### Abstract

The sintered SiC fiber reinforced SiO _{2}-mullite composites with matrix compositions, i.e., SiO _{2}-3.7, 30, and 50 mol%Al _{2}O _{3}, had already been developed. In these composites, the thermal residual stress field changed with an increase in the coefficient of thermal expansion of the matrix accompanied by an increasing Al _{2}O _{3} content (mullite volume fraction) in the matrices. A three-point flexural test was conducted for the composites at room temperature. The strain gauge method and AE monitoring were used to detect the matrix cracking strain during the test. The effect of the thermal residual stress on the matrix cracking strain and fracture behavior were investigated. The results are as follows. The matrix cracking strain observed in the composites with a higher tensile thermal residual stress in the matrix region parallel to the fiber axis was well predicted by the BHE theory. For the SiC fiber/SiO _{2}-50 mol%Al _{2}O _{3} composite, the first acoustic emission signal was detected just after the initial proportional limit of the stress-strain curve. For the other composites, the signals were detected below this limit. When the residual stress in the matrix region parallel to the fiber axis was compressive, the linear fracture behavior was found. On the contrary, the bi-linear fracture behavior was enhanced by the tensile residual stress in the matrix. This tendency agreed with the prediction method by Luh and Evans. The magnitude of the fracture energy obtained in each composite was qualitatively explained by the conventional theoretical formula.

Original language | English |
---|---|

Pages (from-to) | 172-180 |

Number of pages | 9 |

Journal | Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals |

Volume | 68 |

Issue number | 2 |

Publication status | Published - 2004 Feb |

Externally published | Yes |

### Fingerprint

### Keywords

- Acoustic emission (AE)
- Ceramic matrix composite (CMC)
- Fracture behavior
- Matrix cracking
- Thermal residual stress

### ASJC Scopus subject areas

- Metals and Alloys

### Cite this

_{2}-Mullite Composites.

*Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals*,

*68*(2), 172-180.

**Effect of Thermal Residual Stress on Matrix Cracking Strain and Fracture Behavior of the Sintered SiC Fiber Reinforced SiO _{2}-Mullite Composites.** / Nagahisa, Kenya; Iwamoto, Kazuteru; Shinozaki, Kenji; Sasaki, Gen; Enoki, Manabu; Yoshida, Makoto.

Research output: Contribution to journal › Article

_{2}-Mullite Composites',

*Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals*, vol. 68, no. 2, pp. 172-180.

_{2}-Mullite Composites. Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals. 2004 Feb;68(2):172-180.

}

TY - JOUR

T1 - Effect of Thermal Residual Stress on Matrix Cracking Strain and Fracture Behavior of the Sintered SiC Fiber Reinforced SiO 2-Mullite Composites

AU - Nagahisa, Kenya

AU - Iwamoto, Kazuteru

AU - Shinozaki, Kenji

AU - Sasaki, Gen

AU - Enoki, Manabu

AU - Yoshida, Makoto

PY - 2004/2

Y1 - 2004/2

N2 - The sintered SiC fiber reinforced SiO 2-mullite composites with matrix compositions, i.e., SiO 2-3.7, 30, and 50 mol%Al 2O 3, had already been developed. In these composites, the thermal residual stress field changed with an increase in the coefficient of thermal expansion of the matrix accompanied by an increasing Al 2O 3 content (mullite volume fraction) in the matrices. A three-point flexural test was conducted for the composites at room temperature. The strain gauge method and AE monitoring were used to detect the matrix cracking strain during the test. The effect of the thermal residual stress on the matrix cracking strain and fracture behavior were investigated. The results are as follows. The matrix cracking strain observed in the composites with a higher tensile thermal residual stress in the matrix region parallel to the fiber axis was well predicted by the BHE theory. For the SiC fiber/SiO 2-50 mol%Al 2O 3 composite, the first acoustic emission signal was detected just after the initial proportional limit of the stress-strain curve. For the other composites, the signals were detected below this limit. When the residual stress in the matrix region parallel to the fiber axis was compressive, the linear fracture behavior was found. On the contrary, the bi-linear fracture behavior was enhanced by the tensile residual stress in the matrix. This tendency agreed with the prediction method by Luh and Evans. The magnitude of the fracture energy obtained in each composite was qualitatively explained by the conventional theoretical formula.

AB - The sintered SiC fiber reinforced SiO 2-mullite composites with matrix compositions, i.e., SiO 2-3.7, 30, and 50 mol%Al 2O 3, had already been developed. In these composites, the thermal residual stress field changed with an increase in the coefficient of thermal expansion of the matrix accompanied by an increasing Al 2O 3 content (mullite volume fraction) in the matrices. A three-point flexural test was conducted for the composites at room temperature. The strain gauge method and AE monitoring were used to detect the matrix cracking strain during the test. The effect of the thermal residual stress on the matrix cracking strain and fracture behavior were investigated. The results are as follows. The matrix cracking strain observed in the composites with a higher tensile thermal residual stress in the matrix region parallel to the fiber axis was well predicted by the BHE theory. For the SiC fiber/SiO 2-50 mol%Al 2O 3 composite, the first acoustic emission signal was detected just after the initial proportional limit of the stress-strain curve. For the other composites, the signals were detected below this limit. When the residual stress in the matrix region parallel to the fiber axis was compressive, the linear fracture behavior was found. On the contrary, the bi-linear fracture behavior was enhanced by the tensile residual stress in the matrix. This tendency agreed with the prediction method by Luh and Evans. The magnitude of the fracture energy obtained in each composite was qualitatively explained by the conventional theoretical formula.

KW - Acoustic emission (AE)

KW - Ceramic matrix composite (CMC)

KW - Fracture behavior

KW - Matrix cracking

KW - Thermal residual stress

UR - http://www.scopus.com/inward/record.url?scp=1942508184&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=1942508184&partnerID=8YFLogxK

M3 - Article

VL - 68

SP - 172

EP - 180

JO - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals

JF - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals

SN - 0021-4876

IS - 2

ER -