Dissertations / Theses on the topic 'Hydrodynamics linear stability analysis'
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Hadley, Kathryn Z. 1955. "Linear stability analysis of nonaxisymmetric instabilities in self-gravitating polytropic disks." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11253.
Full textAn important problem in astrophysics involves understanding the formation of planetary systems. When a star-forming cloud collapses under gravity its rotation causes it to flatten into a disk. Only a small percentage of the matter near the rotation axis falls inward to create the central object, yet our Sun contains over 99% of the matter of our Solar System. We examine how global hydrodynamic instabilities transport angular momentum through the disk causing material to accrete onto the central star. We analyze the stability of polytropic disks in the linear regime. A power law angular velocity of power q is imposed, and the equilibrium disk structure is found through solution of the time-independent hydrodynamic equations via the Hachisu self-consistent field method. The disk is perturbed, and the time-dependent linearized hydrodynamic equations are used to evolve it. If the system is unstable, the characteristic growth rate and frequency of the perturbation are calculated. We consider modes with azimuthal e im[varphi] dependence, where m is an integer and [varphi] is the azimuthal angle. We map trends across a wide parameter space by varying m , q and the ratios of the star-to-disk mass M * /M d and inner-to-outer disk radius r - /r + . We find that low m modes dominate for small r - /r + , increasing to higher r - /r + as M * /M d increases, independent of q . Three main realms of behavior are identified, for M * << M d , M * [approximate] M d and M * >> M d , and analyzed with respect to the I, J and P mode types as discussed in the literature. Analysis shows that for M * << M d , small r - /r + disks are dominated by low m I modes, which give way to high m J modes at high r - /r + . Low m J modes dominate M * [approximate] M d disks for small r - /r + , while higher m I modes dominate for high r - /r + . Behavior diverges with q for M * >> M d systems with high q models approximating M * [approximate] M d characteristics, while low q models exhibit m = 2 I modes dominating where r - /r + < 0.60.
Committee in charge: Raymond Frey, Chairperson; James Imamura, Advisor; Robert Zimmerman, Member; Paul Csonka, Member; Alan Rempel, Outside Member
Tun, Yarzar. "Nonmodal Analysis of Temporal Transverse Shear Instabilities in Shallow Flows." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36886.
Full textBridel-Bertomeu, Thibault. "Investigation of unsteady phenomena in rotor/stator cavities using Large Eddy Simulation." Thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/17867/1/BRIDEL_BERTOMEU.pdf.
Full textBengana, Yacine. "Simulations numériques pour la prédiction de fréquences par champs moyens." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET032.
Full textFluid flows play an important role in many natural phenomena as well as in many industrial applications. In this thesis, we are interested in oscillating flows origins from a Hopf bifurcation.The open shear-driven square cavity has two limit cycles separated by an unsteady quasi-periodic state. We have described this scenario in detail by using direct numerical simulations, linear stability analysis, and Floquet analysis. The Hopf bifurcation in Taylor-Couette flow gives rise to two solutions, spirals (traveling waves) and ribbons (standing waves in the axial direction). We discovered that the ribbons branch is followed by two consecutive heteroclinic cycles connecting two pairs of axisymmetric vortices. We studied in detail these two heteroclinic cycles.The linear stability analysis about the stationary solution is used to compute the threshold of the bifurcations. Another approach is the linearization about the mean field. This approach gives frequencies very close to that of the nonlinear system and shows in most cases a nearly zero growth rate. We have shown that spirals, ribbons, the lid-driven cavity and the flow around a prismatic object verify this property.In the thermosolutal convection, the frequencies obtained by the linearization about the mean field of the standing waves do not match the nonlinear frequencies and the growth rate is far from zero, on the other hand for the traveling waves this property is fully satisfied. We studied the validity of a self-consistent model in the case of the traveling waves. The self-consistent model consists of the mean field governing equation coupled with the linearized Navier-Stokes equation through the most unstable mode and the Reynolds stress term. This model calculates the mean field, the nonlinear frequency, and the amplitude without time integration. The self-consistent model is assumed to be valid for flows that satisfy the property of the mean field. We have shown that in this case, this model predicts the nonlinear frequency only very close to the threshold. We have improved significantly the predictions by considering higher orders in the Reynolds stress term
Zhang, Mengqi. "Linear stability Analysis of Viscoelastic Flows." Thesis, KTH, Mekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95137.
Full textHu, Bin. "Stability analysis of linear thin shells." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7360/.
Full textVALERIO, JULIANA VIANNA. "LINEAR STABILITY ANALYSIS OF VISCOUS AND VISCOELASTIC FLOWS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10021@1.
Full textCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
As informações sobre a sensibilidade da solução de um dado escoamento mediante a perturbações infinitesimais é importante para o seu completo entendimento. A análise de estabilidade de escoamentos pode ser utilizada na otimização de processos industriais. Na indústria de revestimento o controle da estabilidade é fundamental, uma vez que o escoamento na região de aplicação da camada de líquido sobre o substrato, de um modo geral, tem que ser laminar, bidimensional e em regime permanente. O objetive é determinar, dentro do espaço de parâmetros de operação, a região onde o escoamento é estável e conseqüêntemente a camada a ser revestida uniforme. Porém, por ser uma análise complexa, só é usada na indústria em estudos mais apurados. O sistema linear que descreve a estabilidade vai ser discretizado com o método de Galerkin / elementos finitos, dando origem a um problema de autovalor generalizado.Tanto para escoamentos com líquidos newtonianos como para escoamentos com líquidos viscoelásticos, uma das matrizes do problema de autovalor generalizado é singular e alguns autovalores se encontram no infinito. No escoamento com líquidos viscoelásticos parte do espectro é contínuo, aumentando o grau de dificuldade da análise numérica para encontrá-lo. Nesse trabalho, vamos apresentar um método baseado em transformações lineares tirando vantagem das estruturas matriciais e transformando-as em um problema de autovalor clássico com dimens são, pelo menos, três vezes menor que o original. O método elimina os autovalores infinitos do problema com um baixo custo computacional. A estabilidade de um escoamento de Couette unidimensional de líquido newtoniano é analisada como um primeiro exemplo. Depois, o início do estudo da estabilidade em um escoamento de Couette bidimensional e também um escoamento pistonado com o mesmo líquido. Generaliza-se o método para o escoamento de Couette de um líquido viscoelástico, os resultados para o escoamento de um líquido cujo comportamento mecânico é descrito pelo modelo de Maxwell são apresentados e comparados com a solução analítica de Gorodtsov & Leonov, 1967. A relação entre os autovetores do problema transformado e do original é apresentada.
Steady state,two-dimensional flows may become unstable under two and three-dimensional disturbances, if the flow parameters exceed some critical values. In many practical situations, determining the parameters at which the flow becomes unstable is essential. The complete understanding of viscous and viscoelastic flows requires not only the steady state solution of the governing equations, but also its sensitivity to small perturbations. Linear stability analysis leads to a generalized eigenvalue problem, GEVP. Solving the GEVP is challenging, even for Newtonian liquids, because the incompressibility constraint creates singularities that lead to nonphysical eigenvalues at infinity. For viscoelastic flows, the difficulties are even higher because of the continuous spectrum of eigenmodes associated with differential constitutive equations. The complexity and high computational cost of solving the GEVP have probably discouraged the use of linear stability analysis of incompressible flows as a general engineering tool for design and optimization. The Couette flow of UCM liquids has been used as a classical problem to address some of the important issues related to stability analysis of viscoelastic flows. The spectrum consists of two discrete eigenvalues and a continuous segment of eigenvalues with real part equal to -1/We (We is the Weissenberg number). Most of the numerical approximation of the spectrum of viscoelastic Couette flow presented in the literature were obtained using spectral expansions. The eigenvalues close to the continuous part of the spectrum show very slow convergence. In this work, the linear stability of Couette flow of a Newtonian and UCM liquids were studied using finite element method, which makes it easier to extend the analysis to complex flows. A new procedure to eliminate the eigenvalues at infinity from the GEVP that come from differential equations is also proposed. The procedure takes advantage of the structure of the matrices involved and avoids the computational effort of common mapping techniques. With the proposed procedure, the GEVP is transformed into a smaller simple EVP, making the computations more effcient. Reducing the computational memory and time. The relation between the eigenvector from the original problem and the reduced one is also presented.
Flynn, Terrance J. "Linear stability analysis of a solidifying ternary alloy." Fairfax, VA : George Mason University, 2009. http://hdl.handle.net/1920/4594.
Full textVita: p. 164. Thesis director: Daniel Anderson. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Mathematics. Title from PDF t.p. (viewed Oct. 12, 2009). Includes bibliographical references (p. 163). Also issued in print.
Fang, Yuguang. "Stability analysis of linear control systems with uncertain parameters." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057598985.
Full textBeneddine, Samir. "Characterization of unsteady flow behavior by linear stability analysis." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX010/document.
Full textLinear stability theory has been intensively used over the past decades for the characterization of unsteady flow behaviors. While the existing approaches are numerous, none has the ability to address any general flow. Moreover, clear validity conditions for these techniques are often missing, and this raises the question of their general reliability.In this thesis, this question is addressed by first considering the classical stability approach, which focuses on the evolution of small disturbances about a steady solution -- a base flow -- of the Navier-Stokes equations.To this end, the screech phenomenon -- a tonal noise that is sometimes generated by underexpanded jets -- is studied from alinear stability point of view. The results reveal that the nonlinear dynamics of this phenomenon is well-predicted by a linear base flow stability analysis. A confrontation with other similar analyses from the literature shows that such a satisfactory result is not always observed. However, when a self-sustained oscillating flow is driven by an acoustic feedback loop, as it is the case for the screech phenomenon, cavity flows and impinging jets for instance, then the nonlinearities have a weak impact on the frequency selection process, explaining the ability of a linear analysis to characterize the flow, even in the nonlinear regime.Another alternative approach, based on a linearization about the mean flow, is known to be successful in some cases where a base flow analysis fails. This observation from the literature is explained in this thesis by outlining the role of the resolvent operator, arising from a linearization about the mean flow, in the dynamics of a flow. The main finding is that if this operator displays a clear separation of singular values, which relates to the existence of one strong convective instability mechanism, then the Fourier modes areproportional to the first resolvent modes. This result provides mathematical and physical conditions for the use and meaning of several mean flow stability techniques, such as a parabolised stability equations analysis of a mean flow.Moreover, it leads to a predictive model for the frequency spectrum of a flow field at any arbitrary location, from the sole knowledge of the mean flow and the frequency spectrum at one or more points. All these findings are illustrated and validated in the case of a turbulent backward facing step flow. Finally, these results are exploited in an experimental context, for the reconstruction of the unsteady behavior of a transitional round jet, from the sole knowledge of the mean flow and one point-wise measurement. The study shows that, after following a few experimental precautions, detailed in the manuscript, the reconstruction is very accurate and robust
Zhou, Qing. "Combined linear/nonlinear stability analysis of plane and space frames." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07112009-040327/.
Full textAllen, Leanne. "Modelling dolphin hydrodynamics : the numerical analysis and hydrodynamic stability of flow past compliant surfaces." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/844005/.
Full textWirth, Walter M. "Linear modeling of rotorcraft for stability analysis and preliminary design." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA274869.
Full textDouglas, Jamie George Iain. "Linear stability analysis of non ideal tokamak plasma fluid models." Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614645.
Full textHuang, Shiling. "Linear stability analysis of non-reacting and reacting elliptical jets." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164706/.
Full textXiong, Dapeng. "Stability analysis and controller synthesis of linear parameter varying systems /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Full textAtalayer, Senem Hayriye. "Analysis Of Stability And Transition In Flat Plate Compressible Boundary Layers Using Linear Stability Theory." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605366/index.pdf.
Full textAllievi, Alejandro. "Experimental and numerical analysis of a fishing vessel motions and stability in a longitudinal seaway." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26680.
Full textApplied Science, Faculty of
Mechanical Engineering, Department of
Graduate
Burckhart, Andreas. "Different ELM regimes at ASDEX Upgrade and their linear stability analysis." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-164858.
Full textTang, Ying. "Stability analysis and Tikhonov approximation for linear singularly perturbed hyperbolic systems." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT054/document.
Full textSystems modeled by partial differential equations (PDEs) with infinite dimensional dynamics are relevant for a wide range of physical networks. The control and stability analysis of such systems become a challenge area. Singularly perturbed systems, containing multiple time scales, often occur naturally in physical systems due to the presence of small parasitic parameters, typically small time constants, masses, inductances, moments of inertia. Singular perturbation was introduced in control engineering in late $1960$s, its assimilation in control theory has rapidly developed and has become a tool for analysis and design of control systems. Singular perturbation is a way of neglecting the fast transition and considering them in a separate fast time scale. The present thesis is concerned with a class of linear hyperbolic systems with multiple time scales modeled by a small perturbation parameter. Firstly we study a class of singularly perturbed linear hyperbolic systems of conservation laws. Since the system contains two time scales, by setting the perturbation parameter to zero, the two subsystems, namely the reduced subsystem and the boundary-layer subsystem, are formally computed. The stability of the full system implies the stability of both subsystems. However a counterexample is used to illustrate that the stability of the two subsystems is not enough to guarantee the full system's stability. This shows a major difference with what is well known for linear finite dimensional systems. Moreover, under certain conditions, the Tikhonov approximation for such system is achieved by Lyapunov method. Precisely, the solution of the slow dynamics of the full system is approximated by the solution of the reduced subsystem for sufficiently small perturbation parameter. Secondly the Tikhonov theorem is established for singularly perturbed linear hyperbolic systems of balance laws where the transport velocities and source terms are both dependent on the perturbation parameter as well as the boundary conditions. Under the assumptions on the continuity for such terms and under the stability condition, the estimate of the error between the slow dynamics of the full system and the reduced subsystem is the order of the perturbation parameter. Thirdly, we consider singularly perturbed coupled ordinary differential equation ODE-PDE systems. The stability of both subsystems implies that of the full system where the perturbation parameter is introduced into the dynamics of the PDE system. On the other hand, this is not true for system where the perturbation parameter is presented to the ODE. The Tikhonov theorem for such coupled ODE-PDE systems is proved by Lyapunov technique. Finally, the boundary control synthesis is achieved based on singular perturbation method. The reduced subsystem is convergent in finite time. Boundary control design to different applications are used to illustrate the main results of this work
Kalavagunta, Sushma. "Computational algorithms for stability analysis of linear systems with time-delay /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418036.
Full textLi, Rihua. "Analysis for Taylor vortex flow." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/53628.
Full textPh. D.
KOWTA, SRINIVAS. "ROBUST STABILITY ANALYSIS OF SERVO-HYDRAULIC SYSTEM IN PARAMETER SPACE." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1060970575.
Full textHughes, Jonathan L. "Applications of Stability Analysis to Nonlinear Discrete Dynamical Systems Modeling Interactions." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3819.
Full textHaber, Ludwig Christian. "Investigation of Dynamics in Turbulent Swirling Flows Aided by Linear Stability Analysis." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11076.
Full textPh. D.
Du, Baozhu, and 杜宝珠. "Stability analysis and controller synthesis of continous-time linear time-delay systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44765186.
Full textLeimkuhler, Matthew Pancoast. "Linear stability analysis of circular jets : integer, fractional, and multiple mode excitation /." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06082009-170937/.
Full textMuller, Susan Sanette. "The effect of temperature on the linear dimensional stability of elastomers." University of the Western Cape, 2012. http://hdl.handle.net/11394/4624.
Full textSometimes, dental impressions need to be transported to distant laboratories. It has been reported that the temperature in a vehicle can reach up to 66C when the outdoor temperature is 38C. These temperatures may be reached during South African summers. The objective of this in vitro study was to investigate the effect of temperature and time on the dimensional stability of two elastomeric impression materials. Methodology: Specimens consisted of impressions made of an ISO-specified test-block featuring a pattern of grooves. Materials used were polyether (Impregum Penta) and polyvinylsiloxane (Affinis Precious regular body). Using an SLR camera and standardized technique, the specimens were photographed at 2 different temperatures (21°C and 66°C) and 3 time intervals (30min, 8hrs and 14 days). This resulted in a total of 12 groups (n=10) to be compared. Digital images of the impressions were calibrated and measured using digital analyzing software. These distances were used to evaluate the mean % dimensional change (%DC) for each group. VEPAC module of Statistica 10 was used for the statistical analysis. To analyze exactly where the differences lied, a Fisher LSD correction was applied to correct for multiple pair wise comparisons. Results: Comparing polyether with silicone, there was no difference in the mean %DC for specimens kept at 21°C for 8hrs (polyether=0.364; silicone=0.237). Neither was there a difference between polyether and silicone when heated to 66°C, cooled off, and measured after 8hrs (polyether=0.306; silicone=0.297) or after 14 days (polyether=-0.272; silicone=-0.093). For both polyether and silicone, the mean %DC of the groups exposed to 66°C, cooled off and measured after 8hrs (polyether=0.306; silicone=0.297) differed significantly when compared to the group measured after 14 days (polyether=-0.2723; silicone=-0.092) (P<0.0001 and P=0.0029 resp). For both polyether and silicone, the mean %DC of the groups exposed to 66°C, cooled off and measured after 8hrs (polyether=0.306; silicone=0.297) did not differ when compared to the 21°C (polyether=0.364; silicone=0.237). Conclusions: Within limitations of this study, both materials were heat-sensitive. It is recommended that materials return to 21°C before casting. Despite statistical differences, all results were within ISO specifications of maximum 1.5%DC.
Weeks, Mark Alexander. "Plane-layer convection and magnetoconvection." Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248180.
Full textEr, Aynur. "Stability of Linear Difference Systems in Discrete and Fractional Calculus." TopSCHOLAR®, 2017. http://digitalcommons.wku.edu/theses/1946.
Full textMarinósson, Sigurour Freyr. "Stability analysis of nonlinear systems with linear programming a Lyapunov functions based approach /." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=982323697.
Full textZhang, Xiping. "Parameter-Dependent Lyapunov Functions and Stability Analysis of Linear Parameter-Dependent Dynamical Systems." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5270.
Full textSEREBRENICK, GUSTAVO. "STABILITY ANALYSIS OF SLENDER COLUMNS PARTIALLY BURIED IN A NON-LINEAR ELASTIC FOUNDATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6168@1.
Full textO presente trabalho tem por objetivo estudar o comportamento de colunas esbeltas parcialmente enterradas, quando submetidas a um carregamento axial de compressão. A fundação é representada, ora por um modelo linear, o qual considera que a reação exercida pelo solo é proporcional às deflexões da coluna, ora por um modelo não-linear no qual esta relação de proporcionalidade não é mais verificada. Para a modelagem da coluna, é usada a teoria inextensional de barras esbeltas. Inicialmente, mostra-se como são deduzidas as equações diferenciais do problema a partir dos funcionais de energia da coluna. No problema linear, buscam-se obter as cargas críticas e modos críticos da coluna. Neste caso, sua solução analítica é encontrada a partir da resolução do problema de valor de contorno usando-se um programa de álgebra simbólica. Também é obtida uma solução aproximada através do método de Ritz. Um estudo paramétrico detalhado analisa a influência das condições de apoio da coluna e altura e rigidez da fundação na carga e modo críticos. Entretanto, no caso nãolinear, as equações diferenciais são mais complexas, não permitindo a obtenção de uma solução analítica. É utilizado, então, o método de Ritz, no qual as soluções analíticas obtidas para o problema linear (autofunções) são usadas como funções de interpolação. Em seguida, chega-se à uma equação não- linear de equilíbrio, da qual se obtém o caminho pós-crítico da coluna. Os resultados do problema nãolinear são comparados com os obtidos através do método dos elementos finitos.
In this thesis the behavior of slender, partially embedded columns under axial compressive forces is studied. The foundation is either represented by a linear model, which considers that the soil reaction is proportional to the column’s deflections or by a non-linear model in which this proportionality relation is not observed. The inextensional slender beam theory is used to model the column. Initially, the governing differential equations are deduced from the energy functional of the column-foundation system. In the linear problem, the critical loads and corresponding critical modes are looked for. In this case, an analytic solution is obtained by the solution of the associated boundary value problem, using a symbolic algebra software. An approximate solution is also found by Ritz’s method. A parametric study is conducted to study the influence of the column boundary conditions and foundation’s height and stiffness on critical loads and modes. However, in the non-linear case, differential equations are much more complex and an analytical solution is not possible. So, the Ritz’s method is used once again, in which the analytic solutions of the linear problem (eigenfunctions) are used as interpolation functions. After that, a non-linear equilibrium equation is obtained together with the column post-buckling path. These results are compared with the ones obtained using the finite element method.
Keo, Pisey. "Non-linear analysis of steel-concrete hybrid members with application to stability design." Thesis, Rennes, INSA, 2015. http://www.theses.fr/2015ISAR0040/document.
Full textThis thesis aims at developing simulation tools and a design method for hybrid beam-columns subjected to combined axial force, bending and shear. The thesis is divided in four main parts and comprises 6 chapters. In the first part, we develop a new finite element formulation based on the exact stiffness matrix for the linear elastic analysis of hybrid beam-columns in partial interaction taking into account the shear deformability of the encasing component. This element relies on the analytical solution of a set of coupled system of differential equations in which the primary variables are the slips and the shear deformation of the encasing beam. The latter is derived by combining the governing equations (equilibrium, kinematics, constitutive laws) and solved for a specific element with arbitrary boundary conditions and loading. Special care has been taken while dealing with the constants of integration. The second part of the thesis addresses a new finite element formulation for a large displacement analysis of elastic hybrid beam-columns taking into account the slips that occur at each steel-concrete interface. The co-rotational method is adopted in which the movement of the clement is divided into a rigid body motion and a deformable portion in the local co-rotational frame which moves and rotates continuously with the element but does not deform with it. Appropriate selection of local kinematic variables along with corresponding transformation matrices allows transforming the linear finite element developed in Part I into a nonlinear one resulting in an efficient locking-free formulation. In Part 3, we derive a finite element formulation for materially nonlinear analysis of hybrid beam-columns with shear deformable encasing component, in partial interaction and subjected to the combined shear and bending. The fiber model is adopted with condensation of the 3D stress-strain relations which allow to account for confinement in a rigorous manner as well as the effect of the stirrups. Part 4 examines the adequacy of the moment magnification method given in Eurocode 2 and 4 to provide an accura te estimation of the ultimate load of hybrid columns subjected to a combination of axial load and uniaxial bending moment. The developed finite element model with a shear rigid encasing component is used to conduct a parametric study comprising 1140 cases to cover the various possible situations. The predictions of the model are compared against the values given by the simplified methods of Eurocode 2 and Eurocode 4. lt is shown that these simplified methods does not give satisfactorily results. Based on the analysis of larger number of cases (2960 configurations), the moment magnification method has been calibrated for hybrid columns
Fannin, Christopher A. "Linear Modeling and Analysis of Thermoacoustic Instabilities in a Gas Turbine Combustor." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28400.
Full textPh. D.
Clinger, Richard A. "Stability Analysis of Systems of Difference Equations." VCU Scholars Compass, 2007. http://hdl.handle.net/10156/1318.
Full textCivin, Damon. "Stability of charged rotating black holes for linear scalar perturbations." Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/247397.
Full textTilton, Nils G. "A linear stability analysis of the destabilizing effects of wall permeability in channel flows /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99546.
Full textHaapanen, Siina Ilona. "Linear stability analysis and direct numerical simulation of a miscible two-fluid channel flow /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Full textLiljenberg, Scott Alan. "Modeling and Stability Analysis of Thermoacoustic Instabilities in Gas Turbine Combustor Sections." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35469.
Full textMaster of Science
Marinosson, Sigurdur Freyr. "Stability Analysis of Nonlinear Systems with Linear Programming - Stabilitätsanalyse nicht-linearer Systeme mit linearer Optimierung." Gerhard-Mercator-Universitaet Duisburg, 2002. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-02152002-111745/.
Full textQu, Yuhui. "Periodic Motions and Stability Analysis of a Non-linear Rotating Beam Subjected to Torsional Excitation." Thesis, Southern Illinois University at Edwardsville, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1565859.
Full textThe periodic motions and stability of a nonlinear rotating beam subjected to a torsional excitation is investigated in this thesis. Both quadratic and cubic geometric stiffening nonlinearities are retained in the equation of motion, and the reduced model is obtained via the Galerkin method. Saddle-node bifurcations and Hopf bifurcations of the Period-1 motions of the model were obtained via the high order harmonic balance method. The period-2 and period-4 solutions, which are emanated from the period-1 and period-2 motions, respectively, are obtained by the combined implementation of the harmonic balance method, Floquet theory, and Discrete Fourier Transform (DFT). Stabilities are detected by Floquet theory. Stable and unstable periodic motions are illustrated from numerical and analytical solutions. The analytical periodic solutions and their stabilities are verified through numerical simulation.
Stirner, Tobias [Verfasser], and Georg [Akademischer Betreuer] Raffelt. "Fast neutrino flavour conversions : Stability analysis in the linear regime / Tobias Stirner ; Betreuer: Georg Raffelt." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1218465859/34.
Full textSuliman, Ridhwaan. "A quadratic non-linear elasticity formulation for the dynamic behaviour of fluid-loaded structures." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277824.
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