| On a Rational Analysis Methodology for 3-D Braided Fibrous Composites |
20 FEB 97 |
98 pages |
| Authors:
A. S. Wang; DREXEL UNIV PHILADELPHIA PA
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 | This final technical report summarizes the research results obtained under Air Force Office of Scientific Research Grant F-49620-94-O3lS, which covered the duration from 1 July 1994 to 30 September 1996. The main objective of this research is to develop a rational analysis approach which accomplishments the rapidly advancing technology in Textile Composite Materials. Key results rendered are grouped and discussed in seven categories: (1) Modeling yarn architecture in preforms; (2) ... |
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| A Comprehensive Study of Matrix Fracture Mechanisms in Fiber-Reinforced Ceramic Matrix Composites |
30 JUN 93 |
79 pages |
| Authors:
A. S. Wang; M. W. Barsoum; DREXEL UNIV PHILADELPHIA PA
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| This final technical report summarizes the activities, accomplishment and research results obtained under the research grant AFOSR-90-0712, which covered the period from 15 February 1990 to 30 April 1993. The main objective of the research is to study the physical mechanisms of matrix microcracking which constitutes the fundamental cause for the toughness and strength properties in fiber-reinforced ceramic-matrix composites. Major results summarized in this report include (1) fabrication of the ... |
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| MTS High Temperature Testing System |
30 JAN 90 |
5 pages |
| Authors:
A. S. Wang; M. Barsoum; DREXEL UNIV PHILADELPHIA PA
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| This report describes the MTS High Temperature Testing System which was funded by AFSOR under the DURIP Program and installed at Drexel University. This testing system is dedicated exclusively for basic studies on the micromechanics behaviors of fiber-reinforced ceramic matrix composites under extreme temperature conditions. Owing to its very high temperature capability and versatility to perform tests in several testing configurations, this equipment has casted a positive impact on current ... |
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| A Comprehensive Study on Microstructure Mechanics Relationships of Ceramic Matrix Composites |
20 DEC 89 |
29 pages |
| Authors:
A. S. Wang; M. W. Barsoum; DREXEL UNIV PHILADELPHIA PA
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| The background of this research stems from the need to understand the physical mechanisms of brittle matrix cracks in fiber reinforced ceramic matrix composites. Three major tasks are performed during the research: an in-house fabrication facility is established; a testing technique is developed; and a theory for matrix crack initiation and a numerical simulation method is formulated. A preliminary correlation between theory and experiment is accomplished. This report contains two ... |
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| Computation Equipment for Damage Simulation in Laminated Composites |
25 FEB 88 |
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| Authors:
A. S. Wang; DREXEL UNIV PHILADELPHIA PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS
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 | This report describes the MicroVAX II based computational equipment funded by the Air Force Office of Scientific Research and installed at Drexel University. This equipment is dedicated exclusively for computational mechanics for composites materials research. Owing to its large computing capacity and availability to perform intensive computational tasks at substantially lower unit cost, this equipment has casted positive impacts on current AFOSR programs and other research work conducted at Drexel ... |
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| A Comprehensive Study on Damage Tolerance Properties of Notched Composite Laminates |
FEB 88 |
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| Authors:
A. S. Wang; E. S. Reddy; W. Binienda; U. Zhong; DREXEL INST OF TECH PHILADELPHIA PA DEPT OF MECHANICAL ENGINEERING
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| This final report contains the results of an investigation on matrix- related damage mechanisms in notched composite laminates. The theoretical approach taken follows the principles of micromechanisms and the mechanics of brittle fracture at the descriptive level considered valid for the so-called ply-elasticity. Namely, the laminate is basically treated as a 3-dimensional elastic solid which is made of distinctly anisotropic layers. Brittle fracture can initiate and propagate within any layer ... |
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| Mixed-Mode Fracture of Uniaxial Fiber Reinforced Composites |
15 APR 87 |
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| Authors:
A. S. Wang; W. Binienda; E. S. Reddy; Y. Zhong; DREXEL UNIV PHILADELPHIA PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS
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| Mixed-mode matrix fracture in notched off-axis undirectional composite is investigated. First the problem is treated by an exact formulation based on elastic fracture mechanics. It is then simulated by a finite element model. Correlation with experiment suggests a fracture criterion based on total strain energy release rate as the fracture parameter. Keywords: Composite material, Graphite epoxy, Mixed mode fracture matrix cracking, Singular integral equation, Finite element simulation, Experiment analysis correlation. ... |
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| Fracture Analysis of Matrix Cracking in Laminated Composites |
JAN 85 |
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| Authors:
A. S. Wang; NATIONAL RESEARCH COUNCIL WASHINGTON DC
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| This report presents an analytical approach to describe the initiation and propagation behaviors of matrix-dominant cracks in laminated composites. A rational analysis method for the phenomenological characteristics of matrix cracking is developed on the basis of ply-elasticity, fracture mechanics and effective material flaw concepts. Emphasis is placed on the basic mechanisms of multiple random cracks formation, delamination growth and interactions among cracks of differing propagation modes. Examples simulating laboratoroy coupon ... |
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| Cumulative Damage Model for Advanced Composite Materials. |
23 FEB 1984 |
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| Authors:
A. S. Wang; R. B. Bucinell; DYNA EAST CORP PHILADELPHIA PA
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| The main objective was to apply a cumulative damage model to laminates with practical lamination geometries and thus predict the cumulative damage states for both static and fatigue loading. Preliminary damage analysis has shown that significant differences exist in the damage accumulation characteristics among the three laminate types tested. Both the laminates edge delamination onset load and their ultimate strengths display sufficient differences which are clearly distinguished in the results. ... |
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| Cumulative Damage Model for Advanced Composite Materials. |
23 FEB 1983 |
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| Authors:
P. C. Chou; A. S. Wang; DYNA EAST CORP WYNNEWOOD PA
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| Work progress is reported for research program to develop a cumulative damage model which can be used to relate the strength, stiffness and service life properties of epoxy based structural composites. The desired cumulative damage model takes into account the effect of load-history, character of the applied stress (tension, compression, etc.), lamination stacking sequence, the effect of natural and man-made flaws and the inherent mechanical properties of the basic composite ... |
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| On Mixed Mode Fracture in Off-Axis Unidirectional Graphite-Epoxy Composites, |
25 OCT 1982 |
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| Authors:
A. S. Wang; N. N. Kishore; W. W. Feng
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| The results of a fracture experiment in which matrix-dominant mixed-mode cracks are induced with controlled propagation direction and controlled values of mode-II to mode-I ratio are discussed. The test specimens used belong a class of off-axis, doubly side-notched unidirectional graphite/epoxy composite. By varying the off-axis angle from 0 degrees to 90 degrees, a wide range of mixed-mode cracking conditions are created under a simple uniaxial tension. From the test results ... |
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| A Theory for Transverse Cracks in Composite Lasminates, |
1982 |
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| Authors:
A. S. Wang; H. Miller; P. C. Chou; DYNA EAST CORP WYNNEWOOD PA
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| A theory is presented which brings together the basic concepts in fracture mechanics and the probabilistic nature of material properties. The results rendered by the theory is a distribution function with the applied load as the independent variable, which is then related to the transverse crack density. This theory was then correlated with experiments on various pi over 4 graphite/epoxy laminates. (Author, modified). |
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| Compressive Strength of a Unidirectional Graphite/Epoxy Composite Following a Tensile Proof-Load, |
1981 |
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| Authors:
J. M. Alper; A. S. Wang
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| Results are presented of a proof-test on unidirectional graphite/epoxy composites conducted to determine whether the assumption of equal rank between tensile and compressive strength is valid. If the compressive strength of the specimens is not altered by the tensile proof-load, then the minimum compressive strength of the specimens surviving the tensile proof-load can be determined statistically using the equal rank assumption. (Author, modified). |
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| Interlaminar Failure in Epoxy Based Composite Laminates, |
23 MAY 79 |
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| Authors:
A. S. Wang; F. W. Crossman; G. E. Law Jr.
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| A finite element method was used in conjunction with an energy principle of classical linear fracture mechanics in order to describe the various aspects of the delamination mechanisms of graphite fiber reinforced epoxy composite laminates. The results obtained were compared with experiments, and it was shown that the energy method predicts well free-edge delamination in laminates under uniaxial tension (including the initiation, the growth and the growth stability of the ... |
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| Cumulative Damage Model for Advanced Composite Materials. |
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| Authors:
P. C. Chou; A. S. Wang; H. Miller; DYNA EAST CORP WYNNEWOOD PA
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| A cumulative damage model for composite laminates was developed. The model defines the effects of load history, character of applied stresses, and ply properties on the effective laminate response (strength, modulus, and life) of an arbitrary symmetric composite laminate with known unidirectional properties. Four major damage modes were identified for composite laminates. Each of these damage modes was studied in detail and theories developed for laminate response under static loading. ... |
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| On Mixed-Mode Fracture in Off-Axis Unidirectional Graphite-Epoxy Composites, |
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| Authors:
A. S. Wang; N. N. Kishore; W. W. Feng; LAWRENCE LIVERMORE NATIONAL LAB LIVERMORE CA
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| The results of a fracture experiment, in which matrix-dominant mixed-mode cracks are induced with controlled propagation direction and controlled values of mode-II to mode-I ratio are discussed. The test specimens used belong to a class of off-axis, doubly side-notched unidirectional graphite/epoxy composite. By varying the off-axis angle from 0 degrees to 90 degress, a wide range of mixed-mode cracking conditions are created under a simple uniaxial tension. From the test ... |
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