Abstract
The influence of microstructure evolution on the dynamic mechanical properties, including storage modulus and internal friction, of the 2.5D SiCf/SiCm composites after high-temperature treatment (800 °C and 1400 °C) in the air was investigated by three-point bending vibration test. The effects of test frequency and amplitude on storage modulus and internal friction were also evaluated. The results show that as-prepared samples have maximum storage modulus and internal friction. However, the composites treated at 800 °C in the air have the minimum storage modulus due to a large number of defects produced within the composite structure, and the composites treated at 1400 °C have the minimum internal friction due to the formation of α-cristobalite in the interface between the matrix and fibers, resulting in stronger interface bonding. With regard to test conditions, the storage modulus is sensitive to amplitude but not frequency; however, the internal friction is sensitive to both frequency because of anelasticity and amplitude due to the static hysteresis.
Highlights
Mechanical Properties of 2.5DTurbine engines suffer severe dynamic loads caused by structural vibration and noise during service, and these vibrations should not exceed their resonance limit, so as not to damage the engine [1,2]
The dynamic mechanical properties such as storage modulus and internal friction are of significant importance in order to ensure the safe service of the turbine engines
The polpolycarbosilane/xylene solution, as the precursor, utilized to infiltrate the coated ycarbosilane/xylene solution, as the precursor, waswas utilized to infiltrate the coated per◦ C to fabricate the performs in vacuum condition and subsequently pyrolyzed above forms in vacuum condition and subsequently pyrolyzed above 1000 °C to fabricate the compositesin in an an argon argon atmosphere
Summary
Turbine engines suffer severe dynamic loads caused by structural vibration and noise during service, and these vibrations should not exceed their resonance limit, so as not to damage the engine [1,2]. The dynamic mechanical properties such as storage modulus and internal friction are of significant importance in order to ensure the safe service of the turbine engines. Internal friction (i.e., damping) is regarded as one of the most important dynamic mechanical properties and refers to the conversion of vibration energy into internal energy during mechanical vibration. It can be used as a non-destructive testing method to study material microstructures due to the sensitivity to the variation of microstructure [3,4,5].
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