The Effect Of Stress Concentration On The Fracture And Deformation Characteristics Of Ceramics And Metals

The effects of non-uniform stress distributions on fracture strength were studied on four mate rials that exhibit brittle behavior; Wesgo AL995, Mykroy 750 and 1100 (ceramics) and Plexiglas (acrylic plastic). Analysis of the results of both notch tensile and bend tests on these materials indicate that fracture in ceramic materials can be explained by a maximum fracture stress concept provided that the inherent inhomogeneity of these materials is considered in the analysis. Weibull's statistical theory of fracture appears to be ap plicable to the analysis of inhomogeneity. The be havior of Plexiglas is similar to that previously observed for high strength metals. Studies of plastic flow in metallic flat notch tensile speci mens indicate that the distribution of the princi pal longitudinal strain across the notch section is related to the distribution of the longitudinal elastic stress raised to the power b, where b is primarily a function of the strain hardening ex ponent of the material. Also, Neuber's conclusion that K sub t represents the geometric mean of the true stress and true strain concentration factors in pure shear seems generally applicable to the plane stress tension case.

As the shift from the Metal Age progresses, materials engineers and materials scientists seek new analytical and design methods to create stronger and more reliable materials. Based on extensive research and developmental work done at the author’s multi-disciplinary material laboratory, this graduate-level and professional reference addresses the relationship between fracture mechanisms (macroscale) and the microscopic, with the goal of explaining macroscopic fracture behavior based on a microscopic fracture mechanism. A careful fusion of mechanics and materials science, this text and monograph systematically considers an array of materials, from metals through ceramics and polymers, and demonstrates lab-tested strategies to develop desirable high-temperature materials for technological applications.

This book discusses the mechanical properties of ceramics and aims to provide both a solid background for undergraduate students, as well as serving as a text to bring practicing engineers up to date with the latest developments in this topic so they can use and apply these to their actual engineering work. Generally, ceramics are made by moistening a mixture of clays, casting it into desired shapes and then firing it to a high temperature, a process known as 'vitrification'. The relatively late development of metallurgy was contingent on the availability of ceramics and the know-how to mold them into the appropriate forms. Because of the characteristics of ceramics, they offer great advantages over metals in specific applications in which hardness, wear resistance and chemical stability at high temperatures are essential. Clearly, modern ceramics manufacturing has come a long way from the early clay-processing fabrication method, and the last two decades have seen the development of sophisticated techniques to produce a large variety of ceramic material. The chapters of this volume are ordered to help students with their laboratory experiments and guide their observations in parallel with lectures based on the current text. Thus, the first chapter is devoted to mechanical testing. A chapter of ductile and superplastic ceramic is added to emphasize their role in modern ceramics (chapter 2). These are followed by the theoretical basis of the subject. Various aspects of the mechanical properties are discussed in the following chapters, among them, strengthening mechanisms, time dependent and cyclic deformation of ceramics. Many practical illustrations are provided representing various observations encountered in actual ceramic-structures of particularly technical significance. A comprehensive list of references at the end of each chapter is included in this textbook to provide a broad basis for further studying the subject. The work also contains a unique chapter on a topic not discussed in other textbooks on ceramics concerning nanosized ceramics. This work will also be useful as a reference for materials scientists, not only to those who specialize in ceramics.

A balanced mechanics-materials approach and coverage of the latest developments in biomaterials and electronic materials, the new edition of this popular text is the most thorough and modern book available for upper-level undergraduate courses on the mechanical behavior of materials. To ensure that the student gains a thorough understanding the authors present the fundamental mechanisms that operate at micro- and nano-meter level across a wide-range of materials, in a way that is mathematically simple and requires no extensive knowledge of materials. This integrated approach provides a conceptual presentation that shows how the microstructure of a material controls its mechanical behavior, and this is reinforced through extensive use of micrographs and illustrations. New worked examples and exercises help the student test their understanding. Further resources for this title, including lecture slides of select illustrations and solutions for exercises, are available online at www.cambridge.org/97800521866758.

The Army Materials and Mechanics Research Center has conducted the Sagamore Army Materials Research Conferences, in cooperation with the Metallurgical Research Laboratories of the Department of Chemical Engineering and Metallurgy of Syracuse University, since 1954. The purpose of the conferences has been to gather together scientists and engineers from academic institutions, industry, and government who are uniquely qualified to explore in depth a subject of importance to the Army, the Department of Defense and the scientific corr.munity. This volume, Surfaces and Interfaces ll: Physical and Mechanical Properties, can be considered a continuation, or perhaps an extension, of the information contained in Surfaces and Interfaces I: Chemical and Physical Characteristics. The emphasis in this volume is focused on: the technological significance of surfaces and interfaces; surface sensitive mechanical properties; environment-sensitive properties; control of grain structure; and composite materials. It is felt that the rather ambitious undertaking of the program committee to place the role of "surfaces and interfaces" in its proper context has been achieved. The balance between basic research findings and more applied research allows the reader a certain degree of latitude in the use of the two volumes. The continued active interest and support of these conferences by Col. C. T. Riordan, Commanding Officer, Dr. E. Scala, Technical Di rector, and J. F. Sullivan, Deputy Technical Director, of the Army Materials and Mechanics Research Center is appreciated.

Updated to reflect recent developments in our understanding of deformation and fracture processes in structural materials. This completely revised reference includes new sections on isostress analysis, modulus of rupture, creep fracture micromechanicsms, and many more.