Prediction of Lifetime in Static Fatigue at High Temperatures for Ceramic Matrix Composites

2010 ◽  
Vol 112 ◽  
pp. 129-140 ◽  
Author(s):  
O. Loseille ◽  
Jacques Lamon
Keyword(s):  
Crack Growth ◽  
High Temperatures ◽  
Slow Crack Growth ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Woven Composites ◽  
Static Fatigue ◽  
Matrix Composites ◽  
Random Load ◽  
Delayed Failure

Previous works have shown that ceramic matrix composites are sensitive to delayed failure during fatigue in oxidizing environments. The phenomenon of slow crack growth has been deeply investigated on single fibers and multifilament tows in previous papers. The present paper proposes a multiscale model of failure driven by slow crack growth in fibers, for 2D woven composites under a constant load. The model is based on the delayed failure of longitudinal tows. Additional phenomena involved in the failure of tows have been identified using fractographic examination of 2D woven SiC/SiC composite testspecimens after fatigue tests at high temperatures. Stochastic features including random load sharing, fiber overloading, fiber characteristics and fiber arrangement within the tows have been introduced using appropriate density functions. Rupture time predictions are compared to experimental data.

scholarly journals Fracture in Metallic Ribbon Reinforced Ceramic Matrix Composites

1992 ◽  
Vol 1 (3) ◽  
pp. 096369359200100
Author(s):  
Rajendra U Vaidya ◽  
K K Chawla ◽  
T K Lee ◽  
K N Subramanian
Keyword(s):  
Fracture Surface ◽  
Metallic Glass ◽  
Crack Growth ◽  
Glass Matrix ◽  
Slow Crack Growth ◽  
Amorphous Ribbon ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Glass Matrix Composite

The fracture surfaces of a metallic–glass (amorphous) ribbon reinforced glass–ceramic and metallic ribbon reinforced glass matrix composite were studied. The features observed in the fracture surface of the brittle matrix were interpreted in terms of fast and slow crack growth in these composites. The implications of the nature of this crack growth on the toughness of such composites was also investigated.

scholarly journals Rear Earth Oxide Multilayer Deposited by Plasma Spray-Physical Vapor Deposition for Envisaged Application as Thermal/Environmental Barrier Coating

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 889
Author(s):  
Jie Zhong ◽  
Dongling Yang ◽  
Shuangquan Guo ◽  
Xiaofeng Zhang ◽  
Xinghua Liang ◽  
...  
Keyword(s):  
Composite Coating ◽  
High Temperatures ◽  
Physical Vapor Deposition ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Environmental Barrier ◽  
Chemical Attack ◽  
Environmental Barrier Coating ◽  
Barrier Coating

SiC fiber-reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) are being increasingly used in the hot sections of gas turbines because of their light weight and mechanical properties at high temperatures. The objective of this investigation was the development of a thermal/environmental barrier coating (T/EBC) composite coating system consisting of an environmental barrier coating (EBC) to protect the ceramic matrix composites from chemical attack and a thermal barrier coating (TBC) that insulates and reduces the ceramic matrix composites substrate temperature for increased lifetime. In this paper, a plasma spray-physical vapor deposition (PS-PVD) method was used to prepare multilayer Si–HfO2/Yb2Si2O7/Yb2SiO5/Gd2Zr2O7 composite coatings on the surface of SiCf/SiC ceramic matrix composites. The purpose of this study is to develop a coating with resistance to high temperatures and chemical attack. Different process parameters are adopted, and their influence on the microstructure characteristics of the coating is discussed. The water quenching thermal cycle of the coating at high temperatures was tested. The results show that the structure of the thermal/environmental barrier composite coating changes after water quenching because point defects and dislocations appear in the Gd2Zr2O7 and Yb2SiO5 coatings. A phase transition was found to occur in the Yb2SiO5 and Yb2Si2O7 coatings. The failure mechanism of the T/EBC composite coating is mainly spalling when the top layer penetrates cracks and cracking occurs in the interface of the Si–HfO2/Yb2Si2O7 coating.

Multi-Axial Failure of Ceramic Matrix Composite Fiber Tows

2011 ◽  
Vol 78 (3) ◽  
Author(s):  
M. Blacklock ◽  
D. R. Hayhurst
Keyword(s):  
Axial Stress ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Composite Fiber ◽  
Woven Composites ◽  
Matrix Composites ◽  
Stress Strain ◽  
Fiber Failure ◽  
Stressed Region

This paper considers the multi-axial stress-strain-failure response of two commercially woven ceramic matrix composites. The different failure mechanisms of uni-axially stressed tows and woven composites are addressed. A model is postulated in which the local transverse and shear stressing, arising from the weave, instantaneously deactivate wake debonding and fiber pullout and initiates dynamic fiber failure; hence, triggering catastrophic failure of the axially stressed region of the tow. The model is shown to predict experimentally measured stress-strain-failure results for the woven composites considered. Simple stress-strain-failure models are also proposed for tows subjected to axial-transverse and axial-shear loadings, but due to the lack of experimental data they have not been validated.

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

Durability and Damage Development in Woven Ceramic Matrix Composites Under Tensile and Fatigue Loading at Room and Elevated Temperatures

2000 ◽  
Vol 122 (4) ◽  
pp. 394-401 ◽  
Author(s):  
A. Haque ◽  
M. Rahman
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Failure Strain ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Cracking ◽  
Woven Composites ◽  
Rate Equations ◽  
Matrix Composites ◽  
Damage Development

This paper investigates the damage development in SiC/SiNC woven composites under tensile and cyclic loading both at room and elevated temperatures. The ultimate strength, failure strain, proportional limit, and modulus data at a temperature range of 23°C–1250°C are generated. The tensile strength of SiC/SiNC woven composites has been observed to increase with increased temperatures up to 1000°C. The stress/strain plot shows a pseudo-yield point at 25 percent of the failure strain εf, which indicates damage initiation in the form of matrix cracking. The evolution of damage above 0.25 εf both at room and elevated temperature comprises of multiple matrix cracking, interfacial debonding, and fiber pullout. Although the nature of the stress/strain plot shows damage-tolerant behavior under static loading both at room and elevated temperature, the life expectancy of SiC/SiNC composites degrades significantly under cyclic loading at elevated temperature. This is mostly due to the interactions of fatigue damage caused by the mechanically induced plastic strain and the damage developed by the creep strain. The in-situ damage evolutions are monitored by acoustic event parameters, ultrasonic C-scan, and stiffness degradation. Rate equations for modulus degradation and fatigue life prediction of ceramic matrix composites both at room and elevated temperatures are developed. These rate equations are observed to show reasonable agreement with experimental results. [S0094-4289(00)02304-5]

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