THERMAL FATIGUE DAMAGE UNDER A TWO-STRAIN-BLOCK HISTORY.
Final rept. 1 Jul 63-1 Jul 67,
SEATTLE UNIV WASH DEPT OF MECHANICAL ENGINEERING
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Thermal-strain fatigue, two block strain cycling, axial tension-compression tests were performed on thin-walled tubes of annealed, type 200 nickel to study the plastic strain damage process that leads to failure in the range of 10,000 to 100,000 cycles at a mean temperature of 580F under a frequency of 60-90 cycles per hour. Plastic strain ranges are in the order of twenty to forty per cent of the total strain range. All tests showed a transient period in the first 100 cycles prior to the stress-strain hysteresis loops stabilizing. A cumulative damage theory was developed which led to the relationship for a two-strain block history. Author
- Metallurgy and Metallography