Preloading Technique as a Tool to Identify Failure Mechnisms in Constant Stress-Rate Testing of Advanced Ceramics at Elevated Temperatures

2008 ◽  
pp. 91-99 ◽  
Author(s):  
Sung R. Choi ◽  
John P. Gyekenyesi
Keyword(s):  
Elevated Temperatures ◽  
Constant Stress ◽  
Stress Rate ◽  
Advanced Ceramics ◽  
Rate Testing

Accelerated Testing Methodologogy in Constant Stress-Rate Testing for Advanced Structural Ceramics: A Preloading Technique

2001 ◽  
Author(s):  
Sung R. Choi ◽  
John P. Gyekenyesi ◽  
Dean Huebert ◽  
Allen Bartlett ◽  
Han-Ho Choi
Keyword(s):  
Elevated Temperatures ◽  
Fatigue Testing ◽  
Constant Stress ◽  
Accelerated Testing ◽  
Stress Rate ◽  
Strength Increase ◽  
Additional Tool ◽  
Significant Strength ◽  
Rate Testing ◽  
Lower Test

Preloading technique was used as a means of an accelerated testing methodology in constant stress-rate (“dynamic fatigue”) testing for two different brittle materials. The theory developed previously for fatigue strength as a function of preload was further verified through extensive constant stress-rate testing for glass-ceramic and CRT glass in room-temperature distilled water. The preloading technique was also used in this study to identify the prevailing failure mechanisms at elevated temperatures, particularly at lower test rates in which a series of mechanisms would be associated simultaneously with material failure, resulting in significant strength increase or decrease. Two different advanced ceramics including SiC whisker-reinforced composite silicon nitride and 96 wt% alumina were used at elevated temperatures. It was found that the preloading technique can be used as an additional tool to pinpoint the dominant failure mechanism that is associated with such a phenomenon of considerable strength increase or decrease.

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