Tunneling Cracks in Constrained Layers

1993 ◽  
Vol 60 (4) ◽  
pp. 890-894 ◽  
Author(s):  
S. Ho ◽  
Z. Suo
Keyword(s):  
Shear Fracture ◽  
Three Dimensional ◽  
Product Layer ◽  
Matrix Composites ◽  
Thermal Expansion Mismatch ◽  
Strain Fields ◽  
Brittle Matrix Composites ◽  
Brittle Layer ◽  
Applied Stresses ◽  
Reaction Product Layer

A thin, brittle layer bonded between tougher substrates is susceptible to cracking under residual and applied stresses. Such a crack initiates from an equi-axed flaw, confined by the substrates, tunneling in the brittle layer. Although tunneling is a three-dimensional process, the energy release rate at the front of a steady-state tunnel can be computed using plane strain fields. Several technically important problems are analyzed, including tunnels in adhesive joints, shear fracture, and kinked tunnels in a reaction product layer. The concept is finally applied to microcracking in brittle matrix composites caused by thermal expansion mismatch.

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.

Microcracks in Carbon/Carbon Composites: A Microtomography Investigation using Synchrotron Radiation

2001 ◽  
Vol 678 ◽  
Author(s):  
Oskar Paris ◽  
Herwig Peterlik ◽  
Dieter Loidl ◽  
Christoph Rau ◽  
Timm Weitkamp
Keyword(s):  
Mechanical Properties ◽  
Synchrotron Radiation ◽  
Phase Contrast ◽  
Three Dimensional ◽  
Carbon Composites ◽  
Matrix Composites ◽  
Crack Network ◽  
Brittle Matrix Composites ◽  
3D Information

AbstractThe mechanical properties of brittle matrix composites such as carbon/carbon (C/C) are closely related to the generation and propagation of microcracks. A better understanding of the role of microcracking requires a quantification of the three-dimensional morphology of the crack network. In this study we demonstrate that phase contrast microtomography using synchrotron radiation is a unique tool to get 3D information about cracks in C/C. This is shown for three different C/C specimens subjected to different final heat treatment temperatures (HTT). The results are discussed qualitatively with respect to the influence of HTT on the distribution of microcracks and their relevance for the mechanical properties of C/C.

Brittle Matrix Composites 8

2006 ◽  
Author(s):  
A.M. Brandt ◽  
V.C. Li ◽  
I.H. Marshall
Keyword(s):  
Matrix Composites ◽  
Brittle Matrix ◽  
Brittle Matrix Composites

Brittle matrix composites 7

2003 ◽  
Author(s):  
A. M. Brandt ◽  
V. C. Li ◽  
I. H. Marshall
Keyword(s):  
Matrix Composites ◽  
Brittle Matrix ◽  
Brittle Matrix Composites

Failure Modes in Brittle Matrix Composites (BMC).

1998 ◽  
Author(s):  
Nicholas J. Pagano ◽  
G. P. Tandon ◽  
R. Y. Kim
Keyword(s):  
Failure Modes ◽  
Matrix Composites ◽  
Brittle Matrix ◽  
Brittle Matrix Composites

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.

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