Subcritical crack growth mechanisms in ceramic matrix composites: experimental observations and modelling

2001 ◽  
Vol 16 (1/2/3) ◽  
pp. 132
Author(s):  
Charles A. Lewinsohn ◽  
Charles H Henager Jr ◽  
Charles F. Windisch ◽  
Edward P. Simonen ◽  
Russell H. Jones ◽  
...  
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Growth Mechanisms

Development of ASTM Test Standards for the Mode I Interlaminar Fracture Toughness (GIc--Crack Growth Resistance) of Ceramic Matrix Composites

2018 ◽  
Author(s):  
Frank Abdi ◽  
Jalees Ahmad ◽  
Saber DorMohammadi ◽  
Cody Godines ◽  
Stephen Gonczy ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Crack Growth ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Crack Growth Resistance ◽  
Test Method ◽  
Mode I ◽  
Matrix Composites ◽  
Interlaminar Fracture

Ceramic matrix composite (CMC) materials are targeted for high temperature application in aircraft and power turbines, because of their low density and high-temperature thermo-mechanical properties, compared to conventional nickel super alloys. New test methods are needed for the assessment of the effects of delamination cracks on the structural integrity and life of CMC components. The ASTM C28 Fracture Toughness (Crack Growth Resistance – CGR) Working Group has drafted a standard test method for the “Mode I Interlaminar Fracture Tougness (GIc – Crack Growth Resistance) of Fiber-Reinforced Ceramic Matrix Composites (CMC) by Wedge Loading of a Double Cantilever Beam at Ambient Temperatures” The wedge loading method was developed to avoid the problems of high temperature bonding of loading blocks and hinges. The ASTM test standard details the scope, use, and application of the test method, interferences, test equipment, specimen geometry and preparation, test procedures, data interpretation and calculation, and reporting requirements for the new CMC CGR test method.

scholarly journals Time Dependent Crack Initiation and Growth in Ceramic Matrix Composites

1997 ◽  
Author(s):  
Matthew R. Begley ◽  
Brian N. Cox ◽  
Robert M. McMeeking
Keyword(s):  
Crack Growth ◽  
Crack Tip ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Cracking ◽  
Time Dependent ◽  
Small Scale ◽  
Matrix Composites ◽  
Fine Grained ◽  
Growth Initiation

Matrix cracking in ceramic matrix composites with fine grained fibers at high temperatures will be governed by fiber creep, as relaxation of the fibers eliminates crack tip shielding. Using a time dependent bridging law which describes the effect of creeping fibers bridging a crack in an elastic matrix, crack growth initiation and history have been modeled. For a stationary crack, crack tip stress intensity factors as a function of time are presented to predict incubation times before subcritical crack growth. Two crack growth studies are reviewed: a constant velocity approximation for small-scale bridging, and a complete velocity history analysis which can be used to predict crack length as a function of time. The predictions are summarized and discussed in terms of identifying various regimes of crack growth initiation, subcritical growth, and catastrophic matrix cracking.

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