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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723482076
Category :
Languages : en
Pages : 180
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Book Description
Probabilistic finite element methods (PFEM), synthesizing the power of finite element methods with second-moment techniques, are formulated for various classes of problems in structural and solid mechanics. Time-invariant random materials, geometric properties and loads are incorporated in terms of their fundamental statistics viz. second-moments. Analogous to the discretization of the displacement field in finite element methods, the random fields are also discretized. Preserving the conceptual simplicity, the response moments are calculated with minimal computations. By incorporating certain computational techniques, these methods are shown to be capable of handling large systems with many sources of uncertainties. By construction, these methods are applicable when the scale of randomness is not very large and when the probabilistic density functions have decaying tails. The accuracy and efficiency of these methods, along with their limitations, are demonstrated by various applications. Results obtained are compared with those of Monte Carlo simulation and it is shown that good accuracy can be obtained for both linear and nonlinear problems. The methods are amenable to implementation in deterministic FEM based computer codes. Belytschko, T. and Liu, W. K. and Mani, A. and Besterfield, G. Unspecified Center DYNAMIC STRUCTURAL ANALYSIS; ELASTOPLASTICITY; FINITE ELEMENT METHOD; SOLID MECHANICS; VARIATIONAL PRINCIPLES; DISPLACEMENT; LOADS (FORCES); MONTE CARLO METHOD; NONLINEARITY; PROBABILITY THEORY...
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723482076
Category :
Languages : en
Pages : 180
Get Book Here
Book Description
Probabilistic finite element methods (PFEM), synthesizing the power of finite element methods with second-moment techniques, are formulated for various classes of problems in structural and solid mechanics. Time-invariant random materials, geometric properties and loads are incorporated in terms of their fundamental statistics viz. second-moments. Analogous to the discretization of the displacement field in finite element methods, the random fields are also discretized. Preserving the conceptual simplicity, the response moments are calculated with minimal computations. By incorporating certain computational techniques, these methods are shown to be capable of handling large systems with many sources of uncertainties. By construction, these methods are applicable when the scale of randomness is not very large and when the probabilistic density functions have decaying tails. The accuracy and efficiency of these methods, along with their limitations, are demonstrated by various applications. Results obtained are compared with those of Monte Carlo simulation and it is shown that good accuracy can be obtained for both linear and nonlinear problems. The methods are amenable to implementation in deterministic FEM based computer codes. Belytschko, T. and Liu, W. K. and Mani, A. and Besterfield, G. Unspecified Center DYNAMIC STRUCTURAL ANALYSIS; ELASTOPLASTICITY; FINITE ELEMENT METHOD; SOLID MECHANICS; VARIATIONAL PRINCIPLES; DISPLACEMENT; LOADS (FORCES); MONTE CARLO METHOD; NONLINEARITY; PROBABILITY THEORY...
Author: Abraham I. Beltzer
Publisher:
ISBN: 9780387515984
Category : Calculus of variations
Languages : en
Pages : 0
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Book Description
The variational approach, including the direct methods and finite elements, is one of the main tools of engineering analysis. However, it is difficult to appreciate not only for seniors but for graduate students too. It is possible to make this subject easier to understand with the help of symbolic manipulation codes (SMC). The easiness with which these codes provide analytical results allow for a student or researcher to focus on the ideas rather than on calculational difficulties. The very process of programming with SMC encourages appreciation of the qualitative aspects of investigations. Saving time and effort, they enable undergraduates to deal with the subjects generally regarded as graduate courses. There is a habitual aspect too. These days it is more convenient for a student (researcher) to work with a keyboard than with a pencil. Moreover, semantic features of the codes may allow for generalizations of the standard techniques, which would be impossible to achieve without the computer's help. Publsiher's note.
Author: Ted Belytschko
Publisher:
ISBN:
Category :
Languages : en
Pages : 64
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Book Description
Author: Gérard Meunier
Publisher: John Wiley & Sons
ISBN: 0470393807
Category : Science
Languages : en
Pages : 618
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Book Description
Written by specialists of modeling in electromagnetism, this book provides a comprehensive review of the finite element method for low frequency applications. Fundamentals of the method as well as new advances in the field are described in detail. Chapters 1 to 4 present general 2D and 3D static and dynamic formulations by the use of scalar and vector unknowns and adapted interpolations for the fields (nodal, edge, face or volume). Chapter 5 is dedicated to the presentation of different macroscopic behavior laws of materials and their implementation in a finite element context: anisotropy and hysteretic properties for magnetic sheets, iron losses, non-linear permanent magnets and superconductors. More specific formulations are then proposed: the modeling of thin regions when finite elements become misfit (Chapter 6), infinite domains by using geometrical transformations (Chapter 7), the coupling of 2D and 3D formulations with circuit equations (Chapter 8), taking into account the movement, particularly in the presence of Eddy currents (Chapter 9) and an original approach for the treatment of geometrical symmetries when the sources are not symmetric (Chapter 10). Chapters 11 to 13 are devoted to coupled problems: magneto-thermal coupling for induction heating, magneto-mechanical coupling by introducing the notion of strong and weak coupling and magneto-hydrodynamical coupling focusing on electromagnetic instabilities in fluid conductors. Chapter 14 presents different meshing methods in the context of electromagnetism (presence of air) and introduces self-adaptive mesh refinement procedures. Optimization techniques are then covered in Chapter 15, with the adaptation of deterministic and probabilistic methods to the numerical finite element environment. Chapter 16 presents a variational approach of electromagnetism, showing how Maxwell equations are derived from thermodynamic principles.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 836
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Book Description
Author: Isaac Elishakoff
Publisher: Oxford University Press, USA
ISBN: 9780198526315
Category : Language Arts & Disciplines
Languages : en
Pages : 282
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Book Description
The finite element method (FEM) can be successfully applied to various field problems in solid mechanics, fluid mechanics and electrical engineering. This text discusses finite element methods for structures with large stochastic variations.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 230
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Book Description
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722699604
Category :
Languages : en
Pages : 62
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Book Description
An overview of the probabilistic finite element method (PFEM) developed by the authors and their colleagues in recent years is presented. The primary focus is placed on the development of PFEM for both structural mechanics problems and fracture mechanics problems. The perturbation techniques are used as major tools for the analytical derivation. The following topics are covered: (1) representation and discretization of random fields; (2) development of PFEM for the general linear transient problem and nonlinear elasticity using Hu-Washizu variational principle; (3) computational aspects; (4) discussions of the application of PFEM to the reliability analysis of both brittle fracture and fatigue; and (5) a stochastic computational tool based on stochastic boundary element (SBEM). Results are obtained for the reliability index and corresponding probability of failure for: (1) fatigue crack growth; (2) defect geometry; (3) fatigue parameters; and (4) applied loads. These results show that initial defect is a critical parameter. Belytschko, Ted and Liu, Wing Kam Unspecified Center...
Author: Prakash Mahadeo Dixit
Publisher: Elsevier
ISBN: 0443333904
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
An Introduction to the Finite Element Method with the Variational Approach offers a comprehensive solution to the gaps often found in introductory texts on the Finite Element Method (FEM). It provides a thorough introduction to the fundamental principles of linear and time-independent FEM within the variational framework. The book meticulously covers the derivation of 1-D FEM equations based on variational functionals, encompassing both linear and higher-order elements, and shape functions driven by convergence criteria. Furthermore, it explores 1-D numerical integration, outlines coding procedures, and provides insights into handling material nonlinearity and time-dependent scenarios. Expanding into 2-D problems, the book offers derivations of 2-D FEM equations tailored to diverse engineering disciplines, including Steady-State Heat Conduction, Solid Mechanics (covering torsion, plane strain/axisymmetric cases, and the bending, stability, and vibrations of thin plates), as well as Fluid Mechanics (addressing incompressible inviscid and viscous fluids). It includes detailed discussions on element continuity, numerical integration techniques, and even includes 2-D codes for selected problems. The book concludes by delving into recent advancements in FEM, with a specific focus on applications in machine learning and isogeometric analysis. This resource is indispensable for students and practitioners seeking a deeper and more conceptual understanding of FEM, providing a robust foundation for their endeavours. Explains the fundamentals of the Finite Element Method (FEM) with a focus on the linear and time-independent aspects, employing a variational approach Covers variational FEM formulations for 1-D and 2-D scenarios in solid mechanics, fluid mechanics, and heat conduction problems Explores the application of 1-D Galerkin FEM to address challenges presented by material nonlinearity and time-dependent problems Delves into the intricacies of FEM algorithms and provides a comprehensive overview of coding implementation Offers insight into Machine Learning and includes a section on Isogeometric analysis
Author: Nicola Bellomo
Publisher: Springer Science & Business Media
ISBN: 3642847897
Category : Science
Languages : en
Pages : 546
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Book Description
The Symposium, held in Torino (lSI, Villa Gualino) July 1-5, 1991 is the sixth of a series of IUTAM-Symposia on the application of stochastic analysis to continuum and discrete mechanics. The previous one, held in Innsbruck (1987), was mainly concentrated on qual itative and quantitative analysis of stochastic dynamical systems as well as on bifurcation and transition to chaos of deterministic systems. This Symposium concentrated on fundamental aspects (stochastic analysis and mathe matical methods), on specific applications in various branches of mechanics, engineering and applied sciences as well as on related fields as analysis of large systems, system identifica tion, earthquake prediction. Numerical methods suitable to provide quantitative results, say stochastic finite elements, approximation of probability distribution and direct integration of differential equations have also been the object of interesting presentations. Specific topics of the sessions have been: Engineering Applications, Equivalent Lineariza tion of Discrete Stochastic Systems, Fatigue and Life Estimation, Fluid Dynamics, Numerical Methods, Random Vibration, Reliability Analysis, Stochastic Differential Equations, System Identification, Stochastic Control. We are indebted to the IUTAM Bureau for having promoted and sponsored this Sympo sium and the Scientific Committee for having collaborated to the selection of participants and lecturers as well as to a prompt reviewing of the papers submitted for publication into these proceedings. A special thank is due to Frank Kozin: the organization of this meeting was for him ';ery important; he missed the meeting but his organizer ability was present.
