimilar material butt joints of 8 mm thick for V-groove shape were studied. The developed thermo-mechanical FE model as well as the simulation procedures are detailed and results are discussed. As a result of such work, it has been found out that residual stresses in the two dissimilar plates are characterized by very different magnitudes and distribution.

Deslizamiento Las Torres, volcán Irazú, Costa Rica: definición de su volumen y su dirección preferencial de movimiento

Se ha efectuado un estudio de inestabilidad de laderas en el sector oeste del volcán Irazú, el cual comprende la definición de un marco geomorfológico, la aplicación de la técnica de elementos finitos conocida como reducción de la resistencia al corte, para analizar la estabilidad del sector definido como en proceso de desestabilización y la definición del volumen de material potencialmente deslizable. El Deslizamiento Activo Río Sucio Oeste (DARSO) se identificó como el único deslizamiento activo en el sector estudiado. Adicionalmente, se ha establecido que el Deslizamiento Inactivo Retes (DIR) muestra evidencias de reactivación en el sector de su escarpe principal. Por otra parte, no se espera que la geoforma DSPD presente un movimiento hacia el suroeste en el futuro y las deformaciones mostradas por el modelo de un desprendimiento hacia el noroeste se tornan significativas una vez que a las propiedades de resistencia al corte se les aplica un factor de reducción de 1,30; desarrollándose el colapso de la ladera en una dirección de deslizamiento hacia el noroeste. Si se considera que el factor de seguridad es de alrededor de 1,30, se debe contar con un factor de disparo para que el deslizamiento se desarrolle. Finalmente, el volumen del deslizamiento se estima en 7 millones de metros cúbicos.

3D numerical models for reinforced concrete components

Application of Finite Element techniques of RC structures has been well established. However, this area still needs more research, because of the difficulty of modeling concrete in finite element analysis. Aim of this work is to develop a numerical approach based on the finite element formulation of three dimensional reinforced concrete beams. Concrete is modeled using twenty seven node brick lagrangian element. Bars and bond slip of the bar and concrete were modeled together by introducing the three dimensional truss-linkage elements. The validity of the model is established using comparison of the results with several well-known tests from the literature.

Finite element analyses and simulations of gears and gear drives

PurposeThe finite element method (FEM) has become the prevalent technique used for analyzing physical phenomena in the field of structural, solid and fluid mechanics. The output of scientific papers is fast growing and professionals are no longer able to be fully up‐to‐date with all the relevant information. The purpose of this paper is to provide a bibliographical review on the application of FEM in mechanical engineering, specifically for the analyses and simulations of gears and gear drives from the theoretical as well as practical points of view.Design/methodology/approachThe following topics on gears and gear drives are handled from the computational points of view: gears in general, spur gears, helical gears, spiral bevel and hypoid gears, worm gears and other gear types and gear drives. The paper is organized into two parts. In the first one each topic is handled in a short text, relevant keywords are presented and current trends in applications of finite element techniques are briefly mentioned. The second part lists references of papers published for the period 1997‐2006.FindingsThis bibliography is intended to serve the needs of engineers and researchers as a comprehensive source of published papers on design, analysis and simulation of gears and gear drives.Originality/valueThe bibliography listed is by no means complete but it gives a comprehensive representation of different finite element applications on the subjects. It will save time for readers looking for information dealing with described subjects, not having an access to large databases or willingness to spend time with uncertain information retrieval.

The application of advanced modelling techniques for long products rolling

The application of finite element techniques to modelling the long products rolling process, the use of a customized interface to enable the rapid set-up of sequential simulations, and the benefits that have been obtained are described. The paper also discusses the enhancements to incorporate a design of experiments/design optimisation module and to enable material tracking.

Corrosion Electrochemistry of Fuel Element Materials in Pond Storage Conditions

Magnox clad nuclear fuel elements are subject to aqueous storage following discharge from reactor. The integrity of the clad is imperative in avoiding undesirable release of soluble fission products. The corrosion performance of the material is important and pond chemistry is closely controlled to maintain passivity and prevent clad penetration. In order to allow optimization of operating chemistry and hence minimize corrosion, the aqueous corrosion behaviour of commercial magnesium alloy Magnox Al80 has been studied with the use of modern electrochemical techniques. The conventional methods employed in historical corrosion investigations, such as weight loss and hydrogen evolution, are often insensitive to certain mechanisms and require significant time-scales. Here the use of electrochemical noise and impedance spectroscopy alongside DC polarization has allowed the study of general and localized corrosion, notably clad pitting, with greatly enhanced sensitivity and reduced time-scales. Magnox corrosion has proved to be a complex and dynamic system and the formation of a passive layer and propensity to subsequent breakdown are dictated by various environmental factors, including pH, anion concentration and inhibition. This has demanded the development and application of novel techniques and real time observations of pitting initiation and propagation have been made. Empirical models have been formulated from experimental data allowing prediction of the onset of localized corrosion and the application of finite element techniques for deterministic prediction is proposed.

Finite element analyses and simulations of sheet metal forming processes

Sheet metal forming is a process of shaping thin sheets of metal by applying pressure through male or female dies or both. In most of used sheet‐formating processes the metal is subjected to primarily tensile or compressive stresses or both. During the last three decades considerable advances have been made in the applications of numerical techniques, especially the finite element methods, to analyze physical phenomena in the field of structural, solid and fluid mechanics as well as to simulate various processes in engineering. These methods are useful because one can use them to find out facts or study the processes in a way that no other tool can accomplish. Finite element methods applied to sheet metal forming are the subjects of this paper. The reason for writing this bibliography is to save time for readers looking for information dealing with sheet metal forming, not having an access to large databases or willingness to spend own time with uncertain information retrieval. This paper is organized into two parts. In the first one, each topic is handled and current trends in the application of finite element techniques are briefly mentioned. The second part, an Appendix, lists papers published in the open literature. More than 900 references to papers, conference proceedings and theses/dissertations dealing with subjects that were published in 1995‐2003 are listed.

Application of domain integral methods using tetrahedral elements to the determination of stress intensity factors

With the development of CAD packages which can create complicated 3D models and “automatically” mesh them with tetrahedral elements, the application of finite element techniques in mechanical design has reached unprecedented proportions. However, the extension of these techniques to fracture mechanics studies is hindered by the unavailability of a general method to obtain fracture mechanics singularity strength ( J, K I , etc.) for tetrahedral meshes. An approach to obtain these parameters along a 3D crack-front using tetrahedral elements is presented here. The method is then validated on well-known crack geometries, using tetrahedral meshes generated from commercially-available CAD–FEA packages.

Brake disc hot spotting and thermal judder: an experimental and finite element study

The paper covers the development and application of finite element techniques to thermo-mechanical in braking and brake disc hot judder. After a brief review of the phenomena of thermo-mechanical in braking and disc thermal judder, this paper describes and analyses experimental results of hot judder testing carried out on a dynamometer. Development of axisymmetric and 3D thermo-mechanical FE models capable of dealing with localised heat generation and wear is then described, with examples to illustrate their application to hot judder simulation. Through use of the 3D thermo-mechanical simulation together with the detailed analysis of experimental results, it is found that the out-of-phase thermoelastic buckling instability is a significant factor causing hot spotting and hot judder. This new finding contributes to the fundamental understanding of the phenomena and widens the scope to improve the brake system performance in the relevant aspects.

Mathematical Model of the Distribution of Stress within a Rice Kernel from Moisture Adsorption

A review of applications of finite element techniques in the calculation of stress distributions in grain kernels during moisture desorption and adsorption is given. In the analysis presented in this paper, the rice kernel was assumed to be a linear viscoelastic ellipsoid body. The model simulated the expansion of the rice kernel and evaluated the magnitude of the local strains and stresses. The finite element method was used to obtain a numerical solution to the stress–strain relationship. For determining fissure initiation and propagation, the failure criterion based on local strain energy density of distortion was used. For stress analysis, the maximum or ultimate tensile strength criterion was used. Simulations resulting from the model were compared with the experimental results.

Calculations of reactances in synchronous generators

The finite element (FE) method is nowadays the most popular tool for the analysis of magnetic field distributions in electric machinery. Such a distribution alone is usually not sufficient for real life applications ‐ the values of equivalent parameters for particular devices are often the main point of interest. In synchronous machines the knowledge of reactances’ values, both for steady and transient conditions, enables the calculations of most of exploitation relationships. The application of FE technique substantially helps to overcome the well known difficulties concerning the representation of geometry details, magnetic saturation and eddy current reaction, if it appears. Simultaneously, the presented way of analysis is linked with commonly used measurement methods of synchronous generators. The example calculations were done for the 150kW synchronous generator having non‐integer number of slots per pole and phase.

A simplified approach to evaluating the thermal behaviour of surface engineered cutting tools

It is commonly accepted that both the wear and failure mechanisms which develop in cutting tools are predominantly influenced by temperature. In order to predict the wear and failure characteristics of a tool it is necessary to quantify the temperatures which develop during the cutting operation. In recent years, numerical calculating methods have been widely developed in most areas of engineering and have been used to determine the thermal behaviour of cutting tools. In general, the application of finite element and finite difference techniques has been successful, yet still relies heavily on the accuracy of experimentally determined boundary conditions. If, however, for a given application, an approximate solution were all that was required to give an indication of the thermal behaviour, then a simplified approach could be applied which would realise savings of time, money and would broaden the potential user base. The development of such a technique to determine the thermal behaviour of cutting tools is described, with particular reference to assessing the thermal behaviour of single- and multi-point cutting tools before and after the application of advanced surface engineered treatments. An extensive programme of empirical and analytical work has been undertaken at Sheffield Hallam University to study the performance, life and design characteristics of various standard and surface engineered single- and multi-point cutting tools. Data acquired from research programmes have been used to predict the temperatures generated along the tool/chip interface using standard analytical methods. A simplified application of finite element techniques has been used to simulate the mode of dissipation of this heat source. The current paper describes the approach with reference to TiN-coated and standard production indexable inserts (single-point tool) and bandsaw teeth (multi-point cutting tool).

On the application of finite element techniques in the displacement compatibility method

The displacement compatibility method was used by Poe, Swift and others, to evaluate the stress intensity factor in stiffened panels with cracks. In the displacement compatibility method as they used it, the deformations of both the skin and the stiffening elements have been defined with flexibility matrices. In this paper, the governing equations are modified such that the stiffener deformations are described with a stiffness matrix. For the stiffeners, it is more convenient to use a stiffness matrix than a flexibility matrix. The stiffness matrix can be defined with finite element techniques, allowing a wider range of options to model the stiffeners. Such options include the modelling of the finite width of stiffeners, plastic deformations and geometrically non-linear deformations. It is shown that the solution obtained with the modified governing equations is identical to the solution of Poe and Yeh for elastic panels, and comparable to the solution of Creager and Liu for panels with perfectly plastic strips. The computer time required to solve the modified equations is not increased significantly, compared to the original equations. As an example of an application of the modified equations, Creager and Liu's panels have been analysed using the net-section yield failure model of Gunther and Wozumi for riveted stiffeners. In the present modified governing equations, the stiffeners might retain their complexity known from a full finite element analysis, without significantly increasing the computer time required for a parametric study.

Vibrations of Planar Curved Beams, Rings, and Arches

This work attempts to organize and summarize the extensive published literature on the vibrations of curved bars, beams, rings and arches of arbitrary shape which lie in a plane. In-plane, out-of-plane and coupled vibrations are considered. Various theories that have been developed to model curved beam vibration problems are examined. An overview is presented of the types of problems which are addressed in the literature. Particular attention is given to the effects of initial static loading, nonlinear vibrations and the application of finite element techniques. The significantly different frequencies arising from curved beam theories which either allow or prevent extension of the centerline during vibratory motion are shown. An extensive bibliography of 407 relevant references is included.

Some elevated temperature mechanical properties of Magnox AL80: Lin, Y.P. and Smith, G.C. J. Mater. Sci. Dec. 1988 23, (12), 4450–4462

Magnox clad nuclear fuel elements are subject to aqueous storage following discharge from reactor. The integrity of the clad is imperative in avoiding undesirable release of soluble fission products. The corrosion performance of the material is important and pond chemistry is closely controlled to maintain passivity and prevent clad penetration. In order to allow optimization of operating chemistry and hence minimize corrosion, the aqueous corrosion behaviour of commercial magnesium alloy Magnox Al80 has been studied with the use of modern electrochemical techniques.The conventional methods employed in historical corrosion investigations, such as weight loss and hydrogen evolution, are often insensitive to certain mechanisms and require significant time-scales. Here the use of electrochemical noise and impedance spectroscopy alongside DC polarization has allowed the study of general and localized corrosion, notably clad pitting, with greatly enhanced sensitivity and reduced time-scales.Magnox corrosion has proved to be a complex and dynamic system and the formation of a passive layer and propensity to subsequent breakdown are dictated by various environmental factors, including pH, anion concentration and inhibition. This has demanded the development and application of novel techniques and real time observations of pitting initiation and propagation have been made. Empirical models have been formulated from experimental data allowing prediction of the onset of localized corrosion and the application of finite element techniques for deterministic prediction is proposed.

Finite element analysis in combustion phenomena

AbstractThis paper is concerned with the exposition of finite element applications to combustion problems. The subject of computational fluid dynamics, including combustion calculations, has long been dominated by finite differences. Recently, however, the finite element method has emerged as a potential candidate for computational modelling in fluid mechanics. It is well known that reactive fluids with combustion present additional complications because of disparity in reaction rates commonly referred to as ‘stiff’. The present paper reviews basic questions arising from combustion problems in applications of finite element techniques to the solution of problems associated with chemical kinetics, diffusion, waves, convection, etc. Finally, an example of a hydrogen‐oxygen reaction is presented for practical applications. Extension to the finite element modelling of turbulence, sprays, boundary layers, shock waves, etc. in combustion must await significant developments of numerical strategies associated with a more complete understanding of physical phenomena and chemical kinetics.

An application of finite element technique or solving B.P.L equations

In order to solve the differential equations of meteorological parameters finite difference method is used and fed to computers. In this paper finite element technique is used for the present result the solution of atmospheric planetary boundary layer (PBL) equations. The results obtained by this solution, such a technique are comparable in accuracy with those obtained by finite difference method.

Finite element analysis of reinforced and prestressed concrete structures including thermal loading

This paper describes the application of finite element techniques to the solution of nonlinear concrete problems. Reinforced concrete thick plates and shells are first considered for which both a perfect and strain-hardening plasticity approach are employed to model the compressive behaviour. A dual criterion for yielding and crushing in terms of stresses and strains is considered, which is complemented with a tension cut-off representation. Degenerate thick shell elements employing a layered discretisation through the thickness are adopted and both reduced and selectively integrated 8-node serendipity and heterosis elements are considered. Thermal loading of prestressed concrete structures is also considered which necessitates the inclusion of time effects in the analysis. The technique described in this paper involves concurrently solving an uncoupled set of equations within a time interval to provide both the displacement and temperature increments. A two-level time stepping scheme is employed to predict temperature changes within a time interval and elasto-viscoplastic material analysis is performed using an explicit forward-difference scheme incorporating an equilibrium iteration procedure. The constitutive model for the concrete is essentially identical to that employed for the plate and shell analysis. Numerical examples are presented for both types of analysis and comparison is made with experimental results whenever possible. Additionally, results for thermal loading are presented which indicate that a full transient thermal-mechanical analysis is sometimes essential in order to obtain a realistic structural response.