Author: C.W. Cai, J.K. Liu | Size: 5.75 MB | Format:PDF | Quality:Unspecified | Publisher: World Scientific Pub Co Inc | Year: 2002 | pages: 280 | ISBN: 9789810249281
By using the U-transformation method, it is possible to uncouple linear simultaneous equations, either algebraic or differential, with cyclic periodicity. This text presents a procedure for applying the U-transformation technique twice to uncouple the two sets of unknown variables in a doubly periodic structure to achieve an analytical exact solution. Explicit exact solutions for the static and dynamic analyses for certain engineering structures with doubly periodic properties - such as a continuous truss with any number of spans, cable network and grillwork on supports with periodicity, and grillwork with periodic stiffening members or equidistant line supports - can be found in the volume. The availability of these exact solutions not only helps with the checking of the convergence and accuracy of numerical solutions, but also provides a basis for optimization design for these types of structures. The study of the force vibration and mode shape of periodic systems with non-linear disorder is yet another research area which has attained considerable success by the U-transformation method. This work illustrates the analytical approach and procedure for the problems of localization of the mode shape of nearly periodic systems together with the results.
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Author: John Sharp | Size: 23.5 MB | Format:PDF | Quality:Original preprint | Publisher: authorization of Microsoft Corporation | Year: 2012 | pages: 844 | ISBN: 978-0-7356-6801-0
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Author: Dr Noel O’Dowd | Size: 3.7 MB | Format:PDF | Quality:Original preprint | Publisher: Imperial College London | Year: 2002 | pages: 107
Fracture mechanics concerns the design and analysis of structures which contain cracks or flaws. On some size-scale all materials contain flaws either microscopic, due to cracked inclusions, debonded fibres etc., or macroscopic, due to corrosion, fatigue, welding flaws etc. Thus fracture mechanics is involved in any detailed design or safety assessment of a structure. As cracks can grow during service due to e.g. fatigue, fracture mechanics assessments are required throughout the life of a structure or component, not just at start of life. Fracture mechanics answers the questions: What is the largest sized crack that a structure can contain or the largest load the structure can bear for failure to be avoided? How long before a crack which was safe becomes unsafe? What material should be used in a certain application to ensure safety?
Studies in the US in the 1970s by the US National Bureau of Standards estimated that “cost of fracture” due to accidents, overdesign of structures, inspection costs, repair and replacement was on the order of 120 billion dollars a year. While fracture cannot of course be avoided, they estimated that, if best fracture control technology at the time was applied, 35 billion dollars could be saved annually. This indicates the importance of fracture mechanics to modern industrialised society.
The topics of linear elastic fracture mechanics, elastic-plastic fracture mechanics and high temperature fracture mechanics (creep crack growth) are dealt with in this course. The energy release rate method of characterising fracture is introduced and the K and HRR fields which characterise the crack tip fields under elastic and plastic/creep fracture respectively are derived. The principal mechanisms of fracture which control failure in the different regimes are also discussed. In the later part of the course, the application of these fracture mechanics principles in the assessment of the safety of components or structures with flaws through the use of standardised procedures is discussed.
The approach taken in this course is somewhat different from that in Fundamentals of Fracture Mechanics (FFM) as here more emphasis is put on the mechanics involved and outlines of mathematical proofs of some of the fundamental fracture mechanics relationships are provided. There is some revision of the topics covered in FFM, particularly in the area of linear elastic fracture mechanics though the approach is a little different.
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Flexibility in Engineering Design (Engineering Systems)
Author: Richard de Neufville, Stefan Scholtes, | Size: 2.8 MB | Format:PDF | Quality:Unspecified | Publisher: The MIT Press | Year: 2011 | pages: 311 | ISBN: 9780262016230
Project teams can improve results by recognizing that the future is inevitably uncertain and that by creating flexible designs they can adapt to eventualities. This approach enables them to take advantage of new opportunities and avoid harmful losses. Designers of complex, long-lasting projects--such as communication networks, power plants, or hospitals--must learn to abandon fixed specifications and narrow forecasts. They need to avoid the "flaw of averages," the conceptual pitfall that traps so many designs in underperformance. Failure to allow for changing circumstances risks leaving significant value untapped. This book is a guide for creating and implementing value-enhancing flexibility in design. It will be an essential resource for all participants in the development and operation of technological systems: designers, managers, financial analysts, investors, regulators, and academics. The book provides a high-level overview of why flexibility in design is needed to deliver significantly increased value. It describes in detail methods to identify, select, and implement useful flexibility. The book is unique in that it explicitly recognizes that future outcomes are uncertain. It thus presents forecasting, analysis, and evaluation tools especially suited to this reality. Appendixes provide expanded explanations of concepts and analytic tools.
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Funding for Phases I and II of the SAC Steel Program to Reduce the Earthquake Hazards of Steel Moment-Frame Structures was principally provided by the Federal Emergency Management Agency, with ten percent of the Phase I program funded by the State of California, Office of Emergency Services. Substantial additional support, in the form of donated materials, services, and data has been provided by a number of individual consulting engineers, inspectors, researchers, fabricators, materials suppliers and industry groups. Special efforts have been made to maintain a liaison with the engineering profession, researchers, the steel industry, fabricators, code-writing organizations and model code groups, building officials, insurance and risk-management groups, and federal and state agencies active in earthquake hazard mitigation efforts. SAC wishes to acknowledge the support and participation of each of the above groups, organizations and individuals. In particular, we wish to acknowledge the contributions provided by the American Institute of Steel Construction, the Lincoln Electric Company, the National Institute of Standards and Technology, the National Science Foundation, and the Structural Shape Producers Council. SAC also takes this opportunity to acknowledge the efforts of the project participants - the managers, investigators, writers, and editorial and production staff - whose work has contributed to the development of these documents. Finally, SAC extends special acknowledgement to Mr. Michael Mahoney, FEMA Project Officer, and Dr. Robert Hanson, FEMA Technical Advisor, for their continued support and contribution to the success of this effort.
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This book offers a broad overview of the potential of continuum mechanics to describe a wide range of macroscopic phenomena in real-world problems. Building on the fundamentals presented in the authors’ previous book, Continuum Mechanics using Mathematica®, this new work explores interesting models of continuum mechanics, with an emphasis on exploring the flexibility of their applications in a wide variety of fields.
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Author: Carl H. Popelar, Melvin F. Kanninen | Size: 7 MB | Format:DjVu | Quality:Unspecified | Publisher: Oxford University Press, USA | Year: 1985 | pages: 578 | ISBN: 9780195035322
This book presents an extensive, unified, and up-to-date approach to the still developing subject of fracture mechanics from an applied mechanics perspective. Progressing from the simple to the more advanced topics, it goes beyond the well developed area of linear elastic fracture mechanics to consider the dynamic and elastic-plastic regimes, and in doing so, extends the subject into a broader range of realistic engineering applications.
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