Notched strength of ceramic-matrix composites

Keith, William P.; Kedward, Keith T.

doi:10.1016/s0266-3538(97)00007-9

Cited by 15 publications

(18 citation statements)

References 7 publications

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“…In some cases, the increased notched strength above the notch insensitive solid line resulted due to notch strengthening effects. Similar results are also reported by Keith and Kedward 5 with double‐edge‐notched specimens. It needs to be noted that although the notched strength of cross‐ply specimens with a larger hole size a / w =0.4 falls above the net‐section notch‐insensitive solid line, the degree of notch insensitivity is observed to be comparatively less.…”

Section: Resultssupporting

confidence: 90%

“…It appears that Griffith's criterion represents better the notch‐insensitive behavior, while Suo's model predicts well the notch‐sensitive behavior of CMCs. Almost similar results have also been observed for double‐sided notched specimens by Keith and Kedward 5 …”

Section: Resultssupporting

confidence: 87%

“…Their study indicates that the strength of notched ceramic matrix composites depends on notch size, which is eventually governed by a dimensionless parameter consisting of hole radius, inelastic stretch due to frictional sliding, Young's modulus, and unnotched strength of composites. The experimental investigation of notched strength for silicon carbide fiber‐reinforced ceramic matrix composites has also been reported by some researchers, particularly for edge‐notched specimens 2,5 . Both notch sensitivity and insensitivity are reported in their work depending upon the notch size and interface conditions.…”

Section: Introductionmentioning

confidence: 67%

“…have described the transitional behavior between the ductile and brittle nature of fiber‐reinforced ceramic matrix composites. They have defined the composite strength ratio by the following equation: The geometric finite width parameter, F , in for central crack specimen can be approximated by 19 Keith and Kedward 5 have analyzed the notch sensitivity of edge‐notched ceramic matrix composites using both Griffith criterion and Suo's model through a dimensionless parameter, k . This dimensionless parameter, k , basically consists of toughness ( K IC ), unnotched strength, σ o , and specimen width, w .…”

Section: Stress Concentrations and Notch Sensitivitymentioning

confidence: 99%

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Stress Concentrations and Notch Sensitivity in Woven Ceramic Matrix Composites Containing a Circular Hole—An Experimental, Analytical, and Finite Element Study

Haque

Ahmed

Ramasetty

2005

Journal of the American Ceramic Society

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In this paper, the stress concentrations associated with a circular hole and subjected to uniform tensile loading in woven ceramic matrix composites (CMCs) have been determined experimentally through strain gauge measurements. The stress concentrations were calculated from the measured strain distributions surrounding the holes during the initial loading period. Then, the load‐carrying capacity of notched CMCs with various hole radius to width ratios (a/w) has been determined. The objective is to study the stress concentrations due to circular notch, and then evaluate the notch sensitivity in woven CMCs. Both quasi‐isotropic [0/90/+45/−45]s and cross‐ply [0/90/0/90]s laminates of woven SiC/SiNC composites were considered. The experimental data of stress concentrations were compared with the results obtained from a complex variable method and finite element analysis. The notched strength data were also analyzed on the basis of some existing theories. The results show significant stress concentrations in the range of 3.75–4.75 near the notch edges during the early stage of loading. But in most cases, the notched strength data show notch insensitivity in CMCs, particularly with small hole diameters. This occurs mostly due to stress redistribution effects during inelastic deformation in ceramic matrix composites. The degree of notch insensitivity in CMCs is observed to decrease with comparatively larger diameter holes. For notch insensitivity, the limiting value of a dimensionless parameter n, comprising of fracture toughness, un‐notched strength, and width of the specimen, has been determined on the basis of existing notch sensitivity theories. The stress concentration factors are seen not to be influenced by the lay‐up sequence of the laminate. Reasonable agreement was observed between the theory and experimentally determined stress concentration factors, particularly for small hole diameters.

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 67%

Section: Stress Concentrations and Notch Sensitivitymentioning

confidence: 99%

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Stress Concentrations and Notch Sensitivity in Woven Ceramic Matrix Composites Containing a Circular Hole—An Experimental, Analytical, and Finite Element Study

Haque

Ahmed

Ramasetty

2005

Journal of the American Ceramic Society

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“…As a consequence, the toughness of the composites decreases and the notch sensitivity increases. For crack extension driven by stress concentrations, the failure of CMCs can be related to the well-known Griffith criterion [42,43], which could explain the linear correlation:…”

Section: Discussionmentioning

confidence: 99%

Influence of heat treatment and fiber orientation on the damage threshold and the fracture behavior of Nextel fiber-reinforced Mullite-SiOC matrix composites analysed by acoustic emission monitoring

et al. 2014

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In the present study, we elucidate the influence of oxidative heat exposures at 1000 and 1200°C on an alumina fiber-reinforced polymer-derived ceramic matrix composite containing small residual amounts of carbon. Therefore, we investigated the flexural performance and fracture toughness of on-(0°/90°) and off-axis (45°) reinforced samples. Acoustic emission was used to monitor the internal damage and its progression during loading. At 1000°C, a moderate reduction of strength and fracture toughness is found while after exposure to 1200°C a dramatic decrease down to 50 % is observed. For all composites, a reduction of the damaged volume was found after heat treatments indicating a decrease of crack deflection. However, especially at 1000°C, composites reinforced in 0°/90°direction seemed to be more affected, as no detrimental effect on the mechanical performance was found for the 45°composites. Remarkably, the oxidation-induced silica formation increases the absolute and relative damage thresholds of all composites. A Griffithlike linear relationship between strength and toughness is found. These findings are pivotal for designing and engineering next generation CMCs toward long-term applications.

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Notch Sensitivity of Fatigue Behavior of a Hi-Nicalon™/SiC-B4C Composite at 1,200 °C in Air and in Steam

Ruggles‐Wrenn

Kurtz

2013

Appl Compos Mater

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Notched strength of ceramic-matrix composites

Cited by 15 publications

References 7 publications

Stress Concentrations and Notch Sensitivity in Woven Ceramic Matrix Composites Containing a Circular Hole—An Experimental, Analytical, and Finite Element Study

Stress Concentrations and Notch Sensitivity in Woven Ceramic Matrix Composites Containing a Circular Hole—An Experimental, Analytical, and Finite Element Study

Influence of heat treatment and fiber orientation on the damage threshold and the fracture behavior of Nextel fiber-reinforced Mullite-SiOC matrix composites analysed by acoustic emission monitoring

Notch Sensitivity of Fatigue Behavior of a Hi-Nicalon™/SiC-B4C Composite at 1,200 °C in Air and in Steam

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