Дисертації: "Mechanics of rigid bodies"

1

Fandrich, Martin Edward. "Impact mechanics of rigid and compliant bodies." Thesis, University of Cambridge, 1997. https://www.repository.cam.ac.uk/handle/1810/275244.

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2

Tarama, Daisuke. "Classical and Quantum Mechanics, and Complex Algebraic Geometry of Free Rigid Bodies." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157481.

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3

Daily, David J. "Fluid-Structure Interactions with Flexible and Rigid Bodies." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3791.

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Fluid structure interactions occur to some extent in nearly every type of fluid flow. Understanding how structures interact with fluids and visa-versa is of vital importance in many engineering applications. The purpose of this research is to explore how fluids interact with flexible and rigid structures. A computational model was used to model the fluid structure interactions of vibrating synthetic vocal folds. The model simulated the coupling of the fluid and solid domains using a fluid-structure interface boundary condition. The fluid domain used a slightly compressible flow solver to allow for the possibility of acoustic coupling with the subglottal geometry and vibration of the vocal fold model. As the subglottis lengthened, the frequency of vibration decreased until a new acoustic mode could form in the subglottis. Synthetic aperture particle image velocimetry (SAPIV) is a three-dimensional particle tracking technique. SAPIV was used to image the jet of air that emerges from vibrating human vocal folds (glottal jet) during phonation. The three-dimensional reconstruction of the glottal jet found faint evidence of flow characteristics seen in previous research, such as axis-switching, but did not have sufficient resolution to detect small features. SAPIV was further applied to reconstruct the smaller flow characteristics of the glottal jet of vibrating synthetic vocal folds. Two- and four-layer synthetic vocal fold models were used to determine how the glottal jet from the synthetic models compared to the glottal jet from excised human vocal folds. The two- and four-layer models clearly exhibited axis-switching which has been seen in other 3D analyses of the glottal jet. Cavitation in a quiescent fluid can break a rigid structure such as a glass bottle. A new cavitation number was derived to include acceleration and pressure head at cavitation onset. A cavitation stick was used to validate the cavitation number by filling it with different depths and hitting the stick to cause fluid cavitation. Acceleration was measured using an accelerometer and cavitation bubbles were detected using a high-speed camera. Cavitation in an accelerating fluid occurred at a cavitation number of 1.

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4

Tian, Xijin. "Modeling of planar elastically coupled rigid bodies: Geometric algebra methods and applications." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280214.

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This study presents two new, generic methods to modeling planar elastically coupled rigid body systems using Geometric Algebra. The two methods are twist-based potential energy function method and twistor-based potential energy function method. In this research, the rigid body motion in the plane is modeled as a twist or twistor motion in which the rotational motion and translational motion happen simultaneously. The twist is denoted as a bivector using Geometric Algebra which facilitates the notation and computation. A twistor is defined in an intermediate frame half way between two displacement frames. The twistor parameters intuitively represent the relative displacement between two frames. Both twist-based and twistor-based potential energy functions are shown to be frame-independent and body-independent. The kinematics is studied using twist and twistor parameters. The constitutive equations are derived in which the wrench exerted by a pair of elastic bodies is computable given twist or twistor displacements. To analyze large displacements, this study also provides two higher order polynomial potential energy functions of twist parameters and twistor parameters. The polynomial potential energy functions are also shown to be frame-independent and body-independent. They are generally applicable to analyze large displacements of elastically coupled rigid body systems. Several case studies are provided in this research to demonstrate the utility of the presented modeling methods. A micropositioning stage device is modeled as a flexural mechanism with 6 rigid bodies and 7 flexural joints. Simulation is performed using Scilab software. The simulation results show good agreement with actual experimental data. The methods are also applied to simulate the displacement of flexural four-bar linkages with various geometry and various flexural hinges. This case study shows that the presented methods in this research are generic and case-independent. In another case study, the higher order polynomial function method is applied to fit some randomly generated data which demonstrates the generality of the method and the applicability of the method in cases when only experimental data is available without knowing the geometry parameters of a mechanism. The case study of modeling electrostatic potential energy between liquid water molecules using polynomial function of twistor shows the potential utility of the method in the analysis of large displacement. The methods presented in this research have been shown to be generic, easily applicable, and easily computable.

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5

Reis, António Manuel Malvas. "Estudo piloto da variabilidade do padrão de execução técnica no decurso da prova de 400 metros livres em natação." Master's thesis, Instituições portuguesas -- UP-Universidade do Porto -- -Faculdade de Ciências do Desporto e de Educação Física, 2002. http://dited.bn.pt:80/29580.

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6

Couceiro, Maria Teresa Fernandes. "Análise biomecânica do flick-flick na trave olímpica." Master's thesis, Instituições portuguesas -- UP-Universidade do Porto -- -Faculdade de Ciências do Desporto e de Educação Física, 2000. http://dited.bn.pt:80/29214.

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7

Moreira, Pelágio. "Análise das interacções de uma técnica base em trampolis com quatro técnicas complexas." Master's thesis, Instituições portuguesas -- UTL-Universidade Técnica de Lisboa -- -Faculdade de Motricidade Humana, 2000. http://dited.bn.pt:80/29332.

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8

Graziano, Alberto da Conceição Liberto. "Caracterização biomecânica do remate em suspensão com corrida no andebol-uma abordagem cinemática, dinâmica e electromiográfica." Phd thesis, Instituições portuguesas -- UP-Universidade do Porto -- -Faculdade de Ciências do Desporto e de Educação Física, 2002. http://dited.bn.pt:80/29621.

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9

Cruz, Maria João Bezerra. "Estudo biomecânico de três técnicas de partida para provas ventrais de natação-abordagem cinemática e dinâmica." Master's thesis, Instituições portuguesas -- UP-Universidade do Porto -- -Faculdade de Ciências do Desporto e de Educação Física, 2000. http://dited.bn.pt:80/29180.

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10

Vaillant, Timothée. "Rotation à long terme des corps célestes et application à Cérès et Vesta." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEO005/document.

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Le sujet de cette thèse est l'étude de la rotation à long terme des corps célestes.La première partie est consacrée à l’étude de la rotation à long terme de Cérès et Vesta, les deux corps les plus massifs de la ceinture principale d’astéroïdes. Ils sont l’objet d’étude de la sonde spatiale Dawn, qui a permis de déterminer précisément les caractéristiques physiques et de rotation nécessaires au calcul de leurs rotations. La distribution de glace sous et à la surface de Cérès dépend du mouvement de son axe de rotation par le biais de l’obliquité, inclinaison de l’équateur sur l’orbite. Les rotations de Cérès et Vesta étant rapides, l’évolution à long terme des axes de rotation de Cérès et Vesta a été obtenue à l'aide d'une intégration symplectique des équations de la rotation, où une moyenne a été réalisée sur la rotation propre rapide. La stabilité des axes de rotation de Cérès et Vesta a été étudiée en fonction des paramètres de la rotation avec un modèle séculaire semi-analytique, qui a permis de montrer que les axes de rotation ne présentaient pas de caractère chaotique.La seconde partie concerne le développement d'intégrateurs symplectiques dédiés au corps solide. L'intégration de la rotation propre d'un corps solide nécessite d’intégrer les équations issues du hamiltonien du corps solide libre. Ce hamiltonien est certes intégrable et présente une solution explicite nécessitant l’usage des fonctions elliptiques de Jacobi, cependant le coût numérique de ces fonctions est élevé. Lorsque le hamiltonien du corps solide libre est couplé avec une énergie potentielle, l’orientation du corps doit être calculée à chaque pas d’intégration, ce qui augmente le temps de calcul. Des intégrateurs symplectiques ont ainsi été précédemment proposés pour le corps solide libre. Dans ce travail, des intégrateurs spécifiques au corps solide ont été développés en utilisant les propriétés de l’algèbre de Lie du moment cinétique
This thesis concerns the long-term rotation of celestial bodies.The first part is a study of the long-term rotation of Ceres and Vesta, the two heaviest bodies of the main asteroid belt. The spacescraft Dawn studied these two objects and determined the physical and rotational characteristics, which are necessary for the computation of their rotations. The ice distribution under and on the surface of Ceres depends on the evolution of the obliquity, which is the inclination of the equatorial plane on the orbital plane. As the rotations of Ceres and Vesta are fast, the long-term evolution of the spin axes of Ceres and Vesta was obtained by realizing a symplectic integration of the equations of the rotation averaged on the fast proper rotation. The stability of the spin axes of Ceres and Vesta was studied with respect to the parameters of the rotation with a secular and semi-analytical model, which allowed to show that the spin axes are not chaotic.The second part concerns the development of symplectic integrators dedicated to the rigid body. The integration of the proper rotation of a rigid body needs to integrate the equations given by the Hamiltonian of the free rigid body. This Hamiltonian is integrable and presents an explicit solution using the Jacobi elliptic functions. However, the numerical cost of these functions is high. When the Hamiltonian of the free rigid body is coupled to a potential energy, the orientation of the body is needed at each step, which increases the computation time. Symplectic integrators were then previously proposed for the free rigid body. In this work, symplectic integrators dedicated to the rigid body were developed using the properties of the Lie algebra of the angular momentum

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11

He, Wendy. "Computer animation of particles and rigid bodies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0005/MQ32399.pdf.

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12

Weinstein, Rachel Lara. "Simulation and control of articulated rigid bodies /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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13

He, Wen (Wendy) Carleton University Dissertation Engineering Systems and Computer. "Computer animation of particles and rigid bodies." Ottawa, 1997.

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14

Long, Jie. "Animating Non-Rigid Bodies Using Motion Capture." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3396.

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Simulating the motion of a non-rigid body under external forces is a difficult problem because of the complexity and flexibility of the non-rigid geometry and its associated dynamics. Physically based animation of objects moving in the wind is computationally expensive, so simulation-based approaches oversimplify the model by ignoring important effects, such as tree's sheltering. Motion capture records actual responses of a non-rigid body to external forces and helps solve these problems. Mainly focusing on natural trees and ropes as instances of non-rigid bodies, we present a new approach to building motion for objects in wind using incomplete motion capture data from non-rigid bodies. The incomplete motion capture data are automatically labeled by a cluster-based algorithm while noises are removed. For places with no motion capture data, we estimate forces and motion by interpolating the motion capture data according to the object's characteristics. We discuss a physically or statistically based approach to animate the whole non-rigid object. Basing our work on the collected motion capture data and the estimated motions, we can produce visually plausible and scalable animations of non-rigid objects under external forces at interactive frame rates.

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15

Lewin, Christopher. "Constraint based simulation of soft and rigid bodies." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687373.

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This dissertation presents a number of related works in real-time physical animation, centered around the theme of constraint-based simulation. Methods used for real-time simulation of deformable bodies tend to differ quite substantially from those used in offline simulation; we discuss the reasons for this and propose a new position-based finite element method that attempts to produce more realistic simulations with these methods. We also consider and adapt other methods to make them more suitable for game physics simulation. Finally, we adapt some concepts from deformable body simulation to define a deformable rod constraint between rigid bodies that allows us to represent the kinematics of the human spine using fewer degrees of freedom than required with a strictly joint-based model.

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16

FERREIRA, EDSON LUIZ CATALDO. "MODELING AND SIMULATION OF PLANE COLLISIONS BETWEEN RIGID BODIES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2083@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
Em geral, o movimento de corpos se dá em ambiente com barreiras podendo ocorrer colisões. Para que seja possível fazer previsões da dinâmica é necessário saber o que acontece quando um corpo colide. O problema é portanto: conhecida a dinâmica do corpo pré-colisão e as propriedades dos corpos que colidem, prever a dinâmica pós-colisão. Os primeiros trabalhos publicados sobre o assunto datam de 1668 e, até 1984,os modelos existentes pareciam satisfatórios. Porém a aplicação de um desses modelos a um problema simples apresentou geração de energia. Desde então, um grande número de trabalhos tem aparecido na literatura. A tese trata de problema de colisões planas, discute criticamente os modelos da literatura comparando-os através de uma generalização por nós desenvolvida e propõe um novo modelo que engloba alguns dos modelos da literatura. Mostramos os principais problemas de alguns dos modelos e discutimos questões de existência e unicidade. Simulações feitas num programa por nós desenvolvido são apresentadas e ajudam a entender a influência dos coeficientes constitutivos. A validação dos resultados é realizada através de resultados experimentais colhidos da literatura.
In general the motion of a body takes place in a confined environment and collision of the body with the containing wall is possible. To predict the dynamics of a body in this conditions one must know what happens in a collision. The problem is then: known the pre-collision dynamics of the body and the properties of the body and the wall one want to predict the post-collision dynamics. This problem is quite old and it appeared in the literature in 1968. Up to 1984 it seemed that Newton model was enough to solve the problem. But it was found that this was not the case and a renewed interest in the problem appeared. This thesis treats the problem of plan collisions of rigid bodies and tries to classify the differents models and to compare them. A new model is presented and old results are shown in a new framework.

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17

Vilela, João Vítor Cavalcanti. "Attitude control of rigid bodies with time-delayed measurements." reponame:Repositório Institucional da UnB, 2016. http://repositorio.unb.br/handle/10482/23347.

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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2016.
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Desenvolver condições de estabilidade e projeto de controladores para controle de atitude de corpos rígidos sujeitos a atrasos no tempo é o objetivo desta dissertação. O modelo utilizado, escrito na forma de equação diferencial atrasada, advém das equações cinemática e dinâmica do corpo rígido modificadas considerando atrasos temporais. Estes atrasos podem representar latências dos sensores e atuadores, além de tempo de processamento de dados (e.g., cômputo dos sinais de controle) e de transmissão de dados quando os elementos do sistema de controle estão conectados por redes comunicação. Em particular, são supostos atrasos desconhecidos e variantes no tempo, o que lhes confere generalidade maior do que os casos abordados até então na literatura, onde os poucos trabalhos que abordaram o problema aprensentam resultados dependentes do valor exato do atraso ou o assumem constante, o que na prática dificilmente é verificado. As condições obtidas, escritas na forma de teoremas, são baseadas em sua maioria na teoria de Lyapunov-Krasovskii. Outro aspecto que diferencia este trabalho em relação aos demais é que os teoremas são formulados como desigualdades matriciais lineares (LMIs, em inglês). A formulação por LMIs é vantajosa não só pelas excelentes propriedades computacionais das LMIs (resolução em tempo polinomial), mas também porque as condições são escritas com variáveis, reduzindo o conservadorismo dos resultados e permitindo a automação do processo de verificação de estabilidade e projeto de controladores, o que também é uma contribuição desta dissertação. Além disso, os controladores possuem performance garantida segundo o critério H∞ , isto é, além de estabilidade, este tipo de controlador tem um nível mínimo de atenuação de perturbações assegurado.
Developing stability and controller design conditions for rigid body attitude control subjected to time delays is the goal of this dissertation. The rigid body model, written in form of functional differential equation, stems from the kinematic and dynamic rigid body equations, modified to take time delays into account. Such time delays may represent sensor and actuator latency, processing time (e.g., computing control signals) and transmission lags when the control system elements are connected by communication networks. In particular, time delays are considered unknown and time-varying, which makes them generalizations of previous results in literature, where the scarce works to tackle the problem present results dependent on the exact time delay value, which is hardly verified in practice. The proposed conditions, written as theorems, are mostly based on Lyapunov-Krasovskii theory. Another aspect that sets this work apart is that theorems are formulated as linear matrix inequalities (LMIs). LMI formulation is advantageous not only for its excellent computational properties (polynomial time solving), but also for the conditions are written with variables, which reduces results' conservatism e enables automating stability verification and controller design, which is a contribution of this work as well. In addition, controllers attain guaranteed performance according to H∞ criterion, that is, besides stability, this kind of controller presents a known minimum level of perturbation attenuation.

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18

Cordier, Michelle Renee. "On Bodies Whose Shadows Are Related Via Rigid Motions." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1429547907.

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19

Umakanthan, Saravanan. "Mechanics of prestressed and inhomogeneous bodies." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4241.

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In finite elasticity, while developing representation for stress, it is customary to require the reference configuration to be stress free. This study relaxes this requirement and develops representations for stress from a stressed reference configuration. Using the fact that the value of Cauchy stress in the current configuration is independent of the choice of the reference configuration, even though the formula used to compute it depends on the choice of the reference configuration, the sought representation is obtained. It is then assumed that there exists a piecewise smooth mapping between a configuration with prestresses and a configuration that is stress free, and the representation obtained above is used to study the mechanical response of prestressed bodies. The prestress fields are obtained by directly integrating the balance of linear momentum along with the traction free boundary condition. Then, different classes of boundary value problems for the type of inhomogeneous and prestressed bodies of interest are formulated and studied. For the cases studied, it is found that even the global measures like axial-load required to engender a given stretch ratio for a prestressed body vary from the homogeneous stress free bodies, though not significantly. The local measures - stress and deformation - in a prestressed body differ considerably from their homogeneous stress free counterparts. The above gained knowledge is applied to understand the mechanics of circumflex arteries obtained from normotensive and hypertensive micro-mini pigs. It is found that the deformation of these arteries when subjected to inflation and axial extension is not of the form r = r(R), ÃÂµ = ÃÂ£, z = Z. Comparison is also made between the response of an artery at various levels of smooth muscle activation and stretch ratio as well as normotensive and hypertensive specimens, using statistical methods.

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20

Rutstam, Nils. "Study of equations for Tippe Top and related rigid bodies." Licentiate thesis, Linköpings universitet, Tillämpad matematik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-60835.

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The Tippe Top consist of a small truncated sphere with a peg as a handle. When it is spun fast enough on its spherical part it starts to turn upside down and ends up spinning on the peg. This counterintuitive behaviour, called inversion, is a curious feature of this dynamical system that has been studied for some time, but obtaining a complete description of the dynamics of inversion has proved to be a difficult problem. The existing results are either numerical simulations of the equations of motion or asymptotic analysis that shows that the inverted position is the only attractive and stable position under certain conditions. This thesis will present methods to analyze the equations of motion of the Tippe Top, which we study in three equivalent forms that each helps us to understand different aspects of the inversion phenomenon. Our study of the Tippe Top also focuses on the role of the underlying assumptions in the standard model for the external force, and what consequences these assumptions have, in particular for the asymptotic cases. We define two dynamical systems as an aid to understand the dynamics of the Tippe Top, the gliding heavy symmetric top and the gliding eccentric cylinder. The gliding heavy symmetric top is a natural non-integrable generalization of the well-known heavy symmetric top. Equations of motion and asymptotics for this system are derived, but we also show that equations for the gliding heavy symmetric top can be obtained as a limit of the equations for the Tippe Top. The equations for the gliding eccentric cylinder can be interpreted as a special case of the equations for the Tippe Top, and since it is a simpler system, properties of the Tippe Top equations are easier to study. In particular, asymptotic analysis of the gliding eccentric cylinder reveals that the standard model seems to have inconsistencies that need to be addressed.

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21

Neethling, Rufus Stephanus. "Numerical simulation of systems of rigid bodies / Rufus Stephanus Neethling." Thesis, North-West University, 2004. http://hdl.handle.net/10394/596.

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This study investigated the various techniques available for rigid body system simulation, thus providing a thorough overview of the latest relevant literature. N became apparent that no engineering level accurate impulsive approaches for rigid body system simulation with concurrent contacts were in use or even existed up to now. A general formulation and solution technique for multiple concurrent contact problems were developed and tested on simple systems. Advantages of the formulation used are that the minimum of material properties, i.e. density, normal and tangential restitution coefficients and static and dynamic friction factors - all measurable, need to be specified and the results should be physically correct to a very high precision. Results obtained were encouraging and demonstrated that the original binary collision model available thus far could at least be extended to a heptenary simultaneous collision model.
Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2005.

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22

Moreau, Filip. "Physics-Based, Real-Time Simulation of Fluid-Immersed Rigid Bodies." Thesis, Malmö universitet, Fakulteten för teknik och samhälle (TS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-43343.

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Objects interacting with fluid are of high interest to visually present in three-dimensional applications, such as computer games and virtual environments. For presenting the interactions with high correctness, dynamic rigid body simulation may be used. This paper presents methods for efficient, physics-based real-time simulation of fluid-immersed rigid bodies, where the correctness of the simulation is maintained. Simulated forces include gravity, buoyancy, thrust, drag, and lift. To have the simulation run efficiently in real-time, discretization of the simulated rigid body is made by applying mentioned forces to a user-defined number of particles, sampled pseudo-randomly within the rigid body.

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23

Benson, M. "Flow past bluff bodies." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382725.

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24

Schlanbusch, Rune. "Control of rigid bodies : with applications to leader-follower spacecraft formations." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16464.

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25

Duff, Damien Jade. "Visual motion estimation and tracking of rigid bodies by physical simulation." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2927/.

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This thesis applies knowledge of the physical dynamics of objects to estimating object motion from vision when estimation from vision alone fails. It differentiates itself from existing physics-based vision by building in robustness to situations where existing visual estimation tends to fail: fast motion, blur, glare, distractors, and partial or full occlusion. A real-time physics simulator is incorporated into a stochastic framework by adding several different models of how noise is injected into the dynamics. Several different algorithms are proposed and experimentally validated on two problems: motion estimation and object tracking. The performance of visual motion estimation from colour histograms of a ball moving in two dimensions is improved considerably when a physics simulator is integrated into a MAP procedure involving non-linear optimisation and RANSAC-like methods. Process noise or initial condition noise in conjunction with a physics-based dynamics results in improved robustness on hard visual problems. A particle filter applied to the task of full 6D visual tracking of the pose an object being pushed by a robot in a table-top environment is improved on difficult visual problems by incorporating a simulator as a dynamics model and injecting noise as forces into the simulator.

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26

Gissler, Christoph [Verfasser], and Matthias [Akademischer Betreuer] Teschner. "Beyond fluids: SPH simulation of rigid bodies, snow and air interactions." Freiburg : Universität, 2021. http://d-nb.info/1238016057/34.

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27

Wichers, Schreur Bernardus Gerardus Joseph. "The motion of buoyant bodies." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358851.

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28

Armstrong, Brian Jeffrey. "Unsteady flow over bluff bodies." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/11409.

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29

Carlson, Mark Thomas. "Rigid, Melting, and Flowing Fluid." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4807.

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This work focuses on the simulation of fluids as they transition between a solid and a liquid state, and as they interact with rigid bodies in a realistic fashion. There is an underlying theme to my work that I did not recognize until I examined my body of research as a whole. The equations of motion that are generally considered appropriate only for liquids or gas can also be used to model solids. Without adding extra constraints, one can model a solid simply as a fluid with a high viscosity. Admittedly, this representation will only get you so far, but this simple representation can create some very nice animations of objects that start as solids, and then melt into liquid over time. Another way to represent solids with the fluid equations is to add extra constraints to the equations. I use this representation in the parts of this work that focus on the two-way coupling of liquids with rigid bodies. The coupling affects both how the liquid moves the rigid bodies, and how the rigid bodies in turn affect the motion of the fluid. There are three components that are needed to allow solids and fluids to interact: a rigid body solver, a fluid solver, and a mechanism for the coupling of the two solvers. The fluid solver used in this work was presented in [8]. This Melting and Flowing solver is a fast and stable system for animating materials that melt, flow, and solidify. Examples of realworld materials that exhibit these phenomena include melting candles, lava flow, the hardening of cement, icicle formation, and limestone deposition. Key to this fluid solver is the idea that we can plausibly simulate such phenomena by simply varying the viscosity inside a standard fluid solver, treating solid and nearly-solid materials as very high viscosity fluids. The computational method modifies the Marker-And-Cell algorithm [99] in order to rapidly simulate fluids with variable and arbitrarily high viscosity. The modifications allow the viscosity of the material to change in space and time according to variation in temperature, water content, or any other spatial variable. This in turn allows different locations in the same continuous material to exhibit states ranging from the absolute rigidity or slight bending of hardened wax to the splashing and sloshing of water. The coupling that ties together the rigid body and fluid solvers was presented in [7], and is known as the Rigid Fluid method. It is a technique for animating the interplay between rigid bodies and viscous incompressible fluid with free surfaces. Distributed Lagrange multipliers are used to ensure two-way coupling that generates realistic motion for both the solid objects and the fluid as they interact with one another. The rigid fluid method is so named because the simulator treats the rigid objects as if they were made of fluid. The rigidity of such an object is maintained by identifying the region of the velocity field that is inside the object and constraining those velocities to be rigid body motion. The rigid fluid method is straightforward to implement, incurs very little computational overhead, and can be added as a bridge between current fluid simulators and rigid body solvers. Many solid objects of different densities (e.g., wood or lead) can be combined in the same animation. The rigid body solver used in this work is the impulse based solver, with shock propagation introduced by Guendelman et al. in [36]. The rigid body solver allows for collisions ranging from completely elastic, where an object can bounce around forever without loss of energy, to completely inelastic where all energy is spent in the collision. Static and dynamic frictional forces are also incorporated. The details of this rigid body solver will not be discussed, but the small changes needed to couple this solver to interact with fluid will be. When simulating fluids, the fluid-air interface (free surface) is an important part of the simulation. In [8], the free surface is modelled by a set of marker particles, and after running a simulation we create detailed polygonal models of the fluid by splatting particles into a volumetric grid and then render these models using ray tracing with sub-surface scattering. In [7], I model the free surface with a particle level set technique [14]. The surface is then rendered by first extracting a triangulated surface from the level set and then ray tracing that surface with the Persistence of Vision Raytracer (http://povray.org).

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30

Snively, Eric. "Rigid Body Mechanics of Prey Capture in Large Carnivorous Dinosaurs." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1322668677.

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31

Yue, Zhongqi Carleton University Dissertation Engineering Civil. "Mechanics of rigid disc inclusions in fluid saturated poroelastic media." Ottawa, 1992.

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32

Rokseth, Børge. "A Bond Graph Approach for Modelling Systems of Rigid Bodies in Spatial Motion." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25579.

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The research presented in this thesis seeks to improve the current state and technique for dynamic modelling of systems of rigid bodies in spatial motion. The research have been focused around modelling of underwater vehicles and robotic manipulators. Dynamic modelling of such systems are of growing importance as the demand for precise motion control with an increasing degree of autonomy continue to grow. This thesis presents a modelling framework which enables model developers to create a basic bond graph template for a system of rigid bodies in spatial motion. This template can be used as a base for further model development, on which the developer can utilize the modularity virtue of the bond graph by interfacing sub models of various systems. An effective method for developing and implementing such a basic template in bond graph software is presented. Then the virtues of this approach is demonstrated through two case studies. In the first case study a simulator for a seven degrees of freedom manipulator is created, onto which a high fidelity hydraulic actuator system is developed and connected seamlessly. Then a control system, taking input from a joystick is developed for the manipulator. The second case study presents a dynamic model of a remotely operated vehicle equipped with a robotic manipulator. First a basic template for this system is developed, according to the method presented in this thesis. The basic template is then extended by integrating an advanced thruster system and a motion control system to the vehicle. Hydrodynamic added mass and damping is also included to both the manipulator and the vehicle, and the manipulator is equipped with a control system. Finally, an interface to the external world through the manipulator end effector is developed. This external interface is used in order to create a simulation where the vehicle and manipulator system lifts an object, relocates it and places it down at the new location. Simulation results from this is provided.

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33

Hedin, Kajsa. "Design of semi-rigid cables for harsh vibration environment." Thesis, KTH, Hållfasthetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284522.

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This thesis investigates semi-rigid cables exposed to a harsh vibration environment. Thethesis includes the creation of a simulation model of the semi-rigid cables as well asdeveloping a set-up and performing a experimental vibration test. It was shown that thecables could be modeled as a isotropic material with a fitted elastic modulus of 55 GPaand give accurate results in comparison with the experimental vibration test. However itis important that the boundary conditions of the cable are applied correctly. Regardingthe lifetime of the cables it was shown that pre-stress, due to a bending moment, inthe cables did not effect the lifetime of the cables. The amplitude moment, due to theoscillation in the cable from the random vibration, did however effect the lifetime of thecables. With data from the simulations and the vibration test an equation describingrelation between the amplitude moment and the number of cycles the cable was exposedto could be formulated.
Den här master rapporten undersöker semi-rigida kablar som utsätts för en hård vibrationsmiljö. Rapporten inkluderar en simulations modellering av de semi-rigida kablarna samt utvecklandet av en fixturmodell som sedan undersökts i ett experimentellt vibrationstest. Det visades att kablarna kunde modelleras som ett isotropiskt material med en elastisk modul på 55 GPa och ge korrekta resultat i jämförelse med det experimentella vibrationstestet. Det var viktigt att analysera randvillkoren så att de applicerades rätt vid modelleringen. Vad gäller livslängden på kablarna visades det att förspänning, på grund av böjmoment, i kablarna inte påverkade livslängden. Amplitudmomentet, på grund av oscillationen som skapas i kablarna vid vibrering, påverkade livslängden och en ekvation som beskriver förhållandet mellan amplitudmomentet och antal cykler som kabeln utsattes för kundes ta fram.

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34

Gomez, Miguel J. "Optimization-based analysis of rigid mechanical systems with unilateral contact and kinetic friction /." Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/6793.

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35

Cornett, Andrew Malcolm. "Short-crested wave forces on a rigid segmented vertical cylinder." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26688.

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This thesis investigates water particle kinematics and the wave forces exerted on a slender rigid vertical cylinder in regular bidirectional wave fields. The instrumented portion of this cylinder is partitioned into nine independent segments enabling measurement of the vertical profile of hydrodynamic loading both in-line and transverse to the direction of wave propagation. Experiments conducted at the Hydraulics Laboratory of the National Research Council in Ottawa are described and some results are compared with the predictions of a wave force model based on the Morison equation and linear fluid kinematics. The influence of the crossing angle between the two wave components on the forces experienced by the column is determined. These experiments consider short-crested wave behavior in intermediate and deep water resulting from the interaction of two identical regular wave trains crossing at angles of 30, 60 and 90 degrees. The limit corresponding to unidirectional monochromatic waves is also investigated to provide a reference condition for comparison with the short-crested results. Conditions at the location of maximum short-crested wave height are of primary interest, however, forces at locations between the anti-node and node of the flow are also examined. In all, water surface elevations, flow velocities, and wave forces were measured in 24 short-crested and 8 different long-crested wave conditions spanning the range of Keulegan-Carpenter number between 4 and 24. The results of this study confirm the findings of previous researchers that short -crested waves with a certain period travel faster and rise higher before breaking than do their long-crested counterparts, but that in-line wave forces are not necessarily increased. Lift force maxima equal to half the maximum in-line force were measured; these forces can contribute significantly to the magnitude and direction of the total force resultant.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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36

Pitt-Francis, Joseph M. "Dynamics of solid bodies in a rotating viscous fluid." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386716.

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37

Hahn, James Kwangjune. "The use of simulation techniques for motion control of rigid bodies in computer graphics /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487671640056213.

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38

Brunt, Susan Mary. "Scatterring of water waves by rigid bodies in three dimensions, using the null-field method." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237064.

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39

Mitchell, Jason W. "A Simplified Variation of Parameters Solution for the Motion of an Arbitrarily Torqued Mass Asymmetric Rigid Body." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin962392147.

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40

Ghadiri, Dehkordi Behzad. "Numerical simulation of the viscous flow around bluff bodies via the random Vortex method." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41598.

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The viscous, incompressible and laminar flow around bluff bodies is analysed via a random vortex method using a hybrid (Eulerian-Lagrangian) scheme. The Navier-Stokes equations, written in the form of vorticity equations, are split into nonlinear convection and linear diffusion parts according to a fractional step method. Vorticity is modelled by discrete point vortices. Vortices are created on the surface to satisfy the zero tangential velocity boundary condition. Random walks are applied to the vortices to simulate the diffusion equation. Vortices are then convected in an inviscid calculation in the Lagrangian scheme to simulate the convection equation. The velocity of each vortex is calculated using the Clould-in-Cell method.
The random vortex method is developed to simulate the flow around a circular cylinder with a splitter plate. A conformal transformation is used to map the cylinder with a splitter plate to a unit circular cylinder. The force coefficients and Strouhal number are presented for various lengths of the splitter plate and are in good agreement with experiments.
The random vortex method has also been developed for the flow around a circular cylinder vibrating transverse to the flow in a channel. The results are presented for various values of Reynolds number, forcing frequency and vibration amplitudes. The effect of blockage on the drag coefficient is presented. The drag coefficient and vortex shedding frequency are shown to compare favourably with experimental results. The flow around a vibrating cylinder with a splitter plate is also simulated. The results are presented for various values of forcing frequency and lengths of the splitter plate.
The flow around multiple stationary cylinders is also simulated. Also, results are presented for the flow around two cylinders, one of which is forced to oscillate in a transverse direction. The numerical results of Strouhal number are in reasonable agreement with experiments.

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41

Beckham, Jon Regan. "Analysis of mathematical models of electrostatically deformed elastic bodies." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 169 p, 2008. http://proquest.umi.com/pqdweb?did=1475178561&sid=27&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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42

Erozkan, Deniz. "Finite Strip With Rigid Ends And Edge Notches." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610880/index.pdf.

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This study considers a symmetrical finite strip with a length of 2L and a width of 2h containing two collinear edge cracks located at the center of the strip. Each edge crack has a width h&
#8211
a. Two ends of the finite strip are bonded to two rigid plates through which uniformly distributed axial tensile loads of intensity p0 are applied. The finite strip is assumed to be made of a linearly elastic and isotropic material. For the solution of the finite strip problem, an infinite strip of width 2h containing two internal cracks of width b&
#8211
a at y=0 and two rigid inclusions of width 2c at y=±
L is considered. When the width of rigid inclusions approach the width of the strip, the portion of the infinite strip between the inclusions becomes identical with the finite strip problem. When the outer edges of the internal cracks approach the edge of the strip, they become edge cracks (notches). Governing equations are solved by using Fourier transform technique and these equations are reduced to a system of three singular integral equations. By using Gauss-Lobatto and Gauss-Jacobi integration formulas, these three singular integral equations are converted to a system of linear algebraic equations which is solved numerically.

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43

Johannesson, Roger. "Simulering av mjuka kroppar för spel." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7683.

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I dagens spelindustri baseras nästan samtliga 3D-spel på fysiksimuleringar med stela kroppar (rigid bodies). Examensarbetet undersöker vilka alternativa modeller som finns för att simulera mjuka deformerbara objekt, deformerbara i det avseendet att de kan ändra form och inte nödvändigtvis att de kan gå sönder i flera bitar. Rapporten inleds med en undersökande del som tar upp några existerande metoder för att hantera dynamiken inom ett mjukt objekt för att sedan beskriva en metod i detalj som dessutom implementeras i ett kodbibliotek. Ett deformerbart objekt är inte så spännande om det inte finns något sätt att deformera det på, därför undersöks även hur kollisionshantering kan gå till. Även här har rapporten först en undersökande del för att sedan beskriva en specifik metod i detalj som implementeras i kodbiblioteket. Examensarbetet resulterar i slutändan i en grundläggande interaktiv simuleringsmiljö för mjuka deformerbara objekt i form av ett kodbibliotek.

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44

Lloyd, Wilson Randolph. "Experimental determination of the stress singularity exponent in cracked bodies using photoelasticity." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91050.

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An experimental program is developed to investigate the three dimensional nature of the stress field surrounding the border of semi-elliptical surface flaws, particularly the singularity exponent. Stress freezing photoelasticity is employed to generate experimental data from nearly incompressible, elastic material. The technique of optical fringe multiplication is utilized to collect data from thin, closely spaced photoelastic slices. A new quasi-linear algorithm for data analysis is developed and verified. The algorithm is implemented using the interactive and graphics capabilities of a microcomputer and digitizing tablet, saving time and reducing errors in photoelastic data analysis. By utilizing CRT graphics, the measurement zone producing the most consistent results is delineated. Results obtained from a series of tests on both surface flaws and straight-front cracks bracket analytical values of the singularity exponent at the flaw border-free surface intersection. Suggestions to decrease variance in the results and possibly cause the results for all tests to coalesce to the analytical value(s) at the free surface are presented. An algebraic formula is developed to account for the singularity exponent variation (3-D effect) by adjusting the magnitude of the classical LEFM mode I stress intensity factor, K_I. A discussion of the need to recognize and account for these effects in high-tech materials is also included.
M.S.

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45

Becker, Jan Verfasser], Rudolf [Akademischer Betreuer] Schmitz, and Hans-Jörg [Akademischer Betreuer] [Kull. "Brownian motion of rigid bodies in compressible fluids under nonisothermal conditions / Jan Becker ; Rudolf Schmitz, Hans-Jörg Kull." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1128231662/34.

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46

Donati, Checone E. "A study of the theoretical and implementation aspects of response prediction methods for rigid floating bodies at sea." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371253.

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47

Becker, Jan [Verfasser], Rudolf [Akademischer Betreuer] Schmitz, and Hans-Jörg [Akademischer Betreuer] Kull. "Brownian motion of rigid bodies in compressible fluids under nonisothermal conditions / Jan Becker ; Rudolf Schmitz, Hans-Jörg Kull." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1128231662/34.

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48

McGregor, Peter Stanley. "Modelling the effect of suspended bodies on cavitation bubbles near a rigid boundary using a boundary integral approach." Thesis, Queensland University of Technology, 2003. https://eprints.qut.edu.au/15822/1/Peter_McGregor_Thesis.pdf.

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Cavitation is the spontaneous vaporisation of a liquid to its gaseous state due to the local absolute pressure falling to the liquid's vapour pressure (Douglas, Gasiorek et al. 1995). Cavitation is present in a wide range of mechanical systems ranging from ship screws to journal bearing. Generally, cavitation is unavoidable and may cause considerable damage and efficiency losses to these systems. This thesis considers hydraulic systems specifically, and uses a modified Greens equation to develop a boundary integral method to simulate the effect that suspended solid bodies have on a single cavitation bubble. Because of the limitations of accurately modelling cavitation bubbles beyond touchdown, results are only presented for cases up to touchdown. The aim of the model is to draw insight into the reasons there is a measurable change in cavitation erosion rate with increasing oil-in-water emulsion percentage. This principle was extended to include the effect that ingested particulates may have on cavitation in hydraulic machinery. Two particular situations are modelled; the first consists of stationary rigid particles in varying proximity to a cavitation bubble near a rigid boundary. The second case is similar; however the suspended particle is allowed to move under the influence of the pressure differential caused by the expanding/contracting cavitation bubble. Numerous characteristics of the domain are considered, including domain pressures and fluid field motion, and individual boundary surface characteristics. The conclusion of the thesis is that solid bodies, either stationary or moving, have little effect on the cavity from an energy perspective. Regardless of size or density, all energy transferred from the cavity to the solid body is returned indicating that there is no net change. As this energy is ultimately responsible for the peak pressure experienced by the domain (and hence responsible for eroding the rigid boundary) as the cavity rebounds, it then serves that a cavity with a solid body will rebound at the same pressure as a cavity without a suspended body present. If this is coupled with the observation that the cavity centroid at touchdown is largely unaffected by the presence of a suspension, then it would appear that the bubble near a solid would rebound at a very similar position as a cavity without a solid. Consequently, the damage potential of a cavity is unaffected by a suspension. However, there is one point of contention as the profile of the re-entrant jet of the cavity is altered by the presence of a suspension. As energy is radiated away from the cavity during penetration, it is possible that the shape of the jet may alter the rate that energy is radiated away during penetration. However, this requires further research to be definitive.

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49

Lu, Dongqiang, and 盧東強. "Unsteady free-surface waves generated by bodies in a viscous fluid." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B29750787.

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50

Goldthorpe, Martin Richard. "An elastic-plastic finite element program with applications to cracked bodies." Thesis, University of Sheffield, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315414.

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Дисертації з теми "Mechanics of rigid bodies"

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