Download or read book Compressive Strength and Damage Mechanisms in Ceramic Materials I The Role of Subcritical Tensile Microfracture Processes in Compression Failure of Ceramics II Electron Channeling Study of Fracture in Alumina Evidence for Crack Tip Plasticity written by James Lankford and published by . This book was released on 1981 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: The compressive strength of SiC, Si3N4, and Al2O3 is investigated over wide ranges in temperature and loading rate. Several distinct damage regimes are identified, all based upon tensile microfracture processes. Two aspects of the work are of special interest. The first is the identification of a high strain rate regime in which material inertial effects are responsible for unusually rapid strengthening; the basis for the effect is increased difficulty in either crack nucleation or extension. Secondly, it is found that at low loading rates, subcritical tensile microcrack growth is responsible for a thermally activated strength dependence. Selected area electron channeling experiments lead to the conclusion that the thermal activation process may involve crack tip plasticity. (Author).
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1982 with total page 1282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1982 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Compressive Strength and Damage Mechanisms in Ceramic Materials I Temperature Strain Rate Dependence of Compressive Strength and Damage Mechanism in Aluminum Oxide II Threshold Microfracture During Elastic Plastic Indentation of Ceramics written by James Lankford and published by . This book was released on 1980 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of compression tests of Al2O3 performed over a wide range in temperature and strain rate are interpreted in terms of dominant damage mechanisms. It is shown that compressive failure in Al2O3 is caused by one of three different mechanisms, each based on tensile (Mode I) growth of predominantly axial microcracks, and each characteristic of a specific temperature-strain rate regime. The concepts developed should be applicable to other strong ceramics. In addition, indentation experiments were carried out for a variety of ceramics. It is found that the threshold for microfracture during elastic-plastic indentation corresponds to radial, rather than subsurface median, crack formation. This is contrary to the fundamental assumption of existing models for threshold crack nucleation by sharp indenters or particles; the results indicate the need to modify the stress field calculations used in these models. (Author).
Download or read book Compressive Strength Hardness and Identification Damage in Ceramic Materials written by James Lankford (Jr) and published by . This book was released on 1982 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hardness and compressive strength of several strong ceramics are measured from room temperature to 1000 C. Similarities in behavior, and the results of microscopic examination, are interpreted in terms of the relative contributions of microplasticity and microfracture to material failure during compression testing and microhardness indentation. It is shown that microplasticity alone is an insufficient basis upon which to relate material response under the two test conditions, and that tensile microfracture is a significant contributor both to compressive failure and to subsurface indentation deformation, hence to hardness. Previous determinations of the strengths of several ceramics subject to impulsive loads were interpreted in terms of a theory based on material inertia. Recent experiments are described, which show that the dynamic strengthening mechanism is athermal, as required by the inertial theory, and that microcrack growth, rather than initiation, is suppressed by the inertial effect. Indentation microfracture measurements in the low load, near threshold regime were carried out using scanning electron microscopy. Results were interpreted in terms of existing theoretical treatments.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1982-03 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Toughening Mechanisms in Quasi Brittle Materials written by S.P. Shah and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: A variety of ceramic materials has been recently shown to exhibit nonlinear stress strain behavior. These materials include transformation-toughened zirconia which undergoes a stress-induced crystallographic transformation in the vicinity of a propagating crack, microcracking ceramics, and ceramic-fiber reinforced ceramic matrices. Since many of these materials are under consideration for structural applications, understanding fracture in these quasi-brittle materials is essential. Portland cement concrete is a relatively brittle material. As a result mechanical behavior of concrete, conventionally reinforced concrete, prestressed concrete and fiber reinforced concrete is critically influenced by crack propagation. Crack propagation in concrete is characterized by a fracture process zone, microcracking, and aggregate bridging. Such phenomena give concrete toughening mechanisms, and as a result, the macroscopic response of concrete can be characterized as that of a quasi-brittle material. To design super high performance cement composites, it is essential to understand the complex fracture processes in concrete. A wide range of concern in design involves fracture in rock masses and rock structures. For example, prediction of the extension or initiation of fracture is important in: 1) the design of caverns (such as underground nuclear waste isolation) subjected to earthquake shaking or explosions, 2) the production of geothermal and petroleum energy, and 3) predicting and monitoring earthquakes. Depending upon the grain size and mineralogical composition, rock may also exhibit characteristics of quasi-brittle materials.
Download or read book Fracture Mechanics of Ceramics written by Richard Carl Bradt and published by Springer Science & Business Media. This book was released on 1983-08-31 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fracture Mechanics of Ceramics written by R. C. Bradt and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: These volumes, 7 and 8, of Fracture Mechanics of Ceramics constitute the proceedings of an international symposium on the fracture mechanics of ceramic materials held at Virginia Polytechnic Institute and State University, Blacksburg, Virginia on June 19, 20 and 21, 1985. These proceedings constitute the fourth pair of volumes of a continuing series of conferences. The theme of this conference, as the previous three, focused on the mechanical behavior of ceramic materials in terms of the characteristics of cracks, particularly the roles which they assume in the fracture process. The 78 contributed papers by over 100 authors and co-authors represent the current state of the field. They address many of the theoretical and practical problems of interest to those concerned with brittle fracture. The program chairmen gratefully acknowledge the financial assistance for the Symposium provided by the EXXON Foundation, the Army Research Office, the Natio~al Science Foundation, and the Office of Naval Research. Without their support, this conference simply would not have been possible. The suggestions of Drs. J. C. Hurt, R. C. Pohanka, and L. Toth were particularly helpful in assuring the success of this symposium. Special appreciation is extended to Professor J. I. Robertson, C. P. Miles Professor of History. whose presentation following the banquet on the American Civil War was very well received by the audience. Finally, we wish to also thank our joint secretaries, especially Karen Snider, for their patience and help in finally bringing these proceedings to press.
Download or read book Fracture Mechanics of Ceramics written by R. C. Bradt and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: These volumes, 7 and 8, of Fracture Mechanics of Ceramics constitute the proceedings of an international symposium on the fracture mechanics of ceramic materials held at Virginia Polytechnic Institute and State University, Blacksburg, Virginia on June 19, 20 and 21, 1985. These proceedings constitute the fourth pair of volumes of a continuing series of conferences. The theme of this conference, as the previous three, focused on the mechanical behavior of ceramic materials in terms of the characteristics of cracks, particularly the roles which they assume in the fracture process. The 78 contributed papers by over 100 authors and co-authors represent the current state of the field. They address many of the theoretical and practical problems of interest to those concerned with brittle fracture. The program chairmen gratefully acknowledge the financial assistance for the Symposium provided by the EXXON Foundation, the Army Research Office, the National Science Foundation, and the Office of Naval Research. Without their support, this conference simply would not have been possible. The suggestions of Drs. J. C. Hurt, R. C. Pohanka, and L. Toth were particularly helpful in assuring the" success of this symposium. Special appreciation is extended to Professor J. I. Robertson, C. P. Miles Professor of History, whose presentation following the banquet on the American Civil War was very well received by the audience. Finally, we wish to also thank our joint secretaries, especially Karen Snider, for their patience and help in finally bringing these proceedings to press.
Download or read book Fracture Mechanics of Ceramics written by R.C. Bradt and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt: Second part of the proceedings of the Sixth International Symposium held in Karlsruhe, Germany, July 18-20, 1995.
Download or read book Fracture Mechanics of Ceramics written by R. C. Bradt and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: These volumes constitute the Proceedings of a Symposium ort the Fracture Mechanics of Cerarnics, held at the Pennsylvania State University, University Park, Pennsylvania, July 11, 12, and 13, 1973. The theme of the symposium focussed on the mechanical behavior of brittle cerarnics in terms of the characteristics of cracks. The 52 contributed papers by 87 authors, present an overview of the cur rent understanding of the theory and application of fracture mechan ics to brittle cerarnics. The prograrn chairmen gratefully acknowledge the financial assistance for the Symposium provided by the Office of Naval Re search, the College of Earth and Mineral Sciences of the Pennsyl vania State University, the Materials Research Center of Lehigh University, Bethlehem, Pennsylvana and Westinghouse Research Laboratories, Pittsburgh, Pennsylvania. Special appreciation is extended to the expert organization provided by the J. Orvis Keller Conference Center of the Pennsyl vania State Conference Center of the Pennsylvania State University. In particular, Mrs. Patricia Ewing should be acknowledged for the excellent prograrn organization and planning. Dean Harold J. O'Brien, who was featured as the after-dinner speaker and who presented a most stimulating talk on the cornrnunication between people, also contrib uted to the success of the meeting. Finally, we also wish to thank our joint secretaries for the patience and help in bringing these Proceedings to press. University Park R. C. Bradt Bethlehem D. P. H. Hasseiman Pittsburgh, Pennsylvania F. F. Lange July, 1973 v CONTENTS OF VOLUME 2 Contents of Volume 1 . . . . . . . . . . . . . . . . . . .
Download or read book Fracture in Ceramic Materials written by A. G. Evans and published by William Andrew. This book was released on 1984 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fracture Mechanics of Ceramics written by R.C. Bradt and published by Springer Science & Business Media. This book was released on 2013-03-07 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: These volumes, 9 and 10, of Fracture Mechanics of Ceramics constitute the proceedings of an international symposium on the fracture mechanics of ceramic materials held at the Japan Fine Ceramics Center, Nagoya, Japan on July 15, 16, 17, 1991. These proceedings constitute the fifth pair of volumes of a continuing series of conferences. Volumes 1 and 2 were from the 1973 symposium, volumes 3 and 4 from a 1977 symposium, and volumes 5 and 6 from a 1981 symposium all of which were held at The Pennsylvania State University. Volumes 7 and 8 are from the 1985 symposium which was held at the Virginia Polytechnic Institute and State University. The theme ofthis conference, as for the previous four, focused on the mechanical behavior ofceramic materials in terms of the characteristics ofcracks, particularly the roles which they assume in the fracture processes and mechanisms. The 82 contributed papers by over 150 authors and co-authors represent the current state of that field. They address many of the theoretical and practical problems ofinterest to those scientists and engineers concerned with brittle fracture.
Download or read book Fracture Mechanics of Ceramics written by R.C. Bradt and published by Springer Science & Business Media. This book was released on 2002-02-28 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume constitutes the proceedings of the 7th International Symposium on the Fracture Mechanics of Ceramics, held at the Presidium of the Russian Academy of Sciences, Moscow, Russia, on July 20-22, 1999. The theme of the symposium focused on the mechanical behavior of advanced ceramics in terms of the cracks, particularly the crack-microstructure interaction, delayed failure, and environmental effects in fracture. Special attention was paid to the novel methods in fracture mechanics testing, pre-standardization and standardization. Authors from 19 countries represented the current state of the field.
Download or read book Compressive Strength and Damage Mechanisms in Ceramic Materials written by James Lankford and published by . This book was released on 1980 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compressive strength measurements as a function of temperature and loading rate, and microhardness measurements as a function of temperature, have been carried out for Al2O3, SiC, and Si3N4. Results are correlated in terms of current theories connecting compressive strength, hardness, fracture toughness, and indentation microfracture. It is found that while high loading rates can suppress high temperature intergranular compressive fracture in SiC, this is not true in Al2O3. The threshold crack size for indentation microfracture as a function of temperature seems to correlate at least as well (if not better) with compressive strength as with hardness, and temperature-controlled compressive fracture mechanisms seem to operate during indentation fracture at corresponding temperatures. (Author).
Download or read book Fracture Mechanics of Ceramics written by R.C. Bradt and published by Springer Science & Business Media. This book was released on 2010-01-11 with total page 621 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 8th International Symposium on fracture mechanics of ceramics was held in on the campus of the University of Houston, Houston, TX, USA, on February 25-28, 2003. With the natural maturing of the fields of structural ceramics, this symposium focused on nano-scale materials, composites, thin films and coatings as well as glass. The symposium also addressed new issues on fundamentals of fracture mechanics and contact mechanics, and a session on reliability and standardization.
