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An Integrated Method For The Transient Solution Of Reduced Order Models Of Geometrically Nonlinear Structural Dynamic Systems
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Book Synopsis An Integrated Method for the Transient Solution of Reduced Order Models of Geometrically Nonlinear Structural Dynamic Systems by : Fritz Adrian Lülf
Download or read book An Integrated Method for the Transient Solution of Reduced Order Models of Geometrically Nonlinear Structural Dynamic Systems written by Fritz Adrian Lülf and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: For repeated transient solutions of geometrically nonlinear structures the numerical effort often poses a major obstacle. Thus, the introduction of a reduced order model, which takes the nonlinear effects into account and accelerates the calculations considerably, is often necessary.This work yields a method that allows for rapid, accurate and parameterisable solutions by means of a reduced model of the original structure. The structure is discretised and its dynamic equilibrium described by a matrix equation. The projection on a reduced basis is introduced to obtain the reduced model. A comprehensive numerical study on several common reduced bases shows that the simple introduction of a constant basis is not sufficient to account for the nonlinear behaviour. Three requirements for an rapid, accurate and parameterisable solution are derived. The solution algorithm has to take into account the nonlinear evolution of the solution, the solution has to be independent of the nonlinear finite element terms and the basis has to be adapted to external parameters.Three approaches are provided, each responding to one requirement. These approaches are assembled to the integrated method. The approaches are the update and augmentation of the basis, the polynomial formulation of the nonlinear terms and the interpolation of the basis. A Newmark-type time-marching algorithm provides the frame of the integrated method. The application of the integrated method on test-cases with geometrically nonlinear finite elements confirms that this method leads to the initial aim of a rapid, accurate and parameterisable transient solution.
Book Synopsis Structural Dynamic Systems Computational Techniques and Optimization by : Cornelius T. Leondes
Download or read book Structural Dynamic Systems Computational Techniques and Optimization written by Cornelius T. Leondes and published by CRC Press. This book was released on 1999-05-11 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear structural dynamic systems which are multi-degree of freedom systems involve, for instance, matrix dynamic equilibrium equations, which can be of various order up to very high order. In these equations, the nonlinear quantities can be dependent on time and other terms, such as scalar variables, which are dependent on time. Frequency response and response time derivatives would also, of course, be involved. Nonlinear terms can account for dissipative phenomena and can be due to other physical phenomena. In fact, many engineering structures involve time-dependent properties such as, stiffness elements of specific structural components which can change according to the stress level. Other examples of dynamic elements of nonlinear structural systems can include system mass and damping distribution elements which evolve with time, such as railway or highway bridges and other structures, which interact with external agencies generating the system motion (for example, trains, a queue of vehicles, or other external agencies.) This volume is a rather comprehensive treatment of many of the techniques and methods which are utilized for the analysis of nonlinear structural dynamic systems.
Book Synopsis Reduced-order Models for Geometrically Nonlinear Vibrations of Thin Structures by : Yichang Shen
Download or read book Reduced-order Models for Geometrically Nonlinear Vibrations of Thin Structures written by Yichang Shen and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When vibrating with large amplitudes, thin structures experience geometric nonlinearity due to the nonlinear relationship between strains and displacements. Because full-order nonlinear analysis on geometrically nonlinear models are computationally very expensive, the derivation of efficient reduced-order models (ROMs) has always been a topic of interest.In this thesis, nonlinear reduction methods for building ROMs with geometric nonlinearity in the framework of the Finite Element (FE) procedure, are investigated. Three non-intrusive nonlinear reduction methods are specifically investigated and systematically compared. They are: implicit condensation and expansion (ICE), modal derivatives (MD), and the reduction to invariant manifold. Theoretical analysis shows that the first two methods can give reliable results only if a slow/fast assumption between slave and master coordinates holds. On the other hand, reduction to invariant manifolds allows proposing a simulation-free reduction method that can be applied without restricting assumptions on the frequencies of the slave modes.Numerical comparisons and numerous applications to continuous structures discretized with the FE procedure, are given subsequently. For application of the invariant manifold-based method, the computation is based on a direct application of the normal form to the physical space and hence to the nodes of the FE mesh, a method recently developed. The examples show the advantages and drawbacks of each reduction method when deriving ROM, and the results of the theoretical comparison are validated.Finally, the analysis of the dynamics of a system with 1:2 internal resonance and cubic nonlinearity is given in the last part of the thesis. The real normal form of the problem is first derived. Then the solution branches of the problem are investigated and compared to simpler solutions with the dynamics truncated at order two. The divergent behaviour of the hardening/softening characteristics for single-mode reduction is investigated with this more complete model.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reduced Order Modeling Of Stochastic Dynamic Systems by :
Download or read book Reduced Order Modeling Of Stochastic Dynamic Systems written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Uncertainties in both loading and structural characteristics can adversely affect the response and reliability of a structure. Parameter uncertainties in structural dynamics can arise due to several sources. These include variations due to intrinsic material property variability, measurement errors, manufacturing and assembly errors, differences in modeling and solution procedures. Problems of structural dynamics with randomly distributed spatial inhomogeneities in elastic, mass, and damping properties, have been receiving wide attention. Several mathematical and computational issues include discretization of random fields, characterization of random eigensolutions, inversion of random matrices, solutions of stochastic boundary-value problems, and description of random matrix products. Difficulties are encountered when one has to include interaction between nonlinear and stochastic system characteristics, or if one is interested in controlling the system response. The study of structural systems including the effects of system nonlinearity in the presence of parameter uncertainties presents serious challenges and difficulties to designers and reliability engineers. In the analysis of large structures, the situation for substructuring frequently arises due to the repetition of identical assemblages (substructures), within a structure, and the general need to reduce the size of the problem, particularly in the case of non-linear inelastic dynamic analysis. A small reduction in the model size can have a large effect on the storage and time requirement. A primary structural dynamic system may be coupled to subsystems such as piping systems in a nuclear reactor or in a chemical plant. Usually subsystem in itself is quite complex and its modeling with finite elements may result in a large number of degrees of freedom. The reduced subsystem model should be of low-order yet capturing the essential dynamics of the subsystem for useful integration with the primary structure.
Book Synopsis Technology for Large Space Systems by :
Download or read book Technology for Large Space Systems written by and published by . This book was released on 1989 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microelectromechanical Systems written by and published by . This book was released on 2007 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Structural Failure Analysis and Prediction Methods for Aerospace Vehicles and Structures by : Sook-Ying Ho
Download or read book Structural Failure Analysis and Prediction Methods for Aerospace Vehicles and Structures written by Sook-Ying Ho and published by Bentham Science Publishers. This book was released on 2010 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with structural failure (induced by mechanical, aerodynamic, acoustic and aero-thermal, loads, etc.) of modern aerospace vehicles, in particular high-speed aircraft, solid propellant rocket systems and hypersonic flight vehicles, where structural integrity, failure prediction and service life assessment are particularly challenging, due to the increasingly more demanding mission requirements and the use of non-traditional materials, such as non-metallic composites, in their construction. Prediction of the complex loading environment seen in high-speed operation and constitutive / fracture models which can adequately describe the non-linear behaviour exhibited by advanced alloys and composite materials are critical in analyzing the non-linear structural response of modern aerospace vehicles and structures. The state-of-the-art of the different structural integrity assessment and prediction methodologies (including non-destructive structural health monitoring techniques) used for the structural design, service life assessment and failure analysis of the different types of aerospace vehicles are presented. The chapters are written by experts from aerospace / defence research organizations and academia in the fields of solid mechanics, and structural mechanics and dynamics of aircraft, rocket and hypersonic systems. The book will serve as a useful reference document containing specialist knowledge on appropriate prediction methodologies for a given circumstance and experimental data acquired from multi-national collaborative programs.
Book Synopsis Innovative Approaches in Computational Structural Engineering by : George C. Tsiatas
Download or read book Innovative Approaches in Computational Structural Engineering written by George C. Tsiatas and published by Frontiers Media SA. This book was released on 2020-04-22 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nowadays, numerical computation has become one of the most vigorous tools for scientists, researchers and professional engineers, following the enormous progress made during the last decades in computing technology, in terms of both computer hardware and software development. Although this has led to tremendous achievements in computer-based structural engineering, the increasing necessity of solving complex problems in engineering requires the development of new ideas and innovative methods for providing accurate numerical solutions in affordable computing times. This collection aims at providing a forum for the presentation and discussion of state-of-the-art innovative developments, concepts, methodologies and approaches in scientific computation applied to structural engineering. It involves a wide coverage of timely issues on computational structural engineering with a broad range of both research and advanced practical applications. This Research Topic encompasses, but is not restricted to, the following scientific areas: modeling in structural engineering; finite element methods; boundary element methods; static and dynamic analysis of structures; structural stability; structural mechanics; meshless methods; smart structures and systems; fire engineering; blast engineering; structural reliability; structural health monitoring and control; optimization; and composite materials, with application to engineering structures.
Book Synopsis Structural Dynamics Branch Research and Accomplishments to FY 1992 by :
Download or read book Structural Dynamics Branch Research and Accomplishments to FY 1992 written by and published by . This book was released on 1992 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1048 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA SP. written by and published by . This book was released on 1985 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Abstract Journal in Earthquake Engineering by :
Download or read book Abstract Journal in Earthquake Engineering written by and published by . This book was released on 1991 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Substructuring in Engineering Dynamics by : Matthew S. Allen
Download or read book Substructuring in Engineering Dynamics written by Matthew S. Allen and published by Springer. This book was released on 2019-08-01 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the most common state-of-the art methods for substructuring and model reduction and presents a framework that encompasses most method, highlighting their similarities and differences. For example, popular methods such as Component Mode Synthesis, Hurty/Craig-Bampton, and the Rubin methods, which are popular within finite element software, are reviewed. Similarly, experimental-to-analytical substructuring methods such as impedance/frequency response based substructuring, modal substructuring and the transmission simulator method are presented. The overarching mathematical concepts are reviewed, as well as practical details needed to implement the methods. Various examples are presented to elucidate the methods, ranging from academic examples such as spring-mass systems, which serve to clarify the concepts, to real industrial case studies involving automotive and aerospace structures. The wealth of examples presented reveal both the potential and limitations of the methods.
Book Synopsis Reduced Order Methods for Modeling and Computational Reduction by : Alfio Quarteroni
Download or read book Reduced Order Methods for Modeling and Computational Reduction written by Alfio Quarteroni and published by Springer. This book was released on 2014-06-05 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph addresses the state of the art of reduced order methods for modeling and computational reduction of complex parametrized systems, governed by ordinary and/or partial differential equations, with a special emphasis on real time computing techniques and applications in computational mechanics, bioengineering and computer graphics. Several topics are covered, including: design, optimization, and control theory in real-time with applications in engineering; data assimilation, geometry registration, and parameter estimation with special attention to real-time computing in biomedical engineering and computational physics; real-time visualization of physics-based simulations in computer science; the treatment of high-dimensional problems in state space, physical space, or parameter space; the interactions between different model reduction and dimensionality reduction approaches; the development of general error estimation frameworks which take into account both model and discretization effects. This book is primarily addressed to computational scientists interested in computational reduction techniques for large scale differential problems.
Book Synopsis Efficient Nonlinear Transient Dynamic Analysis for Structural Optimization Using an Exact Integral Equation Formulation by : Joshua H. Gordis
Download or read book Efficient Nonlinear Transient Dynamic Analysis for Structural Optimization Using an Exact Integral Equation Formulation written by Joshua H. Gordis and published by . This book was released on 1999 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report serves to document progress made to date on the National Science Foundation Project #97-13481, Earthquake Hazard Mitigation Program. The focus of this phase of the project is the development of an improved solution algorithm for fast transient analysis of large, locally nonlinear structures using time domain structural synthesis. The report documents the development of several algorithms intended to improve upon the original algorithm developed by the first author. The last algorithm developed meets the stated goals of the project. This algorithm is a newly developed recursive, block by block convolution solution to the governing nonlinear integral equation. As is demonstrated with a realistically large nonlinear base excitation problem (51, 300 DOF finite element model), the new algorithm provides a 78% reduction in time required for the nonlinear transient base excitation solution, as compared with traditional direct integration. The new algorithm provides an even greater reduction in computer time for subsequent analysis. The nonlinear base isolation solutions calculated using the new algorithm take approximately 7 seconds, as compared with the direct integration solution which takes approximately 30 minutes. The rapid reanalysis capability will facilitate the development of numerical optimization for the design of nonlinear isolation. The theory of transient synthesis is documented, along with a new proof of the exponential convergence properties of an iterative solution to the governing nonlinear integral equation.
