Role of interface properties on the toughness of brittle matrix composites reinforced with ductile fibers

1992 ◽  
Vol 7 (11) ◽  
pp. 3132-3138 ◽  
Author(s):  
H.E. Dève ◽  
S. Schmauder
Keyword(s):  
Fracture Resistance ◽  
Crack Opening ◽  
Geometrical Model ◽  
Interface Properties ◽  
Matrix Composites ◽  
Brittle Matrix Composites ◽  
The Matrix ◽  
Interface Sliding ◽  
Brittle Composites

The incorporation of ductile fibers in brittle matrices can lead to a significant increase in fracture resistance. The increase in toughness that derives from crack bridging is governed by the properties of the matrix/fiber interface and the ductility of the fibers. The current study addresses the role of interface sliding stress on the toughness of brittle composites reinforced with ductile fibers. The debond length is explicitly related to the interface sliding stress and the properties of the fiber. It is then incorporated into a geometrical model to simulate the bridging tractions versus crack opening under condition of continuous debonding. The implications on the effect of interfaces on the resistance curve are discussed.

Stochastic Aspects of Matrix Cracking in Brittle Matrix Composites

1993 ◽  
Vol 115 (3) ◽  
pp. 314-318 ◽  
Author(s):  
S. M. Spearing ◽  
F. W. Zok
Keyword(s):  
Matrix Cracking ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Tensile Response ◽  
Brittle Matrix Composites ◽  
Crack Interactions ◽  
The Matrix ◽  
Interface Slip ◽  
Bridging Fibers

A computer simulation of multiple cracking in fiber-reinforced brittle matrix composites has been conducted, with emphasis on the role of the matrix flaw distribution. The simulations incorporate the effect of bridging fibers on the stress required for cracking. Both short and long (steady-state) flaws are considered. Furthermore, the effects of crack interactions (through the overlap of interface slip lengths) are incorporated. The influence of the crack distribution on the tensile response of such composites is also examined.

Interfacial phenomena in the fracture resistance of interfaces

1988 ◽  
Vol 46 ◽  
pp. 720-721
Author(s):  
A. G. Evans
Keyword(s):  
Fracture Resistance ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Friction Stress ◽  
Matrix Composites ◽  
Low Friction ◽  
Fiber Failure ◽  
Pull Out ◽  
Brittle Matrix Composites ◽  
The Matrix

In composite systems, the mechanical response of interfaces to the approach of cracks that initially form either in the matrix or in the fiber dominates the mechanical performance. In particular, in brittle matrix composites, the interface must have a sufficiently low fracture resistance compared with that of both the fiber and matrix that the crack diverts into the interface and debonds the fiber, Thereafter, the debonded fiber must be able to slide against the matrix with a low friction stress in order to inhibit fiber failure and thus enhance pull-out. These processes are schematically illustrated in Fig. 1. Mechanics investigations have established requirements concerning debonding and sliding that must be satisfied in order to achieve good composite properties. At the simplest level, these studies reveal that the fracture energy of the interface should be less than about one-third that of either the fiber or the matrix.

Matrix cracking and the mechanical behaviour of SiC─CAS composites

1992 ◽  
Vol 437 (1899) ◽  
pp. 109-131 ◽  
Keyword(s):  
Elastic Properties ◽  
Three Dimensional ◽  
Matrix Cracking ◽  
Repeated Loading ◽  
Matrix Composites ◽  
Pull Out ◽  
Matrix Cracks ◽  
Brittle Matrix Composites ◽  
Dimensional Network ◽  
The Matrix

An experimental investigation has been carried out on the mechanical properties of unidirectional (0) 12 , (0, 90) 3S , (±45, 0 2 ) S , and (±45) 3S composites consisting of CAS glass ceramic reinforced with Nicalon SiC fibres. Measurements have been made of the elastic properties and of the tensile, compression and shear strengths of the composites, and these have been supported by a detailed study of the damage which occurs during monotonic and repeated loading. These damage studies have been carried out by means of edge replication microscopy and acoustic emission monitoring. The elastic properties of the composites are, by and large, close to the values that would be predicted from the constituent properties and lay-up sequences, but their strengths are lower than expected, and it appears that the Nicalon reinforcing fibre has been seriously degraded during manufacture. The fracture energy is much higher than predicted from observations of fibre pull-out, and it is suggested that the energy required to form a close three-dimensional network of matrix cracks could account for the high apparent toughness. The matrix cracking stress can be predicted reasonably closely by the Aveston, Cooper and Kelly model of cracking in brittle matrix composites, but it is shown that subcritical microcracks can form and/or grow at stresses well below the predicted critical values without affecting composite properties.

Stability Analysis of Bridged Cracks in Brittle Matrix Composites

1993 ◽  
Vol 115 (1) ◽  
pp. 127-138 ◽  
Author(s):  
R. Ballarini ◽  
S. Muju
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Opening ◽  
Matrix Crack ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Matrix Cracks ◽  
Brittle Matrix Composites ◽  
Propagating Crack

The bridging of matrix cracks by fibers is an important toughening mechanism in fiber-reinforced brittle matrix composites. This paper presents the results of a nonlinear finite element analysis of the Mode I propagation of a bridged matrix crack in a finite size specimen. The composite is modeled as an orthotropic continuum and the bridging due to the fibers is modeled as a distribution of tractions that resist crack opening. A critical stress intensity factor criterion is employed for matrix crack propagation, while a critical crack opening condition is used for fiber failure. The structural response of the specimen (load-deflection curves) as well as the stress intensity factor of the propagating crack is calculated for various constituent properties and specimen configurations for both tensile and bending loading. By controlling the length of the bridged crack, results are obtained that highlight the transition from stable to unstable behavior of the propagating crack.

Stability Analysis of Bridged Cracks in Brittle Matrix Composites

1991 ◽  
Author(s):  
Roberto Ballarini ◽  
Sandeep Muju
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Opening ◽  
Matrix Crack ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Matrix Cracks ◽  
Brittle Matrix Composites ◽  
Propagating Crack

The bridging of matrix cracks by fibers is an important toughening mechanism in fiber reinforced brittle matrix composites. This paper presents the results of a non-linear finite element analysis of the Mode-I propagation of a bridged matrix crack in a finite size specimen. The composite is modeled as an orthotropic continuum and the bridging due to the fibers is modeled as a distribution of tractions which resist crack opening. A critical stress intensity factor criterion is employed for matrix crack propagation while a critical crack opening condition is used for fiber failure. The structural response of the specimen (load-deflection curves) as well as the stress intensity factor of the propagating crack are calculated for various constituent properties and specimen configurations for both tensile and bending loading. By controlling the length of the bridged crack results are obtained which highlight the transition from stable to unstable behavior of the propagating crack.

Microstructure and Damping Capacity of AlNp/Mg-Al Composites with Different Particle Contents

2017 ◽  
Vol 898 ◽  
pp. 933-943 ◽  
Author(s):  
Yong Wang ◽  
Kai Ming Cheng ◽  
Ji Xue Zhou ◽  
Yuan Sheng Yang
Keyword(s):  
Internal Friction ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Damping Capacity ◽  
Matrix Composites ◽  
Internal Friction Peak ◽  
Experimental Frequency ◽  
The Matrix ◽  
Temperature Ranges ◽  
Interface Sliding

The AlN particles reinforced magnesium-aluminum matrix composites were fabricated by powder metallurgy and the damping mechanism was discussed. The results showed that the best damping capacity of composite reached with the addition of 6wt% AlN reinforcement, while the AlN particles were uniformly dispersed in the matrix. The damping capacity of composites decreases with the increasing of the reinforcement content and the experimental frequency. The internal friction peak related to dislocation appearance in the temperature ranges of 100-150°C. In addition, another internal friction peak of composites between 200 and 250°C arose, which was related to interface sliding.

Experimental Investigation of Interface Properties in SiC Fiberreinforced Reaction-Bonded Silicon Nitride Matrix Composites

1994 ◽  
Vol 365 ◽  
Author(s):  
J.I. Eldridge ◽  
R.T. Bhatt
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Ceramic Matrix Composites ◽  
Interfacial Properties ◽  
Interface Properties ◽  
Matrix Composites ◽  
Fiber Volume ◽  
The Matrix ◽  
Push Out ◽  
Spacing Method

ABSTRACTInterfacial properties of 1-D SiC/RBSN composites were measured by the matrix crack spacing method and by the fiber push-out method, and the results were compared. The composites consisted of 8 to 33 vol% of aligned SCS-6 SiC fibers (142 μm diameter) in a relatively porous (20 to 40 vol%) Si3N4 matrix. The effects of fiber volume fraction and test temperature on the interfacial properties have been investigated. The advantages and limitations of both methods in evaluating the interface properties of fiber-reinforced ceramic matrix composites and the factors influencing the interfacial measurements are discussed.

Effect of Fiber Extensibility on the Fracture Toughness of Short Fiber or Brittle Matrix Composites

1992 ◽  
Vol 45 (8) ◽  
pp. 377-389 ◽  
Author(s):  
L. K. Jain ◽  
R. C. Wetherhold
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Fiber Orientation ◽  
Crack Opening ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Pull Out ◽  
General Terms ◽  
Brittle Matrix Composites ◽  
Fiber Orientation Distribution

A micromechanical model based on probabilistic principles is proposed to determine the effective fracture toughness increment and the bridging stress-crack opening displacement relationship for brittle matrix composites reinforced with short, poorly bonded fibers. Emphasis is placed on studying the effect of fiber extensibility on the bridging stress and the bridging fracture energy, and to determine its importance in cementitious matrix composites. Since the fibers may not be in an ideal aligned or random state, the analysis is placed in sufficiently general terms to consider any prescribable fiber orientation distribution. The model incorporates the snubbing effect observed during pull-out of fibers inclined at an angle to the crack face normal. In addition, the model allows the fibers to break; any fiber whose load meets or exceeds a single-valued failure stress will fracture rather than pull out. The crack bridging results may be expressed as the sum of results for inextensible fibers and an additional term due to fiber extensibility. An exact analysis is given which gives the steady-state bridging toughness G directly, but presents a non-linear problem for the bridging stress-crack opening (σb – δ) relationship. An approximate analysis is then presented which gives both G and σb – δ directly. To illustrate the effect of extensibility on bridging stress and fracture energy increment due to bridging fibers, a comparison with the inextensible fiber case is provided. It is found that effect of extensibility on fracture energy is negligible for common materials systems. However, extensibility may have a significant effect on the bridging stress-crack opening relationship. The effect of other physical and material parameters such as fiber length, fiber orientation and snubbing friction coefficient is also studied.

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