Rozprawy doktorskie: „Finite element - Humanbody model”

1

Murdoch, Brian. "Finite element-CAD integrated BOD model". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0005/MQ30525.pdf.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

2

Rompré, Stéphane. "Finite element model of wood fibres". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64106.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

3

Bermejo-Bermejo, Rodolfo. "A finite element model of ocean circulation". Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26166.

Pełny tekst źródła

Streszczenie:

Preliminary results of a two-layer quasi-geostrophic box model of a wind-driven ocean are presented. The new aspects of this work in relation with conventional eddy models are a finite element formulation of the quasi-geostrophic equations and the use of no-slip boundary condition on the horizontal solid boundaries. In contrast to eddy resolving models that utilize free-slip boundary conditions our results suggest that the obtention of ocean eddies with the no-slip constraints requires a more restricted range of parameters, in particular much lower horizontal eddy viscosity eddy coefficients AH and higher Froude numbers F₁ and F₂. We show explicitly that a given range of parameters, which is eddy generating when the free-slip boundary condition is used, leads to a quasi-laminar flow in both, upper and lower, layers. An analytical model to interpret the numerical results is put forth. It is an extension of an earlier model of Ierley and Young (1983) in that the relative vorticity terms are of primary importance for the dynamics. Thus, it is shown that the boundary layer dynamics is active in the interior of the second layer, and it can be concluded from our method that for given F₁ and F₂ such that the lower layer geostrophic contours are closed, to the existence of the western boundary layer will prevent the homogenization of the potential vorticity so long as AH is large enough to stabilize the northwestern undulations of the flow.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

Style APA, Harvard, Vancouver, ISO itp.

4

Yin, John Zhihao. "Finite element model of cardiac electrical conduction". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/26859.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

5

Gotin, Nathalie. "Finite Element Model Updating for Rotary Machinery". DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/864.

Pełny tekst źródła

Streszczenie:

The main approach of this thesis was to develop a mathematical model that represents a rotary machine. Experimental data was used to define a finite element model (FEM). In order to obtain the experimental data, the rotary machine had to be balanced. An impact hammer test made it possible to obtain frequency response functions (FRF). The frequency response functions were curvefitted in order to obtain the mode shapes and natural frequencies. Mathematical models have been created with ABAQUS and Matlab. For the Matlab Model the assumption has been made that the rotor machine consists of a specific number of beam elements. The FEM matrices have been reduced with the Guyan Reduction Method to coincide with the DOFs of the experiment. Applying the method of the least square to an Error Function made it possible to obtain new values for the stiffness and damping of the bearings (). This made it possible to update the mathematical model. By applying the Model Assumption Criterion the theoretical model and those detected from the experimental measurement could be validated. The correlation for Mode Shapes 1 could be improved from 0.6647 to 0.8186 and for Mode Shape 2 from 0.0209 to 0.4208. Therefore, the created method could be proven to work. Additionally the whole theory has been validated with a very simplified model.

Style APA, Harvard, Vancouver, ISO itp.

6

Wilson, Kelly A. "Finite Element Analysis of Breast Implants". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/32972.

Pełny tekst źródła

Streszczenie:

The Breast Implant Lifetime Study at Virginia Tech, on which this thesis is based, seeks to develop methods and data for predicting the lifetime of saline-filled implants. This research developed Finite Element Analysis (FEA) models to evaluate the stresses that are present in the silicone breast implant material under different loading situations. The FEA work was completed using the commercial codes PATRAN and ABAQUS. PATRAN was used for pre- and post-processing, while ABAQUS was used for the actual analysis and to add fluid and contact elements not supported by PATRAN. Many different loading situations and constraints were applied to these models, as well as variations in the material and model properties. Varying the Poisson's ratio of the implant material from 0.45 to 0.49 did not make a significant difference in the results. Changing the elastic modulus of the implant material from the modulus of a Smooth implant to the modulus of a Siltex implant had a noticeable effect on the stress results, increasing the maximum stresses by almost 8%. Changing the modulus of the surrounding tissue had marked effects as well, with stiffer tissue (E=300 psi) decreasing the implant's stresses by about 60% as compared to softer tissue (E=100 psi). A ten percent decrease in implant thickness yielded a 17% average increase in stress experienced by the implant. For both the 2.5" radius and the 4" radius tissue models, using CAX4 elements produced higher overall stresses in the tissue with the same loading conditions. However, in the 2.5" tissue model, the implant itself experienced less stress with the CAX4 tissue than the CAX3 tissue. In the 4" tissue model, the implant experienced more stress when surrounded by the CAX4 tissue elements. These models will be combined with implant fatigue data to develop a life prediction method for the implant membrane.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

7

Codina, Rovira Ramon. "A finite Element model for incompressible flow problems". Doctoral thesis, Universitat Politècnica de Catalunya, 1992. http://hdl.handle.net/10803/5915.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

8

Le, Roux Daniel Y. "A semi-Lagrangian finite element barotropic ocean model". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ44492.pdf.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

9

Levin, Robert Ian. "Dynamic Finite Element model updating using neural networks". Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264075.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

10

Waters, Timothy Paul. "Finite element model updating using frequency response functions". Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294617.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

11

Terrell, Michael John. "Constrained generic substructures in finite element model updating". Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430175.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

12

Gorman, John P. (John Patrick) 1973. "Finite element model of thermoelastic damping in MEMS". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8458.

Pełny tekst źródła

Streszczenie:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002.
Includes bibliographical references (p. 111).
Damping in MEMS resonators was studied experimentally and numerically. Quality factor measurements were performed on Draper gyroscopes made from boron doped silicon wafers with varying amount of germanium (0%, 2%, 23%, 30% ). The quality factors of gyroscopes with germanium were measured to be lower than those without germanium, due to increased anelastic damping. Specifically, the decreased thermal conductivity in the devices with germanium causes those devices to experience thermoelastic damping of a greater magnitude than the germanium-free devices. The amount of damping exhibited is found to be well explained by existing analytical expressions for thermoelastic dissipation in a beam model. The governing equations of thermo elasticity dictate that the amount of damping that a resonator undergoes is a function of both material properties as well as device geometry. Damping will become greatest at operating cycle times that are of the same scale as the thermal relaxation times of the device material. Due to the fact that analytical expressions exist for only a few simple geometries, a finite element model was developed to evaluate thermoelastic damping in more complicated geometries. The finite element model is demonstrated to be in good qualitative agreement with the analytical expressions, and is used to analyze the impact of design modifications such as the addition of fillets and anchors to a simple beam model. It is shown that depending on the size scale of the resonator (which dictates the amount of internal damping), these geometric modifications may either hinder or improve resonator damping characteristics.
by John P. Gorman.
S.M.

Style APA, Harvard, Vancouver, ISO itp.

13

Eriksson, Daniel. "A Mass Conserving Wind Model Evaluation With Finite Element". Thesis, Umeå universitet, Institutionen för fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-80406.

Pełny tekst źródła

Streszczenie:

This work describes a method of approximating a wind field for an urban environment for the purpose of dispersion modelling. Instead of using the classic Navier Stokes equation, a mass conserving wind model is evaluated. The model uses an empirical diagnostic study to approximate a stationary windfield that is forced to be convergence free using a least square variational technique. This work has shown that there is a way to approximate the mass conserving wind field for a large urban environment using Comsol Multiphysics and the Finite Element Method. Compared to wind tunnel experiment the large features of the main flow are present but the wind speed is underestimated. Among the iterative solvers tested Multi grid and Conjugate Gradient performed best. An urban city with 2 100 000 degrees of freedom had a solution time of around three minutes.
Detta arbete testar och utvärderar en metod for att approximera ett stationärt vind fält i en urban miljö i syfte att användas for spridnings beräkningar. Istället for att använda Navier Stokes ekvation används en massbevarande modell. Denna modell använder empirisk information for att approximera vind fältet. Fältet görs sedan massbevarande. Detta arbete visar att det ar möjligt att lösa modellen med Finita Element och Comsol Multiphysics för stora urbana miljöer på kort tid. Jämförelser med vindtunnel experiment visar att de stora virvlarna är synliga men att hastigheterna är lägre. Bland de iterativa lösarna som användes presterade Multigrid och Conjugat Gradient metoden bäst. En urban miljö med 2 100 000 frihetsgrader hade en lösningstid på ca 3 minuter.

Style APA, Harvard, Vancouver, ISO itp.

14

Giavaras, Alexandros. "A finite element model for the permeability of textiles". Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546289.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

15

Mercer, Judith F. "Containment of the spacecraft finite element model correlation process". Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/842377/.

Pełny tekst źródła

Streszczenie:

Mathematical finite element models (FEMs) of spacecraft are relied upon for the prediction of loads experienced during launch and flight events. It is essential that the spacecraft is able to survive the launch environment without sustaining damage which could inhibit its ability to carry out its mission. Therefore, ensuring that these FEMs give a realistic representation of the physical spacecraft structural dynamics is an important task. To achieve a high level of confidence in the FEM in question, a correlation activity is conducted. This is the process of applying various metrics to compare computational results, from analysis of the FEM, with corresponding data derived from measurements taken of the physical hardware during vibration testing. Subsequently, updates are applied to the FEM where necessary to achieve an acceptable level of correlation. It is possible for spacecraft FEM correlation exercises to take a considerable amount of time and effort without necessarily achieving an appreciable improvement in the final FEM. As such, this project has been conducted to address the need to ensure that the procedures being applied are as effective and efficient as possible. Various aspects of the spacecraft FEM correlation process have been investigated separately, and interactions between the different stages in the process have also been considered. Two large, unique, scientific spacecraft have been used as example applications in order to carry out these studies. As well as making use of computational results from the spacecraft FEMs, this project has also included comparisons to the results from the corresponding base-shake sine-sweep test campaigns conducted on these structures. A number of noteworthy, and industrially beneficial, findings relating to the effectiveness of the spacecraft FEM correlation process have resulted from these studies: the most appropriate techniques of modal parameter estimation for the considered spacecraft applications have been established; the potential benefits and relative merits of different pre-test sensor placement procedures have been explored; inaccuracies introduced through the use of a commonly applied FEM reduction method have been demonstrated and a superior alternative identified. In addition, the efficiency of the correlation and update process has also been addressed. This has mainly been achieved through investigations concerning the applicability of commonly used target mode selection criteria to spacecraft applications, and the potential benefits of a less widely applied method which takes into consideration the expected loading scenarios to be experienced by the considered structures.

Style APA, Harvard, Vancouver, ISO itp.

16

Hamiche, Karim. "A high-order finite element model for acoustic propagation". Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/400677/.

Pełny tekst źródła

Streszczenie:

Sound propagation in complex non-uniform mean flows is an important research area for transport, building and power generation industries. Unsteady flows are responsible for noise generation in rotating and pulsating machines. Sound propagates in ducts and radiates through their openings. Duct discontinuities and complex flow effects on acoustic propagation need to be investigated. Although it provides accurate results, the most commonly used Computational AeroAcoustics propagation method, the full potential theory, does not describe the whole physics. Turbofan exhaust noise radiation involves strong refraction of the sound field occurring through jet shear layer, as well as interaction between the acoustic field and the vorticity/entropy waves. The Linearised Euler Equations are able to represent these effects. Solving these equations with time-domain solvers presents shortcomings such as linear instabilities and impedance modelling, which can be avoided by solving in the frequency domain. Nevertheless the classical Finite Element Method in frequency domain suffers from dispersion error and high memory requirements. These drawbacks are particularly critical at high frequencies and with the Linearised Euler Equations, which involve up to five unknowns. To circumvent these obstacles a novel approach is developed in this thesis, using a high-order Finite Element Method to solve the Linearised Euler Equations in the frequency domain. The model involves high-order polynomial shape functions with unstructured triangular meshes, numerical stabilisation and Perfectly Matched Layers. The computational effort is further optimised by coupling the Linearised Euler Equations in the regions of complex sheared mean flow with the Linearised Potential Equation in the regions of irrotational mean flow. The numerical model is applied to aeroengine acoustic propagation either by an intake or by an exhaust. Comparisons with analytic solutions demonstrate the method accuracy which properly represents the acoustic and vorticity waves, as well as the refraction of the sound field across the jet shear layer. The benefits in terms of memory requirements and computation time are significant in comparison to the standard low-order Finite Element Method, even more so with the coupling technique.

Style APA, Harvard, Vancouver, ISO itp.

17

Ahsan, Nabeel. "OCTG Premium Threaded Connection 3D Parametric Finite Element Model". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71791.

Pełny tekst źródła

Streszczenie:

Full 360 degree 3D finite element models are the most complete representation of Oil Country Tubular Goods (OCTG) premium threaded connections. Full 3D models can represent helical threads and boundary conditions required to simulate make-up and service loading. A methodology is developed to create a 360 degree full 3D parametric finite element model with helical threads as an effective design and analysis tool. The approach is demonstrated with the creation of a metal-to-metal seal integral joint full 3D model with manufacturer supplied geometry. The premium connection is decomposed into smaller parts to generate parametric geometric features. A controlled parametric meshing scheme is developed to manage mesh density in contact regions to effectively represent the mechanics in regions of interest while minimizing total element count. The scripted parametric approach allows for efficient geometric and mesh updates. Several methods to reduce and manage model runtimes are presented. An elastic-plastic material model is created with material coupon tensile tests results. Digital Image Correlation (DIC) is used to measure full-field displacement and strain data on the surface of the box. Experimental set up and data processing procedures are discussed. Error metrics are developed to correlate the finite element model results with the DIC experimental data. The DIC make-up experimental results are used to reconcile the finite element model to develop a minimum error make-up model relative to the pin rotation. The friction coefficient is estimated and the make-up torque-turn behavior is verified. The calibrated 3D finite element model is validated with ISO_13769 load series B axial and internal pressure loading experimental DIC data. Metal-to-metal seal metrics of contact pressure and seal length are evaluated.
Master of Science

Style APA, Harvard, Vancouver, ISO itp.

18

LaPeter, Christina M. "Application of distributed measurements for finite element model verification". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12302008-063220/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

19

Ren, Zhen. "Modular model assembly from finite element models of components". Diss., Connect to online resource - MSU authorized users, 2008.

Znajdź pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

20

Adolfsson, Erik. "Simplified finite element bearing modeling : with NX Nastran". Thesis, Uppsala universitet, Tillämpad mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255398.

Pełny tekst źródła

Streszczenie:

This report was produced at the request of ABB Robotics and the work was conducted at their facilities in Västerås, Sweden. In the development of industrial robots the structures are slimmed to increase the accuracy and speed. When conducting finite element analysis on the robots the accuracy of the component modelling and definitions of the boundary conditions becomes more important. One such component is the ball bearing which consist of several parts and has a nonlinear behavior where the balls are in contact with the rings. The task given was to develop new methods to model roller bearings in Siemens finite element modelling software NX Nastran. Then conduct a strain measurement, to compare the methods to real experimental values. The goal with the report is to find one or more methods to model roller bearings, with accurate results, that can beused in their development work. The report was conducted by first doing a study on bearings and finite element modeling, and learning to use the software NX Nastran. Then the development of the methods were done by generating ideas for bearing models and testing them on simple structures. Nine methods was produced and a tenth, the method used to model bearings today, was used as a reference. The methods was used to build bearing models in a finite element model of a six axis robot wrist. Simulations were done on the models with different load cases and the results were compared to a strain measurement of the wrists real counterpart. Only six of the models were analyzed in the result, since four of the models returned results that were deemed unusable. When compiling the result data no model was found to accurately recreate the stresses in every load case. Three methods, that allow deformation, performed similarly. One of them is suggested to be used as modelling method in the future. Worst of the methods, according to the results compiled, was found to be the method used today. It fails to describe local stresses around the bearing. For continued work it is suggested that linear contact elements is studied further. Four out of five models constructed with linear contact elements failed to return satisfactory results.

Style APA, Harvard, Vancouver, ISO itp.

21

Subramaniam, Hari. "VIBRATION ANALYSIS OF CARBON NANOTUBE USING CONTINUUM MODEL AND FINITE ELEMENT MODEL". Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2268.

Pełny tekst źródła

Streszczenie:

The main objective of the thesis is to propose the methods of determining vibration behavior of carbon nanotubes (CNTs) using continuum models and finite element models. Secondary objective is to find the effect of van der Waals force on vibration of multiwalled carbon nanotubes . The study of vibration behavior of CNTs is important because of their potential engineering applications such as nano-mechanical resonators and tips of scanning probe instruments where they are subjected to mechanical vibrations. Continuum modeling is based on an elastic beam model. The interlayer van der Waals interactions are represented by Lennard-Jones potential. In finite element modeling, single walled nanotubes (SWNTs) are modeled as finite beam elements and multi-walled nanotubes (MWNTs) as finite solid elements. The interlayer van der Waals interactions are simulated by distributed springs. The proposed finite element approach and continuum approach for vibration analysis of CNTs are verified by comparing the results with experimental and analytical results available in the literature. The results from both continuum and finite element modeling show that the effect of van der Waals force on vibration of MWNTs are high for smaller aspect ratios irrespective of boundary conditions and number of layers; fixed nanotube than cantilever nanotube for the same dimensions ; five-walled nanotube than a double walled nanotube for the same aspect ratio.
M.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering

Style APA, Harvard, Vancouver, ISO itp.

22

Kwok, C. M. "Finite element studies of reinforced embankments on soft ground". Thesis, University of Sheffield, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382420.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

23

Iolov, Alexandre. "Finite element methods for a microstructure-based model of blood". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28306.

Pełny tekst źródła

Streszczenie:

The goal of this thesis is to solve numerically the equations for viscoelastic fluid flow that arise from a model of human blood. The model accounts for the elastic stress acting on the flow using a microstructure variable which itself depends on the flow. The resulting coupling offers a challenging numerical problem which however is capable of reproducing experimental results. This work implements a general Finite Element Code for solving the equations of motion, stress and microstructure state. Our work sought to validate the numerical scheme in two geometries, coaxial cylinders and a flat channel, and to further explore the model under a pulsatile flow regime in a non-trivial geometry -- a dilated channel.

Style APA, Harvard, Vancouver, ISO itp.

24

Taylor, Thomas Alan. "A finite element based model of gas/liquid mechanical seals". Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17027.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

25

Daniel, Sam J. "Finite-element model of the human eardrum and middle ear". Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29429.

Pełny tekst źródła

Streszczenie:

Computer-generated models are increasingly being used in otolaryngology for teaching purposes, pre-operative planning and clinical simulations, especially when dealing with small complex areas such as the middle ear.
One technique used to analyse the mechanics of complex models is the finite-element method whereby the system of interest is divided into a large number of small simple elements. The mechanical properties and applied forces are represented by functions defined over each element, and the mechanical response of the whole system can then be computed.
A unique three-dimensional finite-element model of the human eardrum and middle ear was devised. This model takes advantage of phase-shift moire shape measurements to precisely define the shape of the eardrum. The middle-ear geometry is derived from histological serial sections and from high-resolution magnetic-resonance microscopy of the human ear.
The model allows an improved understanding of the mechanics of the human middle ear, can simulate various pathological conditions, and assist in the design of ossicular prostheses.

Style APA, Harvard, Vancouver, ISO itp.

26

Chau, Kam Shing Patrick. "A finite element model for stress analysis of underground openings /". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63962.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

27

Khodaparast, Hamed Haddad. "Stochastic finite element model updating and its application in aeroelasticity". Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548785.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

28

Gasson, Paul David. "A finite element model of human skin for surgical simulation". Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502554.

Pełny tekst źródła

Streszczenie:

In this thesis, a finite element model of human skin is proposed for use in an interactive real-time surgical simulation to teach surgeons procedures such as facial reconstruction using skin flap repair. For this procedure, skin is cut into flaps that are stretched and rotated to cover openings in the face. Thus, the model must recreate the visual and haptic feedback expected by the surgeon. To define the model, a series of experiments were conducted on samples of human skin that were tested in vitro and subjected to uniaxial and planar tensile straining. Hyperelastic materials were then fitted to the stress-strain data produced. Reduced polynomial hyperelastic materials of third to sixth order were found to fit many of the samples' stress responses well. Viscoelastic materials were not considered due to their higher computational complexity and simulation requirements. An explicit dynamic finite element mesh was developed based on the fitted reduced polynomial hyperelastic materials. A total-Lagrangian formulation was used and th.e half-step central difference method was employed to integrate the dynamic equation of motion of the mesh. The mesh was integrated into two versions of a real-time skin simulator: a single-threaded version running on a computer's main central processing unit and a muli-threaded version running on a computer's graphics card. The latter is achieved by exploiting recent advances in programmable graphics technology. The simulator produced stress responses similar to those found by a comercially available finite element analysis package (ABAQUS explicit). Results also matched the skin experiments' data closely (R2 ~ 0.975). The performance of the simulator was also assessed and the multi-processor version proved capable of simulating a mesh of 10000 tetrahedral elements (representing a patch of 44 x 44 x 1 mm sized skin) at 3788 Hz, a rate sufficient for real-time simulation.

Style APA, Harvard, Vancouver, ISO itp.

29

Cooper, Edward. "An elastic-plastic finite element model for composite crash structures". Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268468.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

30

Than, Soe Muang. "Vibration-based finite element model updating and structural damage identification". Thesis, University of Greenwich, 2013. http://gala.gre.ac.uk/11451/.

Pełny tekst źródła

Streszczenie:

Damage and material deterioration could lead to structural failure with unknown consequences. Structural health monitoring strategy based on vibration measurements for existing aging structures offers a promising technique for effectively managing the deteriorating structures. The main objectives of this research are to develop a procedure for finite element model updating by using incomplete modal data identified from vibration measurements, to develop real time structural damage detecting method by directly using vibration measurements and then identify the damage at detailed location and extend in the structure on the basis of the validated numerical model. A steel frame model structure was constructed in the laboratory for finite element model updating and structural damage detection. Forced vibration testing was undertaken on the model structure and dynamic response such as accelerations were measured by using sensors installed. Modal analyses are then carried out to identify modal parameters such as frequencies, mode shapes and damping from the vibration measurements. Structural damage scenarios were simulated by breaking bracing members of the model structure, and modal parameter of the damaged structures were also identified and analysed. An effective approach for directly updating finite element model from measured incomplete modal data with a regularised iterative algorithm is then presented. The exact relationship between the perturbation of structural parameters and the modal properties of the dynamic structure is developed. Numerical simulation investigations and experimental study of a laboratory tested space steel frame model and practical application to the Canton Tower benchmark problem are undertaken to verify the accuracy and effectiveness of the proposed model updating method. Finally, a new approach for real time structural damage detection by using acceleration measurements is presented. Structural damage is characterised at element level by introducing damage parameters which can indicate the location and severity of damage in the structure. The relationship between the damage parameters and the measured dynamic response is then established from the governing equation of the dynamic structure. Numerical examples of cantilever beams, plane frame, and braced frames are adopted to demonstrate the effectiveness of the proposed method. The new proposed technique performs well and produces stable and reliable results, which could be used for real time damage assessment during the event of earthquake and explosion.

Style APA, Harvard, Vancouver, ISO itp.

31

Kang, Jae-Sun. "A finite element continuum model for consolidation due to pumpage". Thesis, Swansea University, 2005. https://cronfa.swan.ac.uk/Record/cronfa42218.

Pełny tekst źródła

Streszczenie:

Modelling the mechanical behaviour of engineering phenomena has occupied the attention of researchers since Karl Terzaghi's pioneering work on settlement due to consolidation in 1925. Soil improvement methods using vertical drains in combination with pre-loading were used for soil stabilization at the San Francisco- Oakland Bay Bridge in 1926. Over the next decades, other drain methods, including prefabricated and pack drains, were developed and used for practical purposes. In the mid-1990s, vacuum-induced consolidation became a reliable technology, thanks to a rethinking of theoretical principles that led to the Menard vacuum system. The Menard system was used successfully, for the first time in South Korea, for construction of the Kimhae sewage treatment plant. The drain method is based on Terzaghi's one-dimensional consolidation theory and Barron's vertical drain. Even when using finite element simulation, numerical solution for consolidation problems involves averaging material properties such as elastic modulus, Poisson's ratio, and coefficients of permeability. But the results are too unreliable to use for practical purposes. Classical mechanics alone do not provide sufficient information on the global motion equation of fluid in a porous media. A new approach is presented in this paper to the problem of continuum modelling of vacuum-induced consolidation due to pumpage. This finite element continuum model uses the interior boundary condition instead of installed vacuum tube as a line, with changing pore pressures at the installed material being treated as boundary conditions of the interior part. An innovative linear equation solution method for separate fixed boundary conditions is presented. The efficacy of this model for field construction is shown by comparing results with the results obtained from field measurements at the Jangyoo sewage plant. Because the properties of material are not exact in their natural states, the results of the calculated finite modelling are similar but not a mirror image of field measurements. Whereas conventional one-dimensional calculation uses only one point, the finite element continuum model shows displacements and pore pressures for a whole section. Once the exact material properties have been determined, the model can be applied effectively to field analyses, predicting settlements due to pumpage and facilitating decision making about when pumpage should start and stop. The finite continuum model for consolidation due to pumpage can be applied to other soil improvement methods, such as prefabricated and pack vertical drain, with some modification.

Style APA, Harvard, Vancouver, ISO itp.

32

Lee, Youngho. "Finite element model updating of loaded and geometrically modified structures". Thesis, University of Bristol, 2006. http://hdl.handle.net/1983/f7493e73-ad88-438c-8b8e-a3e801ec9947.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

33

Lesser, Beverly Brown. "Thermal-magnetic finite element model of a high frequency transformer". Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44121.

Pełny tekst źródła

Streszczenie:

In high-frequency power transformers, magnetic material properties cannot be assumed to be constant. These properties vary with frequency, temperature, and magnetic flux density. Heat generation is, in turn, a function of the magnetic permeability, magnetic flux density, and frequency. Current design methods are either empirical or based on linear, uncoupled models. To better understand the relationship between heat transfer, magnetic flux density, material properties, and core geometry in a miniature, high-frequency transformer, a finite-element program has been developed to solve the coupled thermal-magnetic equations for an axisymmetric transformer. The program accounts for nonlinear temperature and magnetic field dependent material properties, geometry, and driving frequency.

The program, HT-MAG, is based on a series of derived magnetic field equations. The Ritz method is applied to the magnetic and thermal equations in the development of the program. The program alternately solves the finite element approximations to the thermal and magnetic governing equations until the magnetic properties match within a specified fraction or a maximum number of iterations are performed. In addition, the program can be linked with existing pre- and post-processors or can accept manual pre- and post-processing.

Six test cases were run to test the validity of the program. The first two cases tested the uncoupled heat transfer calculations. One of these tested the thermal conduction calculations while the other tested the heat generation calculations. The next two cases tested the uncoupled magnetic equations. The first was a direct current (DC) case, while the second was an alternating current (AC) case. The final two cases tested the thermal magnetic coupling. Solutions to these cases are presented and discussed.

Master of Science

Style APA, Harvard, Vancouver, ISO itp.

34

Pilkey, Deborah F. "Computation of a Damping Matrix for Finite Element Model Updating". Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30453.

Pełny tekst źródła

Streszczenie:

The characterization of damping is important in making accurate predictions of both the true response and the frequency response of any device or structure dominated by energy dissipation. The process of modeling damping matrices and experimental verification of those is challenging because damping can not be determined via static tests as can mass and stiffness. Furthermore, damping is more difficult to determine from dynamic measurements than natural frequency. However, damping is extremely important in formulating predictive models of structures. In addition, damping matrix identification may be useful in diagnostics or health monitoring of structures. The objective of this work is to find a robust, practical procedure to identify damping matrices. All aspects of the damping identification procedure are investigated. The procedures for damping identification presented herein are based on prior knowledge of the finite element or analytical mass matrices and measured eigendata. Alternately, a procedure is based on knowledge of the mass and stiffness matrices and the eigendata. With this in mind, an exploration into model reduction and updating is needed to make the problem more complete for practical applications. Additionally, high performance computing is used as a tool to deal with large problems. High Performance Fortran is exploited for this purpose. Finally, several examples, including one experimental example are used to illustrate the use of these new damping matrix identification algorithms and to explore their robustness.
Ph. D.

Style APA, Harvard, Vancouver, ISO itp.

35

Deserranno, Dimitri. "A Multi-Scale Finite Element Model of the Cardiac Ventricles". Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1148984314.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

36

Baker, Edward Michael. "A finite element model of the Earth's anomalous gravitational potential /". The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588249823203.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

37

Bahadursha, Venkata Rama Lakshmi Preeethi. "Tearing of Styrene Butadiene Rubber using Finite Element Analysis". University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1431029910.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

38

Greening, Paul David. "Dynamic finite element modelling and updating of loaded structures". Thesis, University of Bristol, 1999. http://hdl.handle.net/1983/5f23c082-ba8b-4860-a81d-ca5e507fd632.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

39

Golshayan, Maryam. "A study of internal defibrillation efficacy using finite element analysis: a 3D isotropic finite element model of the myocardium electric fields". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18790.

Pełny tekst źródła

Streszczenie:

Ventricle fibrillation (VF) is a condition in which the heart's lower chambers show an unsynchronized and chaotic motion which prevents the heart from pumping blood and oxygen to the body. VF is considered a sudden cardiac arrest and it is responsible for 300,000 sudden deaths in the USA yearly. The most effective way of reversing this life threatening condition is to apply an electrical shock directly to the heart using an Implantable Cardioverter-Defibrillator (ICD). The main issue in using ICDs is the placement of the defibrillating electrodes so that the current can be optimally channeled through the cardiac muscle, particularly in the left ventricular myocardium. According to the critical mass hypothesis, defibrillation will be successful when 75% of the myocardium tissue is halted by the defibrillation shock. The defibrillation threshold (DFT) or the minimum effective voltage required for successful results is suggested to be related to the myocardial voltage gradient (VG) distribution, but it has not been quantified. Moreover, the goal is to keep the DFT as low as possible to try to maximize the success of defibrillation, minimize the chance of myocardium damage and cardiac arrhythmias caused by high-intensity shocks, and also potentially reduce the battery size and as well as prolong the device's useful lifespan. Various numerical techniques have been used to model the heart to solve the governing equations required to obtain the myocardium VG distribution during electrical defibrillation. The Finite Element Method (FEM) has been of particular interest since it can handle the irregular domains, material inhomogeneities, and complex boundary conditions of problems in bioelectricity. In this thesis, a finite element model of the heart tissue is constructed in order to study and optimize the defibrillation mechanism. The modelling process starts with a surface reconstruction based on radial basis function interpolation to generate the triangular surface me
La fibrillation ventriculaire (FV) est un état dans lequel la cavité inférieure du coeur montre une motion asynchrone et chaotique, empêchant le coeur de pomper le sang et l'oxygène au corps. La FV est considérée comme un arrêt cardiaque soudain, responsable de la mort subite de 300,000 personnes chaque année aux Etats-Unis. Afin d'inverser cette condition mortelle, le recours le plus efficace est la délivrance d'un choc électrique directement au niveau du coeur à l'aide d'un Défibrillateur Cardioverteur Implantable (DCI). Le principal problème de l'utilisation des DCIs est le placement des électrodes défibrillateurs pour permettre au courant d'être conduit optimalment à travers du muscle cardiaque, en particulier, le myocarde ventriculaire gauche. Selon l'hypothèse de la masse critique, la défibrillation sera réussi quand 75% du tissu de myocarde est inactivé par le choc de défibrillation. Le seuil de défibrillation ou la tension efficace minimale exigée pour donner des résultats réussis est suggéré d'être liés à la distribution du gradient de la tension myocardique, toutefois, il n'a pas été mesurée. En outre, le but est de maintenir le seuil de défibrillation aussi bas que possible pour essayer de maximiser le succès de la défibrillation, réduire au minimum le risque des dommages de myocarde et des arythmies cardiaques provoqués par des chocs à haute intensité, et aussi permettre de réduire la taille de la batterie ainsi que prolonger la durée de la vie utile du dispositif. De diverses techniques numériques ont été utilisées pour modeler le coeur afin de résoudre les équations régissant requises pour obtenir la distribution de gradient de la tension myocardique pendant la défibrillation. La méthode des éléments finis (FEM) a été d'intérêt particulier car elle peut gérer les domaines irréguliers, les hétérogénéité de matériel, et les conditions aux limites complexe de problèmes dans la bioélec

Style APA, Harvard, Vancouver, ISO itp.

40

Ho, Johnson. "Generation of Patient Specific Finite Element Head Models". Doctoral thesis, Stockholm : Teknik och hälsa, Technology and Health, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9585.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

41

Conradie, Johan. "Finite Element Modelling of Off-Road Tyres". Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/45957.

Pełny tekst źródła

Streszczenie:

Most tyre models developed to date require a fair amount of data before an accurate representation of the tyre can be obtained. This study entails the development of a simplified, yet accurate, non-linear Finite Element (FE) model of an “off-road” tyre to study the behaviour of the tyre due to radial loading conditions. The study aims to develop a FE tyre model that can solve fast and be accurate enough to be used in multibody dynamic vehicle simulations. A model that is less complex than conventional detailed FE models is developed. The work explores the use of superimposed finite elements to model the varying stiffness in the respective orthogonal directions of the sidewall and tread of the tyre. Non-linear elements defined by Neo-Hookean or Ogden models and elements with different linear orthogonal stiffnesses are superimposed onto each other to simulate the global material properties of the tread and the sidewall of the tyre investigated. The geometry of the tyre studied was measured experimentally using laser displacement transducers and digital image correlation techniques. Material properties of segments of the tyre were obtained by performing tensile tests on samples. Since the rubber slipped against the clamps during the experiment, deformation of the segments was also measured using digital image correlation. These geometrical and material properties were used as input to develop a finite element model of an “off-road” tyre. Measurements were conducted using laser displacement transducers, load cells mounted to actuators, etc. to obtain accurate sidewall deformation profiles and global radial load vs. displacement curves for different radial loading conditions. The data obtained from the results was used to validate the tyre model developed. Numerous analyses are performed with different combinations of moduli of elasticity in the respective orthogonal directions of the sidewall stiffness and the tread to investigate its influence on the global behaviour of the tyre model. The main focus of the project was to develop a tyre model from data obtained from laser and photogrammetry measurements in a laboratory that accurately represents tyre behaviour due to radial forces. A finite element model that can simulate the effect of radial forced and obstacles on a tyre was developed. The use of two subsets of elements, superimposed onto each other to simulate global material properties of the rubbers, steel wires, polyester and nylon threads, was investigated. The combination of material properties that gave the best fit for all the load cases investigated were determined. The finite element model correlated well with the load vs. displacement graphs and sidewall displacement profiles determined experimentally. The solving time is still fairly high and is still not quite suitable for real-time dynamic simulation. However, it solves faster than more complex tyre models where details of steel wires, etc. are included in the model. For future studies it is recommended that different element types be investigated in the tyre model. The study proves that equivalent material properties can be used to simulate the composite properties of the materials in tyres. Most tyres can be divided into a few regions that each has its own material structure right through the region. These regions can be characterized by simple tests and the input can be used as a first estimation of the tyre’s material properties for the model. Accurate validation criteria should be used to validate the tyre model if time does not allow for excessive testing of the material properties of all the rubber, steel wires, polyester threads, etc. Geometric displacement data at various loading conditions can be used for validation of the tyre model. The model developed can be used to investigate the effect of different stiffnesses and other material changes in the sidewall or tread of a tyre. Useful insight can be obtained from the finite element model developed for dynamic simulation where the force vs. global displacement data is important.
Dissertation (MEng)--University of Pretoria, 2014.
tm2015
Mechanical and Aeronautical Engineering
MEng
Unrestricted

Style APA, Harvard, Vancouver, ISO itp.

42

DeGregory, Christopher P. "Finite element model updating and damage detection using artificial boundary conditions". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA361817.

Pełny tekst źródła

Streszczenie:

Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, March 1999.
"March 1999". Thesis advisor(s): Joshua H. Gordis. Includes bibliographical references (p. 77). Also available online.

Style APA, Harvard, Vancouver, ISO itp.

43

Ozturk, Murat. "Finite Element Structural Model Updating By Using Experimental Frequency Response Functions". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610608/index.pdf.

Pełny tekst źródła

Streszczenie:

Initial forms of analytical models created to simulate real engineering structures may generally yield dynamic response predictions different than those obtained from experimental tests. Since testing a real structure under every possible excitation is not practical, it is essential to transform the initial mathematical model to a model which reflects the characteristics of the actual structure in a better way. By using structural model updating techniques, the initial mathematical model is adjusted so that it simulates the experimental measurements more closely. In this study, a sensitivity-based finite element (FE) model updating method using experimental frequency response (FRF) data is presented. This study bases on a technique developed in an earlier study on the computation of the so-called Mis-correlation Index (MCI) used for identifying the system matrices which require updating. MCI values are calculated for each required coordinate, and non-zero numerical values indicate coordinates carrying error. In this work a new model updating procedure based on the minimization of this index is developed. The method uses sensitivity approach. FE models are iteratively updated by minimizing MCI values using sensitivities. The validation of the method is realized through some case studies. In order to demonstrate the application of the method for real systems, a real test data obtained from the modal test of a scaled aircraft model (GARTEUR SM-AG19) is used. In the application, the FE model of the scaled aircraft is updated. In the case studies the generic software developed in this study is used along with some commercial programs.

Style APA, Harvard, Vancouver, ISO itp.

44

Feng, Fan. "Flutter Analysis of Stonecutters Cable-stayed Bridge using Finite Element Model". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32470.

Pełny tekst źródła

Streszczenie:

The current research analyzed the flutter response of the Stonecutters Cable-Stayed Bridge in Hong Kong, which has a twin deck configuration, under the effect of wind. The aerodynamic instability response of the bridge steel deck of the main span is mainly the focus of the current project. Initially, a complete finite element bridge model was created in ABAQUS finite element software, representing all the structural elements of the Stonecutters Cable-Stayed Bridge in a lumped mass bridge model. The natural frequencies and the vibration modes were validated against the data available in the literature at first. Secondly, the effect of the mean wind loading for wind speeds between 35 m/s and 211 m/s were determined. The vertical and horizontal displacements and the torsional angle at mid-span are indicated to determine the bridge performance under mean wind load. Moreover the flutter instability was modeled based on Scanlan’s theory and the response of the bridge model at several different locations along the main and the side span and the top of the tower, were determined for wind speeds of 35 m/s and higher, where this critical aerodynamic instability is expected to occur. In addition, the responses of the bridge under natural wind data were also determined by applying a wind speed recorded data to the bridge model. Finally, the critical flutter wind speed and the flutter frequency were determined by Fast Fourier Transform in MATLAB program. The flutter onset wind speed was also determined.

Style APA, Harvard, Vancouver, ISO itp.

45

Ivanov, Alexander A. "Development, validation and clinical application of finite element human pelvis model". Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=mco1213734675.

Pełny tekst źródła

Streszczenie:

Thesis (M.S.)--University of Toledo, 2008.
"In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. Bibliography: p. 96-109.

Style APA, Harvard, Vancouver, ISO itp.

46

Jessee, J. Patrick. "A coupled thermal-magnetic finite element model for high frequency transformers". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-12172008-063409/.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

47

Paul, Van Emburg David. "Finite element model of a capacitive transducer for measuring surface motion". Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17553.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

48

Carnell, Peter Hamilton. "A finite element model for estimating mechanical properties of the cornea". Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17946.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

49

Yassi, Hocine. "Finite element model for the two dimensional spatial spread of rabies". Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318087.

Pełny tekst źródła

Style APA, Harvard, Vancouver, ISO itp.

50

Van, Dyke Gregory G. "Parametric study of a finite element model of the sidewinder missile". Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/26686.

Pełny tekst źródła

Streszczenie:

The long range Maritime Patrol mission has evolved and expanded such that the U. S. Navy's maritime patrol aircraft (P-3C Orion) has become an attractive platform from which to employ a wide variety of air launched weapons. Specifically the need for a stand alone air-to-air defensive capability was identified. In 1989 the Naval Air Test Center at Patuxent River, Maryland began investigations for this through the P-3C/AIM-9 integration program. Naval Postgraduate School responded to this with the construction of a ground vibration test stand and the conduction of a preliminary vibrational characterization of the AIM-9 missile. From these tests a two degree of freedom lumped mass model was developed along with the determination of the primary and secondary missile resonate modes in pitch. In addition, a mathematical model of the AIM-9 missile was developed using finite element techniques. This model was used to analytically determine the modal parameters of the missile and set up a modal parameters of the missile and set up a model test system to experimentally verify the model parameters in view of natural frequencies, mode shapes and transient response

Style APA, Harvard, Vancouver, ISO itp.

Rozprawy doktorskie na temat „Finite element - Humanbody model”

Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych