| Oxide Coatings in Aero-Turbine Engines |
28 FEB 2008 |
3 pages |
| Authors:
Anthony G. Evans; John W. Hutchinson; CALIFORNIA UNIV SANTA BARBARA
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 | Oxide coatings used for various components in the hot section of aero-turbine engines experience temperature gradients at various stages during their flight cycle. One gradient exists during steady-state, due to the combination of the combustion environment next to the free surface and internal cooling of the underlying superalloy substrate. Other gradients develop during cooling of the surface when engine power is reduced. It is argued that deep delaminations, when observed ... |
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| Mechatronic Materials and Systems. Design and Demonstration of High Aughtority Shape Morphing Structures |
SEP 2005 |
226 pages |
| Authors:
Anthony G. Evans; S. L. dos Santos e Lucato; J. Wang; P. Maxwell; R. M. McMeeking; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
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| A concept for a high authority shape morphing plate is described and demonstrated. The design incorporates an active back-plane comprising a Kagome truss, capable of changing the shape of a solid face, connected to the back-plane by means of a tetrahedral truss core. The two shape deformations to be demonstrated consist of hinging and twisting. The design is performed by a combination of analytic estimation and numerical simulation, guided by ... |
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| Structrue and Deformation of Aluminum Foams Through Computed Tomography, |
1998 |
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| Authors:
David J. Sypeck; Haydu N. G. Wadley; Hilary Bart-Smith; Stephan Koehler; Anthony G. Evans
|
 | Highly porous metallic faoms by themselves or as the cores of ultralight metal structures have significant practical interest because of unique combinations of properties 1. |
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| HYSTERESIS LOOPS AND THE INELASTIC DEFORMATION OF 0/90 CERAMIC MATRIX COMPOSITES |
1996 |
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| Authors:
JEAN-MARC DOMERGUE; Fernando E. Heredia; Anthony G. Evans
|
| Hysteresis measurements obtained on 0/90 SiC/CAS and SiC/SiC have been used to analyze the interface responses. Four parameters have been derived from these measurements. These relate to the compliance change caused by matrix cracking, the frictional resistance of the interface, the interface debond resistance, and the residual stress. These parameters have been used to predict the stress/strain curves. Preliminary estimates of stress partitioning between the plies have been used to ... |
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| CONCEPT FOR A DAMAGE-TOLERANT CERAMIC COMPOSITE WITH "STRONG" INTERFACES |
1996 |
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| Authors:
WEN-CHIANG TU; Fred F. Lange; Anthony G. Evans
|
| A ceramic-matrix composite (CMC) that exhibits damage-tolerant behavior without "weak" interfaces has been demonstrated. The concept relies on the heterogeneous distribution of fiber bundles within a porous matrix having homogeneous, fine porosity. It also depends on the development of residual stress from thermal expansion mismatch. The present demonstration uses AL(2)O(3) fibers with either a silicon nitride or a mullite matrix. The latter is inherently oxidation resistant. |
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| MICROSTRUCTURE OF SILICON CARBIDE/CARBON COMPOSITES AND RELATIONSHIPS WITH MECHANICAL PROPERTIES |
25 AUG 1995 |
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| Authors:
XAVIER BOURRAT; KRISTOFER S. TURNER; Anthony G. Evans
|
| Three different 2-D SiC/C composites, analyzed by TEM, have mechanical performances directly controlled by the interfacial structure resulting from processing. Localized attachment of the fibers to a brittle matrix constituent is shown to be responsible for composite weakening by impeding interface debonding and sliding. Moreover, the particulate phase used in the matrix is found to have a strong influence. There is a consequent sensitivity of composite strength to the particulate ... |
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| RELATIONSHIPS BETWEEN HYSTERESIS MEASUREMENTS AND THE CONSTITUENT PROPERTIES OF CERAMIC MATRIX COMPOSITES: I, THEORY |
1995 |
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| Authors:
EMMANUEL VAGAGGINI; JEAN-MARC DOMERGUE; Anthony G. Evans
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| A methodology for assessing constituent properties of ceramic matrix composites (CMCs) from stress-strain curves is developed. The procedures demonstrate how the properties of the interface and the misfit strain can be related to the unload/reload hysteresis and the permanent strain. The approach is illustrated in companion papers by obtaining experimental measurements on two CMCs. The results demonstrate why differences in the sliding stress and the debond energy of the interfaces ... |
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| RELATIONSHIPS BETWEEN HYSTERESIS MEASUREMENTS AND THE CONSTITUENT PROPERTIES OF CERAMIC MATRIX COMPOSITES: II, EXPERIMENTAL STUDIES ON UNIDIRECTIONAL MATERIALS |
1995 |
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| Authors:
JEAN-MARC DOMERGUE; EMMANUEL VAGAGGINI; Anthony G. Evans
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| The use of hysteresis loop measurements for assessing the constituent properties of unidirectional CMCs is evaluated, using basic theory described in a companion paper. Results are obtained on SiC/CAS and SiC/SiC composites. These materials exhibit very different hysteresis characteristics, reflected in differences in sliding stress, Tau, and debond energy Gamma(i). These interface properties are manifest in the respective tensile stress/strain curves. |
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| TENSILE AND SHEAR PROPERTIES OF CONTINUOUS FIBER-REINFORCED SIC/AL(2)O(3) COMPOSITES PROCESSED BY MELT OXIDATION |
1995 |
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| Authors:
Fernando E. Heredia; Anthony G. Evans; Clarence A. Andersson
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| The mechanical properties of a fiber-reinforced SiC/Al(2)O(3) composite have been investigated in tension and shear. The material is shown to have class II characteristics (a "matrix dominated" ceramic matrix composite) with appreciable inelastic strain prior to failure. This strain is associated with matrix cracking accompanied by interface debonding and sliding. One consequence of this strain is the ability to redistribute stress, resulting in tensile notch insensitivity. Evaluation of the interface ... |
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| IN-PLANE MECHANICAL PROPERTIES OF SEVERAL CERAMIC-MATRIX COMPOSITES |
1995 |
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| Authors:
CARL CADY; Fernando E. Heredia; Anthony G. Evans
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| An attempt has been made to assess the generalized in-plane inelastic deformation and rupture properties of typical laminated or woven ceramic-matrix composites. The assessment is made by first identifying two principal classes of behavior. These classes are distinguished by the ratio of the elastic properties of the fibers to those of the matrix, which determines the mechanisms of deformation and rupture. These mechanisms, in turn, control the magnitude and orientation ... |
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| THE PROCESSING AND MECHANICAL PROPERTIES OF HIGH TEMPERATURE/HIGH PERFORMANCE COMPOSITES; BOOK 1 OF 7: MECHANISM-BASED CONSTITUTIVE LAWS AND DESIGN |
APR 1994 |
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| Authors:
Anthony G. Evans; FREDERIC A. LECKIE
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| THIS DOCUMENT DISCUSSES THE FOLLOWING: (1) MATERIALS SELECTION AND INNOVATION IN DESIGN; (2) ELASTO-PLASTIC ANALYSIS OF INTERFACE LAYERS FOR FIBER-REINFORCED METAL-MATRIX COMPOSITES; (3) MODELING OF ANISOTROPIC BEHAVIOR OF WEAKLY BONDED FIBER REINFORCED MMCS; (4) ON THE TENSILE PROPERTIES OF A FIBER REINFORCED TITANIUM MATRIX COMPOSITE; (5) CONTROL OF STRENGTH ANISOTROPY OF METAL MATRIX FIBER COMPOSITES; (6) INELASTIC STRAINS DUE TO MATRIX CRACKING IN UNIDIRECTIONAL FIBER-REINFORCED COMPOSITES; (7) LOCATION AND ULTIMATE ... |
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| MECHANISMS OF DEFORMATION AND FAILURE IN CARBON-MATRIX COMPOSITES SUBJECT TO TENSILE AND SHEAR LOADING |
28 FEB 1994 |
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| Authors:
KRISTOFER R. TURNER; JAMES S. SPECK; Anthony G. Evans
|
| The operative damage mechanisms in a series of C-matrix composites loaded in tension and shear have been investigated. The composites contained either C fibers or nicalon fibers, both with and without a carbon coating. The matrix consisted primarily of ex-phenolic carbon with a final carbon layer introduced by chemical vapor infiltration. Some composites have a high fiber/matrix sliding stress, Tau. In these composites, failure is characterized by localized fiber pullout. ... |
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| In-Plane Shear Properties of 2-D Ceramic Matrix Composites. |
1994 |
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| Authors:
Povl Brondsted; Fernando E. Heredia; Anthony G. Evans; RISOE NATIONAL LAB ROSKILDE (DENMARK)
|
| The in-plane shear properties of a range of 2-D ceramic matrix composites have been measured using the Iosipescu configuration. The nonlinear deformation is found to be associated primarily with matrix cracks. Consequently, the shear modulus decreases as strain proceeds. The flow strength in shear is found to be compatible with the stress at which multiple matrix cracking is expected to occur, without interface slip. Consequently, the shear strength scales with ... |
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| Stress Corrosion Cracking in a Unidirectional Ceramic-Matrix Composite. |
1994 |
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| Authors:
S. Mark Spearing; Frank W. Zok; Anthony G. Evans; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
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| A study of matrix cracking in a unidirectional ceramic-matrix composite under static loading conditions has been conducted. The evolution of crack density with time has been measured using both flexure and uniaxial tension tests. Subcritical cracking has been observed at stresses below that required to develop matrix cracks in short-duration, monotonic loading tests. Furthermore, a relatively high final crack density has been observed following extended periods (^10 to the 6th ... |
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| Notch Effects in Carbon Matrix Composites. |
1994 |
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| Authors:
Fernando E. Heredia; S. Mark Spearing; Thomas J. Mackin; Ming Y. He; Anthony G. Evans; CALIFORNIA UNIV SANTA BARBARA COLL OF ENGINEERING
|
| The tensile properties of various carbon matrix composites, reinforced with C and SiC fibers, have been evaluated. The objective is to assess mechanics procedures for characterizing the influence of holes and notches. Interpretation has been attempted using large-scale bridging mechanics, with linear elastic fracture mechanics as one limit and notch insensitivity as the other. Important differences between the materials, associated primarily with the fiber/matrix interfaces and the in-plane shear strength, ... |
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| Mechanically Induced Zone Darkening of Alumina/Ceria-Stabilized Zirconia Composites. |
1994 |
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| Authors:
Valter Sergo; Chiara Schmid; Sergio Meriani; Anthony G. Evans; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| Alumina/ceria-stabilized zirconia bars tested in four-point bending exhibited deformation bands on the tensile side due to localized tetragonal-to-monoclinic transformation. These bands became increasingly darker and were fully visible some weeks after the bending experiment. XPS spectra revealed that the darker regions are characterized by a higher concentration of cerium in the +3 oxidation state, as opposed to other undeformed regions, in which +4 is the predominant oxidation state. A numerical ... |
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| On Large Scale Sliding in Fiber-Reinforced Composites. |
1994 |
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| Authors:
Z. Cedric Xia; John W. Hutchinson; Anthony G. Evans; Bernard Budiansky; HARVARD UNIV CAMBRIDGE MA DIV OF APPLIED SCIENCES
|
| A critical examination is made of the use of the line-spring model to represent fiber bridging of matrix cracks in the analysis of failure phenomena in fiber-reinforced brittle matrix composites. attention is focused on composite systems designed to undergo fiber debonding and sliding when matrix cracking occurs. for most composites of this class, it is found that the distance along the fiber within which sliding occurs is often too large ... |
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| Mechanical Properties of Partially Dense Alumina Produced from Powder Compacts. |
1994 |
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| Authors:
David C. C. Lam; Fred F. Lange; Anthony G. Evans; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| The elastic modulus (E), the critical strain energy release rate (G(c)), and the flexural strength (sigma) have been determined for two partially dense alumina bodies produced from the same powder but with different relative densities. The measured elastic modulus, critical strain energy release rate, and a calculated critical stress intensity factor (K(c)) were observed to be linearly related to (rho-rho(o))/(1-rho(o)), where rho is the current relative density and rho(o) is ... |
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| THE PROCESSING AND MECHANICAL PROPERTIES OF HIGH TEMPERATURE/HIGH PERFORMANCE COMPOSITES. |
01 JAN 1993 |
|
| Authors:
Anthony G. Evans; Frederick A. Leckie
|
| University of California; Materials Department : Santa Barbara, California California |
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| THE PROCESSING AND MECHANICAL PROPERTIES OF HIGH TEMPERATURE/HIGH PERFORMANCE COMPOSITES. |
01 JAN 1993 |
|
| Authors:
Anthony G. Evans; Frederick A. Leckie
|
| University of California; Materials Department : Santa Barbara, California California |
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| THE PROCESSING AND MECHANICAL PROPERTIES OF HIGH TEMPERATURE/HIGH PERFORMANCE COMPOSITES. |
01 JAN 1993 |
|
| Authors:
Anthony G. Evans; Frederick A. Leckie
|
| University of California; Materials Department : Santa Barbara, California California |
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| Effect of Microstructure on the Strength and Fracture Energy of Bimaterial Interfaces. |
1993 |
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| Authors:
Anthony G. Evans; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| The annual report of the office of naval research grant at ucsb on strength and fracture energy of bimaterials interfaces includes three sections: mechanics of interfaces, coating design for composite systems, and mechanics of brittle matrix composites. for more details see executive summary. keywords:, composite materials, reports, bimaterials, coatings, fracture energy, interfacial mechanics, interfacial strength, article collections, assorted papers, bimaterial interfaces, interfacial, microstructures, onr. |
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| Effect of Microstructure on the Strength and Fracture Energy of Bimaterial Interfaces. |
1993 |
|
| Authors:
Anthony G. Evans; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| The annual report of the office of naval research grant at ucsb on strength and fracture energy of bimaterials. bimaterials interfaces includes three sections: mechanics of interface, coating design for, articles, composite materials, data, experimental, mmc, mmc data, reports, al2o3 fibers, bimaterials, fibers, nicalon fibers, scs-6 fibers, scs-6/ti, sic fibers, sic/ti-15-3, ti matrix, ti-15-3 matrix, cte data, debonding, fracture energy, interfacial crackings, interfacial fatigue, modulus data, poisson data, poisson's ratio, ... |
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| Kinking of a Crack Out of an Interface: Role of In-Plane Stress. |
1991 |
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| Authors:
Ming-Yuan He; Andrew Bartlett; Anthony G. Evans; John W. Hutchinson; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| A crack lying in the interface between two brittle elastic solids can advance either by continued growth in the interface of by kinking out of the interface into one of the adjoining materials. this competition can be assessed by comparing the ratio of the energy release rates for interface cracking and for kinking out of the interface to the ratio of interface toughness to substrate toughness. the stress parallel to ... |
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Reports by Author
