Toughening Mechanisms in Quasi-Brittle Materials

Toughening Mechanisms in Quasi-Brittle Materials
Title Toughening Mechanisms in Quasi-Brittle Materials PDF eBook
Author S.P. Shah
Publisher Springer Science & Business Media
Total Pages 590
Release 2012-12-06
Genre Science
ISBN 9401133883

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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.

Toughening Mechanisms in Quasi-Brittle Materials

Toughening Mechanisms in Quasi-Brittle Materials
Title Toughening Mechanisms in Quasi-Brittle Materials PDF eBook
Author S P Shah
Publisher
Total Pages 628
Release 1991-04-30
Genre
ISBN 9789401133890

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Toughening Mechanisms in Quasi-brittle Materials

Toughening Mechanisms in Quasi-brittle Materials
Title Toughening Mechanisms in Quasi-brittle Materials PDF eBook
Author Surendra P. Shah
Publisher
Total Pages 590
Release 1990
Genre
ISBN

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Toughening Mechanisms in Quasi-brittle Materials, July 16-20, 1990 ... Evanston, Illinois

Toughening Mechanisms in Quasi-brittle Materials, July 16-20, 1990 ... Evanston, Illinois
Title Toughening Mechanisms in Quasi-brittle Materials, July 16-20, 1990 ... Evanston, Illinois PDF eBook
Author
Publisher
Total Pages 589
Release 1990
Genre
ISBN

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Workshop Proceedings: Toughening Mechanisms in Quasi-Brittle Materials Held on 16-20 July 1990 in Evanston, Illinois

Workshop Proceedings: Toughening Mechanisms in Quasi-Brittle Materials Held on 16-20 July 1990 in Evanston, Illinois
Title Workshop Proceedings: Toughening Mechanisms in Quasi-Brittle Materials Held on 16-20 July 1990 in Evanston, Illinois PDF eBook
Author
Publisher
Total Pages 590
Release 1991
Genre
ISBN

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Recently, considerable interest has been developing in understanding and modeling the fracture processes in these quasi-brittle materials as well as in designing materials with improved toughness. The research activities in these groups of materials: ceramics, cement and rock can be substantially enhanced with the exchange of information between these three groups of investigators. Since the field is relatively new, it is likely that the researchers working with one set of materials are not aware of similar developments with other set of materials. Although each material has its own set of specific characteristics, many common aspects can be shared among these quasi-brittle materials. These include: (1) application of nonlinear fracture mechanics, (2) experimental and theoretical considerations of strain localization, (3) microscopic observation of fracture process zone, (4) nondestructive evaluation of damage, (5) models to relate microstructure with macroscopic response, and (6) development of experimental and theoretical tools. The purpose of this workshop was to bring together researchers addressing the problem of fracture in cement, ceramics, and rock so that they can share their knowledge and develop a more general syntheses of the problem.

NATO Advanced Research Workshop. Toughening Mechanisms in Quasi-Brittle Materials, Held in Evanston, Illinois on July 16-20, 1990

NATO Advanced Research Workshop. Toughening Mechanisms in Quasi-Brittle Materials, Held in Evanston, Illinois on July 16-20, 1990
Title NATO Advanced Research Workshop. Toughening Mechanisms in Quasi-Brittle Materials, Held in Evanston, Illinois on July 16-20, 1990 PDF eBook
Author Surendra P. Shah
Publisher
Total Pages 624
Release 1990
Genre
ISBN

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This workshop brought together researchers addressing the problem of fracture in cement, ceramics, and rock so that they could share their knowledge and develop a more general syntheses of the problem. This preprint volume contains contributions from lectures for each of the 9 sessions. The final proceedings of this workshop will be published in a hardcover book by Kluewer Academic Publishers (NATO ASI Series). This book will contain 36 chapters; the finalized contributions of 27 lectures and 9 reporters. Keywords: Quasi brittle materials, Toughening mechanisms in materials, Workshop, Cement fracture, Ceramic fracture, Rock fracture. (js).

Crack Deflection Toughening Mechanism in Brittle Materials

Crack Deflection Toughening Mechanism in Brittle Materials
Title Crack Deflection Toughening Mechanism in Brittle Materials PDF eBook
Author T. Ohashi
Publisher
Total Pages 15
Release 2002
Genre Brittleness
ISBN

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Toughening mechanisms in polycrystalline ceramics and ceramic-based composites were discussed based on Griffith's energy equilibrium and classified into three groups: (A) the frontal process-zone toughening mechanism, (B) the crack-bridging mechanism, and (C) the macroscopic crack-deflection mechanism. The increase in fracture toughness caused by enforced macroscopic crack-deflection was estimated using the energy equilibrium between the energy-release rate and the fracture-energy rate. The analytical results revealed that the fracture toughness under Mode I loading was enhanced by twice the normal value when the crack propagates in the direction 90° from its original plane. Under Mode II loading the fracture toughness is increased 1.2 times the normal value when the crack propagates in its original plane. Crack-deflection tests were carried out by using wooden, thin rectangular plates with a central crack. The increase in the fracture toughness caused by crack deflection was confirmed and the experimental data was coincident with the calculated results.