Interpretation of Elevated Temperature Fatigue Data

摘要

The general problem of thermal cycling is examined in relation to component stress-strain response and failure development. The complexities of component failure analysis under thermal cycling conditions are clear. It is also clear that no single test procedure will enable good assessment and design rules to be delineated. More uniaxial plain specimen endurance data and simple crack propagation data are needed. But also more complex specimen test information is needed on specimens which simulate more closely the thermal stress-strain fields encountered in components. In addition, the role of environment and material metallurgical changes with time in long term failure development requires a better understanding. One inbuilt safety feature of many thermal cycling situations is the tendency to crack arrest conditions within the bulk material. The bounds on this factor are, however, not clear particularly when additional mechanical loads or constraints are present, as these can produce accelerating rather than decelerating crack conditions. (ERA citation 03:040299)