Analysis of a Crack Bridged by a Single Fiber

1992 ◽  
Vol 59 (3) ◽  
pp. 524-529 ◽  
Author(s):  
G. Meda ◽  
P. S. Steif
Keyword(s):  
Approximate Method ◽  
Singular Integral Equations ◽  
Single Fiber ◽  
Solution Technique ◽  
Matrix Interface ◽  
Matrix Cracks ◽  
Fiber Matrix Interface ◽  
Edge Dislocations ◽  
Crack Faces ◽  
Frictional Slip

With the goal of assessing the accuracy of a widely used approximate method of analyzing bridged matrix cracks, an idealized problem representing a crack bridged by a single fiber is studied in detail. Our solution technique, which accounts for frictional slip at the fiber-matrix interface explicitly, involves the use of distributions of edge dislocations to represent the opening of the crack faces and the slip at the interface. Through this method, the solution is reduced to a set of three coupled singular integral equations which are solved numerically. The results are compared with those from the approximate method, and some sources of discrepancy between the two results are explored.

Damping in Unidirectional and Cross-Ply Ceramic Matrix Composites With Matrix Cracks

2001 ◽  
Author(s):  
Victor Birman ◽  
Larry W. Byrd
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Interfacial Friction ◽  
Matrix Composites ◽  
Matrix Interface ◽  
Unidirectional Composites ◽  
Matrix Cracks ◽  
Dissipation Of Energy ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Abstract The paper elucidates the methods of estimating damping in ceramic matrix composites (CMC) with matrix cracks. Unidirectional composites with bridging matrix cracks and cross-ply laminates with tunneling cracks in transverse layers and bridging cracks in longitudinal layers are considered. It is shown that bridging matrix cracks may dramatically increase damping in unidirectional CMC due to a dissipation of energy along damaged sections of the fiber-matrix interface (interfacial friction). Such friction is absent in the case of tunneling cracks in transverse layers of cross-ply laminates where the changes in damping due to a degradation of the stiffness remain small. However, damping in cross-ply laminates abruptly increases if bridging cracks appear in the longitudinal layers.

Environmental Effects on Interface Behavior in Graphite / Epoxy Single Fiber Composites

1995 ◽  
Vol 385 ◽  
Author(s):  
Linda S. Schadler ◽  
Michael J. Koczak ◽  
Maher S. Amer
Keyword(s):  
Degradation Mechanism ◽  
Interfacial Shear Stress ◽  
Fiber Composites ◽  
Interfacial Shear ◽  
Single Fiber ◽  
Graphite Fiber ◽  
Matrix Interface ◽  
Micro Raman Spectroscopy ◽  
Stress Profiles ◽  
Fiber Matrix Interface

ABSTRACTToray M40 graphite fiber / Epon 828 epoxy resin single fiber composites with both sized and unsized fibers were exposed to distilled water at 50°C and 100°C, 10% NaOH and HCl aqueous solutions at 50°C, and air at 100°C. Micro Raman spectroscopy was used to measure the strain and interfacial shear stress profiles as a function of environmental exposure. It was found that the degradation mechanism is primarily a mechanical failure of the fiber/matrix interface.

scholarly journals Finite Element Modeling of the Fiber-Matrix Interface in Polymer Composites

2020 ◽  
Vol 4 (2) ◽  
pp. 58 ◽  
Author(s):  
Daljeet K. Singh ◽  
Amol Vaidya ◽  
Vinoy Thomas ◽  
Merlin Theodore ◽  
Surbhi Kore ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Polymer Composites ◽  
Parametric Study ◽  
Single Fiber ◽  
Interface Debonding ◽  
Matrix Interface ◽  
The Matrix ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Polymer composites are used in numerous industries due to their high specific strength and high specific stiffness. Composites have markedly different properties than both the reinforcement and the matrix. Of the several factors that govern the final properties of the composite, the interface is an important factor that influences the stress transfer between the fiber and matrix. The present study is an effort to characterize and model the fiber-matrix interface in polymer matrix composites. Finite element models were developed to study the interfacial behavior during pull-out of a single fiber in continuous fiber-reinforced polymer composites. A three-dimensional (3D) unit-cell cohesive damage model (CDM) for the fiber/matrix interface debonding was employed to investigate the effect of interface/sizing coverage on the fiber. Furthermore, a two-dimensional (2D) axisymmetric model was used to (a) analyze the sensitivity of interface stiffness, interface strength, friction coefficient, and fiber length via a parametric study; and (b) study the shear stress distribution across the fiber-interface-matrix zone. It was determined that the force required to debond a single fiber from the matrix is three times higher if there is adequate distribution of the sizing on the fiber. The parametric study indicated that cohesive strength was the most influential factor in debonding. Moreover, the stress distribution model showed the debonding mechanism of the interface. It was observed that the interface debonded first from the matrix and remained in contact with the fiber even when the fiber was completely pulled out.

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