Comparisons of interface shear stress degradation rate between C/SiC and SiC/SiC ceramic-matrix composites under cyclic fatigue loading at room and elevated temperatures

2016 ◽  
Vol 24 (2) ◽  
pp. 171-202 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Elevated Temperatures ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Cyclic Fatigue ◽  
Matrix Composites ◽  
Interface Shear ◽  
Interface Shear Stress ◽  
Sic Ceramic ◽  
Stress Degradation

scholarly journals Thermomechanical Characterization of SiC/SiC Ceramic Matrix Composites in a Combustion Facility

Ceramics ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 407-425 ◽  
Author(s):  
Ragav P. Panakarajupally ◽  
Michael J. Presby ◽  
K. Manigandan ◽  
Jianyu Zhou ◽  
George G. Chase ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Mechanical Loading ◽  
High Velocity ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Matrix Composites ◽  
Front Side ◽  
Sic Ceramic ◽  
Combustion Environment

A combustion facility which includes uniaxial mechanical loading was implemented that enables environmental conditions more akin to jet engine environments compared to conventional static environment tests. Two types of woven SiC/SiC ceramic matrix composites (CMCs), melt-infiltrated (MI) and chemical vapor infiltrated (CVI), were subjected to fatigue loading in the combustion facility and under isothermal furnace conditions. Some CVI test coupons were coated with a multilayer environmental barrier coating (EBC) of mullite + ytterbium monosilicate using slurry infiltration process to demonstrate the performance with a coating. Combustion conditions were applied using a high velocity oxy fuel gun on the front side of the specimen and mechanical loading was applied using a horizontal hydraulic MTS machine. All the specimens considered were subjected to tension-tension fatigue loading at 100 MPa, stress ratio of 0.1 and specimen front-side surface temperature of 1200 ± 20 °C. Nondestructive evaluation (NDE) methods, such as electrical resistance (ER), was used as an in-situ health monitoring technique. Similar fatigue tests were performed in an isothermal furnace for comparison. A much lower fatigue life was observed for the uncoated specimens tested under combustion conditions in comparison to isothermal furnace condition. This difference in fatigue life was attributed to damage associated with added thermal stress due to the thermal gradient and higher rate of oxidative embrittlement due to the presence of high velocity combustion gases in the combustion environment. EBC coating increased the fatigue life in combustion environment. However, EBC coated specimens experienced spallation in the high-velocity flame due to the presence of micro cracks in the coating surface. Fracture surfaces of the failed specimens were investigated under the scanning electron microscope (SEM) to determine the extent of oxidation and damage.

scholarly journals Effect of Cyclic Fatigue Loading on Matrix Multiple Fracture of Fiber-Reinforced Ceramic-Matrix Composites

Ceramics ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 327-346 ◽  
Author(s):  
Longbiao Li
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Cyclic Fatigue ◽  
Matrix Cracking ◽  
Matrix Composites ◽  
Matrix Interface ◽  
Multiple Fracture ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

In this paper, the effect of cyclic fatigue loading on matrix multiple fracture of fiber-reinforced ceramic-matrix composites (CMCs) is investigated using the critical matrix strain energy (CMSE) criterion. The relationships between multiple matrix cracking, cyclic fatigue peak stress, fiber/matrix interface wear, and debonding are established. The effects of fiber volume fraction, fiber/matrix interface shear stress, and applied cycle number on matrix multiple fracture and fiber/matrix interface debonding and interface wear are discussed. Comparisons of multiple matrix cracking with/without cyclic fatigue loading are analyzed. The experimental matrix cracking of unidirectional SiC/CAS, SiC/SiC, SiC/Borosilicate, and mini-SiC/SiC composites with/without cyclic fatigue loading are predicted.

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