scholarly journals Criteria For Progressive Interfacial Debonding With Friction In Fiber-Reinforced Ceramic Composites

1995 ◽  
Vol 409 ◽  
Author(s):  
Chun-Hway Hsueh
Keyword(s):  
Axial Strain ◽  
Crack Opening ◽  
Ceramic Composites ◽  
Interfacial Debonding ◽  
Fiber Reinforced ◽  
Opening Displacement ◽  
Strain Criterion ◽  
Mismatch Strain ◽  
The Matrix ◽  
Debonded Interface

AbstractCriteria for progressive debonding at the fiber/matrix interface with friction along the debonded interface are considered for fiber-reinforced ceramic composites. The energy-based criterion is adopted to analyze the debond length, the crack-opening displacement, and the displacement of the composite due to interfacial debonding. The analytical solutions are identical to those obtained from the mismatch-strain criterion, in which interfacial debonding is assumed to occur when the mismatch in the axial strain between the fiber and the matrix reaches a critical value. Furthermore, the mismatch-strain criterion is found to bear the same physical meaning as the strength-based criterion.

scholarly journals Non-Steady First Matrix Cracking of Fiber-Reinforced Ceramics

2020 ◽  
Author(s):  
Huan Wang
Keyword(s):  
Steady State ◽  
Crack Opening ◽  
Ceramic Matrix Composites ◽  
Matrix Cracking ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Opening Displacement ◽  
Interface Shear ◽  
The Matrix ◽  
Lag Model

Matrix cracking affects the reliability and safety of fiber-reinforced ceramic-matrix composites during operation. The matrix cracking can be divided into two types, that is, steady state crack and non-steady state cracking. This chapter is about the non-steady stable cracking of fiber-reinforced CMCs. The micro stress field of fiber, matrix, and interface shear stress along the fiber direction is analyzed using the shear-lag model. The relationship between the crack opening displacement and the crack surface closure traction is derived. The experimental first matrix cracking stress of different CMCs are predicted.

Metal-Reinforced Ceramic Composites for Turbine Vanes

1972 ◽  
Author(s):  
S. A. Bortz
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Metal Fiber ◽  
Turbine Engine ◽  
Turbine Vanes ◽  
The Matrix ◽  
The Relationship ◽  
Structural Matrix

Experiments have been performed which indicate the potential of metal-fiber reinforced-ceramic matrix composites for use as a high temperature structural matrix. The results of this work reveal that metal-fiber reinforced ceramics obey compostie theory, and that after cracks occur in the matrix, a pseudo-ductility can be introduced into the composite. This toughness can be predicted from equations of work required to pull the fibers through the matrix. The relationship between strength, toughness, and crack depths, are dependent on the inter-facial bond between the fibers and matrix as well as fiber diameter and length. Based on the results of these experiments, multicomponent materials with superior resistance to failure from oxidation, thermal shock, and high mechanical stresses in air above 2400 F can be postulated. These materials have potential for use as gas turbine engine vanes.

scholarly journals Effect of Thickness on Fatigue Crack Propagation in Injection Molded Short Carbon Fiber Reinforced Plastics

2018 ◽  
Vol 165 ◽  
pp. 07002 ◽  
Author(s):  
Kenichi Shimizu ◽  
Yuya Hasegawa ◽  
Keisuke Tanaka
Keyword(s):  
Carbon Fiber ◽  
Crack Propagation ◽  
Crack Opening Displacement ◽  
Crack Opening ◽  
Plate Thickness ◽  
Fiber Reinforced ◽  
Opening Displacement ◽  
Short Carbon Fiber ◽  
Carbon Fiber Reinforced ◽  
Short Carbon

The influence of plate thickness on the fatigue crack propagation behavior was studied by using center-notched specimens which were cut from injection-molded plates of short carbon-fiber reinforced polyphenylene sulfide (PPS) at two fiber angles relative to the molding flow direction (MFD), i. e. θ=0 deg. (MD), 90 deg. (TD). The short carbon-fiber reinforced plastics (SCFRP) plates have three-layer structure where the fiber orientation is parallel to MFD in the shell layer and is nearly perpendicular in the core layer. The fraction of the core layer increases with increase in the plate thickness. In the relation between the crack propagation rate, da/dN, and stress intensity factor, ΔK, da/dN increases with increase in thickness for MD specimen. Conversely, da/dN decreases for TD specimen. The crack opening displacement along the crack was measured by using the digital image correlation (DIC) method. The measured crack opening displacement become larger with increase in the plate thickness for MD specimens. Contrary, measured values become smaller with increase in the plate thickness for TD specimen. The crack-tip-opening radius, Δρ, was estimated from the parabolic approximation of the crack opening displacement distribution near the crack tip. The relationships between da/dN and Δρ for all specimens tend to merge into a unique relationship.

In-Situ NDE Monitoring of Crack Bridging in Ceramic Composites via Crack Opening Displacement

1994 ◽  
Author(s):  
Abhisak Chulya ◽  
John P. Gyekenyesi
Keyword(s):  
Crack Opening ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
In Situ Observation ◽  
Matrix Composites ◽  
Opening Displacement ◽  
Crack Bridging ◽  
Interferometric Technique ◽  
Fiber Bridging

A study of crack bridging in long-fiber reinforced ceramic matrix composites (CMC) is the main focus of this paper. The in-situ observation using NDE techniques reveals that 1D SiC/CAS CMCs show only partial fiber bridging behavior while 2D SiC/SiC CMCs possess an excellent bridging mechanism. Laser interferometric technique was successfully applied to measure crack opening displacements (COD) in the notched specimens under four-point flexural loading. The onset of precracking and the effects of fiber bridging were also detected by in-situ optical microscopy and acoustic emission techniques. The applied load-COD relations were shown and on the basis of these results, the bridging stiffness parameter can be determined via the fracture mechanics formulation proposed by Cox and Marshall.

Anisotropic Media with a Crack or a Rigid Line Inclusion,

1996 ◽  
Author(s):  
T. T. C. Ting
Keyword(s):  
Crack Opening Displacement ◽  
Crack Opening ◽  
Null Vector ◽  
Opening Displacement ◽  
Rigid Line Inclusion ◽  
Rigid Line ◽  
The Matrix ◽  
Structural Failures ◽  
The Right ◽  
Line Inclusion

A crack, or cracks, in a material is perhaps one of the most studied problems in solid mechanics. This is due to the fact that many structural failures are related to the presence of a crack in the material. The knowledge of stress distribution near a crack tip is indispensable in a fracture mechanics analysis (Rice, 1968; Sih and Liebowitz, 1968; Sih and Chen, 1981; Kanninen and Popelar, 1985; K. C. Wu, 1989a). A crack is represented by a slit cut whose surfaces are assumed traction-free. This is a mathematical idealization. For a composite material that consists of stiff short fibers or whiskers in the matrix, we have rigid line inclusions. A rigid line inclusion is the counterpart of a crack. It is sometimes called an anticrack. The displacement at a rigid line inclusion either vanishes or has a rigid body translation and rotation. One of the puzzling problems for a crack is the one when it is located on the x1-axis that is an interface between two dissimilar materials. The displacement of the crack surfaces near the crack tips may oscillate, creating a physically unacceptable phenomenon of interpenetration of two materials. The bimaterial tensor Š introduced in Section 8.8 plays a key role in the analysis. If Š vanishes identically, there is no oscillation. If Š is nonzero, we may decompose the tractions applied on the crack surfaces into two components, one along the right null vector of Š denoted by to and the other on the right eigenplane of Š denoted by tγ . The solution associated with to is not oscillatory. It has the property that the traction on the interface x2=0 is polarized along the right null vector of Š while the crack opening displacement is polarized along the left null vector of Š. The solution associated with tγ is oscillatory. It has the property that the traction on the interface x2=0 is polarized on the right eigenplane of Š while the crack opening displacement is polarized on the left eigenplane of Š.

Matrix Cracking In Brittle-Matrix Composites with Tailored Interfaces

1994 ◽  
Vol 365 ◽  
Author(s):  
Sawai Danchaivijit ◽  
L-Y. Chao ◽  
D. K. Shetfty
Keyword(s):  
Steady State ◽  
Crack Length ◽  
Uniaxial Tension ◽  
Sliding Friction ◽  
Crack Opening ◽  
State Theory ◽  
Matrix Cracking ◽  
Opening Displacement ◽  
The Matrix ◽  
Cracking Stress

ABSTRACTMatrix cracking from controlled through cracks with bridging filaments was studied in a model unidirectional composite of SiC filaments in an epoxy-bonded alumina matrix. An unbonded, frictional interface was produced by moderating the curing shrinkage of the epoxy with the alumina filler and coating the filaments with a releasing agent. Uniaxial tension test specimens (2.5 × 25 × 125 mm) with filament-bridged through cracks were fabricated by a novel two-step casting technique involving casting, precracking and joining of cracked and uncracked sections. Distinct matrix-cracking stresses, corresponding to the extension of the filamentbridged cracks, were measured in uniaxial tension tests using a high-sensitivity extensometer. The crack-length dependence of the matrix-cracking stress was found to be in good agreement with the prediction of a fracture-mechanics analysis that employed a new crack-closure force - crack-opening displacement relation in the calculation of the stress intensity for fiber-bridged cracks. The prediction was based on independent experimental measurements of the matrix fracture toughness (Kcm), the interfacial sliding friction stress (τ) and the residual stress in the matrix (σmI). The matrix-cracking stress for crack lengths (2a) greater than 3 mm was independent of the crack length and agreed with the prediction of the steady-state theory of Budiansky, Hutchinson and Evans[2]. Tests on specimens without the deliberately introduced cracks indicated a matrix-cracking stress significantly higher than the steady-state stress.

Fiber Pullout Characteristics Under Dynamic Loading Conditions

2001 ◽  
Author(s):  
N. Sridhar ◽  
Q. D. Yang ◽  
B. N. Cox
Keyword(s):  
Shear Stress ◽  
Crack Opening ◽  
Interfacial Shear Stress ◽  
Friction Stress ◽  
Crack Plane ◽  
Opening Displacement ◽  
Fiber Pullout ◽  
Dynamic Propagation ◽  
Dependent Relationship ◽  
The Matrix

Abstract Inertial effects in the mechanism of fiber pullout during dynamic propagation of a bridged crack are critically examined. By reposing simple shear lag models of pullout as problems of dynamic wave propagation, the effect of frictional coupling between the fiber and the matrix is accounted for in a fairly straightforward way. The frictional sliding between the fiber and the matrix is described by a constant interfacial friction stress, the sign of which depends on the relative particle velocity of the fiber and the matrix. Analytical solutions are derived when the load or bridging traction on the fiber in the crack plane increases linearly in time. The results show that when the wave speed of the matrix exceeds a critical value, the frictional fiber pullout behavior transitions from a state of pure slip to a state where part of the sliding zone slips and the remaining sticks. When stick occurs, the fiber and the matrix within the stick zone slide past each other with an interfacial shear stress less than the shear stress required for slipping. Regions of slip and stick propagate and increase with time and influence the time-dependent relationship between the crack opening displacement and the bridging tractions.

scholarly journals Fiber reinforced mortars based on free Portland-CSA binders under high stress rate

2018 ◽  
Vol 183 ◽  
pp. 04013 ◽  
Author(s):  
Luigi Coppola ◽  
Denny Coffetti ◽  
Elena Crotti ◽  
Daniele Forni ◽  
Ezio Cadoni
Keyword(s):  
Dynamic Behaviour ◽  
Crack Opening ◽  
High Stress ◽  
Hydrated Lime ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Fiber Reinforced ◽  
Opening Displacement ◽  
Split Hopkinson Tensile Bar ◽  
Split Hopkinson

In this paper, dynamic behaviour of fiber reinforced mortars manufactured with innovative binders based on calcium sulphoaluminate cement (CSA), supplementary cementitious materials (SCMs), gypsum (G) and hydrated lime (CH) was investigated. Fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used to develop sustainable Portland-free cementitious materials. Polypropylene structural fibers (1% by mortar volume) were used to reinforce the cementitious matrix. Fresh properties of mortars were evaluated in terms of workability and specific mass. In addition, elastic modulus, compressive and flexural strength were determined up 28 days from casting. The dynamic behaviour was studied by means of Split Hopkinson Tensile bar having 60 mm in diameter. Preliminary dynamic results reported in terms of stress versus crack opening displacement were evaluated and discussed.

The complexity of the matrix micro structure in SiC-fiber-reinforced glass ceramic composites

1995 ◽  
Vol 15 (12) ◽  
pp. 1235-1247 ◽  
Author(s):  
Franck Doreau ◽  
Hélène Maupas ◽  
Dominique Kervadec ◽  
Pierre Ruterana ◽  
Jean Vicens ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Ceramic Composites ◽  
Fiber Reinforced ◽  
Micro Structure ◽  
Sic Fiber ◽  
The Matrix
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