George C. Sih

What can be added to the fracture mechanics of metal fatigue that has not already been said since the 1900s? From the view point of the material and structure engineer, there are many aspects of failure by fatigue that are in need of attention, particularly when the size and time of the working components are changed by orders of magnitude from those considered by st traditional means. The 21 century marks an era of technology transition where structures are made larger and devices are made smaller, rendering the method of destructive testing unpractical. While health monitoring entered the field of science and engineering, the practitioners are discovering that the correlation between the signal and the location of interest depends on a priori knowledge of where failure may initiate. This information is not easy to find because the integrity of the physical system will change with time. Required is software that can self-adjust in time according to the monitored data. In this connection, effective application of health monitoring can use a predictive model of fatigue crack growth. Earlier fatigue crack growth models assumed functional dependence on the maximum stress and the size of the pre-existing crack or defect. Various possibilities were examined in the hope that the data could be grouped such that linear interpolation would apply.

Fatigue Crack Growth Behaviour of Small and Large Bodies

Multiscale Fatigue Crack Initiation and Propagation of Engineering Materials: Structural Integrity and Microstructural Worthiness

Shang-Ching Chou

J. Michopoulos

This book contains results of more than a decade's effort on coupled deformation and diffusion obtained in research performed at the Institute of Fracture and Solid Mechanics, Lehigh University. Despite the overwhelming number of theories on this subject, little is known on the assessment of coupling effects because of the inherent difficulties associated with experimentation. A case in point is couple thermoelasticity, a theory that has remained virtually unused in practice. This is indicative of the inadequacy of conventional approaches. The interdependence of heat, moisture and deformation arises in many engineer ing problems of practical interest. Whether these effects are coupled or not depend on the transient character of the boundary conditions. Special attention is given to finding the coupling constants. Invoked is the assumption that the physical parameters should be independent of the specified boundary conditions. They can thus be extracted from known experimental data for situations where coupling effects are relatively weak and then applied to predict strong coupling effects as boundary conditions are altered. This is illustrated for the T300/5208 material commonly used in composites and permits a more reliable evaluation of material behaving under extreme environmental conditions. The lack of this knowledge can often be a major deterrent to the achievement of new technological advances. The reader will recognize that the material in this book does not follow the main stream of research on moisture-temperature diffusion and deformation.

Hygrothermoelasticity

This third volume of a series on Mechanies of Fraeture deals with eraeks in plates and shelIs. It was noted in Volume 2 on three-dimensional eraek problems that additional free surfaees can lead to substantial mathematical complexities, often making the analysis unmanageable. The theory of plates and shelIs forms a part of the theory of elasticity in which eertain physieal assumptions are made on the basis that the distanee between two bounded surfaees, either fiat or eurved, is small in eomparison with the overall dimen sions of the body. In modern times, the broad and frequent applieations of plate- and shell-like struetural members have aeted as a stimulus to whieh engineers and researchers in the field of fracture meehanies have responded with a wide variety of solutions of teehnieal importanee. These eontributions are covered in this book so that the reader may gain an understanding of how analytieal treat me nt s ofplates and shells containing initial imperfeetions in the form of eraeks are earried out. The development of plate and shell theories has involved long standing controversy on the eonsisteney of omitting eertain small terms and at the same time retaining others of the same order of magnitude. This defieieney depends on the ratio of the plate or shell thiekness, h, to other eharaeteristie dimensions and eannot be eompletely resolved in view of the approximations inherent in the transverse dependence of the extensional and bending stresses.

A collection of stress intensity factor solutions for cracks in plates and shells

Plates and shells with cracks

Alberto Carpinteri

G. Surace

The last decade has seen a significant growth in the processing and fabrication of advanced composite materials. This volume contains the up-to-date contributions of those with working experience in the automotive, marine, aerospace and construction field. Starting with modern technologies concerned with assessing the change in material microstructure in terms of the processing parameters, methodologies are offered to account for tradeoffs between the fundamental variables such as temperature and pressure that control the product quality. The book contains new ideas and data, not available in the open literature.

Applications to the Automotive, Marine, Aerospace and Construction Industry

Advanced Technology for Design and Fabrication of Composite Materials and Structures

A.J. Ishlinsky

S.T. Mileiko

More than six years ago, several of Rabotnov's close friends and colleagues from the USSR and USA decided to contribute a volume on Plasticity and Failure of Solids in honor of his 70th birthday. The celebration was interrupted unexpectedly by his death on May 13, 1985 at which time another decision was made still to publish the work, but as a memorial volume. As in any field of scientific endeavor, research confronts the scientists with anomalies; our chosen area is no exception. The ways in which failure criteria and plasticity theory are combined can differ widely among the researchers; they will never yield quite the same results. Each of the invited contributors has, therefore, been encouraged to express his views and to expound on his personal opinion. The contributors are free of enumeration from the authority and/or consensus of any scientific society or community. What impedes scientific process is the esoteric tradition of accepting ideas and theories by consensus among members of societies and communities. The absence of such a trend is refreshing; the collaboration between the authors from the USSR and the USA had to be one of the contributing factors. Finally, the editors wish to acknowledge the authors who have made the publication of this volume possible. a. c. Sib S. T. Mileiko AJ. Ishlinsky xi The late Professor Yuriy Nickolaevich Rabotnov (February 24, 1914 - May 13, 1985) xii Scientific biography of the late academician Yu. N.

Memorial volume dedicated to the late Professor Yuriy Nickolaevich Rabotnov

Plasticity and failure behavior of solids

H. Zorski

An International Symposium on Defects and Fracture was held in Tuczno, Poland, 13-17 October 1980 under the sponsorship of the Polish Academy of Sci ences and Institute of Fracture and Solid Mechanics, Lehigh University. Profes sor H. Zorski of the Academy and Professor G. C. Sih of Lehigh University were Co-Chairmen. The idea for the Symposium was initiated by the members of the Organizing Committee: G. C. Sih (Co-Chairman), H. Zorski (Co-Chairman), M. Matczynski (Secretary), D. R. Axelrad, R. Bullough, J. W. Provan and R. deWit. With the rapid development of high performance materials and their increasing use in vital structural applications, there is a need for a more in-depth under standing of the fundamentals associated with material behavior and failure. Al though this topic encompasses a wide range of disciplines, it is appropriate to narrow the discussion to material failures initiating from inherent, unavoidable defects or cracks. A balanced coverage of analysis and physics was achieved by inviting speakers with backgrounds in applied mechanics and solid state physics. The input was limited to a small group of specialists who had the opportunity to discuss not only past progress but also ideas for future research.

Proceedings of First International Symposium on Defects and Fracture, held at Tuczno, Poland, October 13–17, 1980

Defects and Fracture

N. Ryan

R. Jones

The International Conference on Fracture Mechanics Technology Applied to Material Evaluation and Structure Design was held in Melbourne, Australia, from August 10 to 13, 1982. It was sponsored jointly by the Australian Fracture Group and Institute of Fracture and Solid Mechanics at Lehigh University. Pro fessor G. C. Sih of Lehigh University, Drs. N. E. Ryan and R. Jones of Aeronau tical Research Laboratories served as Co-Chairmen. They initiated the organiza tion of this international event to provide an opportunity for the practitioners, engineers and interested individuals to present and discuss recent advances in the evaluation of material and structure damage originating from defects or cracks. Particular emphases were placed on applying the fracture mechanics tech nology for assessing interactions between material properties, design and opera tional requirements. It is timely to hold such a Conference in Australia as she embarks on technology extensive industries where safeguarding structures from pre mature and unexpected failure is essential from both the technical and economical points. view The application of system-type approach to failure control owes much of its success to fracture mechanics. It is now generally accepted that the discipline, when properly implemented, provides a sound engineering basis for accounting in teractions between material properties, design, fabrication, inspection and op erational requirements. The approach offers effective solutions for design and maintenance of large-scale energy generation plants, mining machineries, oil ex ploration and retrieval equipments, land, sea and air transport vehicles.

Proceedings of an International Conference on ‘Fracture Mechanics Technology Applied to Material Evaluation and Structure Design’, held at the University of Melbourne, Melbourne, Australia, August 10–13, 1982

George C. Sih

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