creep damage

thermal fatigue

thermal fatigue
Stages of thermal fatigue or blade creep on a typical turbine blade. In the primary stage the initial rate of creep decreases rapidly, in secondary stage the rate decreases more slowly or may be substantially constant and in tertiary stage, the rate increases rapidly and leads eventually to fracture.
A kind of metal fatigue caused by repeated heating and cooling. It is prominent in turbines where some heating or cooling takes place each time a power setting is changed. Also called creep damage. See also creep (ii).
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In the combined-cycle industry modified 9Cr-1Mo is often seen as a silver-bullet remedy for two major troubles plaguing large heat recovery steam generators (HRSG): 1) the thermal fatigue of thick-walled components, such as main steam piping and superheater headers; and 2) creep damage in the superheaters.
As is expected, majority of these failures had creep damage as the primary mode of failures.
Though slipped deadlines, blown budgets and feature creep damage the bottom line, organizations often are reluctant to mess with their project processes," says Ben Snyder, Systemation's CEO.
Safe extension of operating lifetime requires new inspection techniques that can detect creep damage in service.
C ) conducive to causing creep damage over the operating life of the component.
CreepTest will seek to apply time reversal focusing and full matrix capture techniques that have already shown a capability to identify early stage creep damage.
To produce a field prototype NDE ultrasonic array system, signal processing and software for the examination of power plant steam pipe welds for creep damage.
The topics include the time-temperature-age superposition principle for predicting the long-term response of linear viscoelastic materials, predicting the viscoelastic behavior of polymer nano-composites, fiber-bundle models to analyze creep rupture in polymer matrix composites, the continuum-damage mechanical modeling of creep damage and fatigue, accelerated testing methodology for predicting long-term creep and fatigue, and monitoring the structural health of composite structures for durability.
Creep damage in the mean stress tests conducted was insignificant at room temperature for both materials.
the fraction of creep damage in each mean stress fatigue test was computed based on Eq.
These inspections are largely targeted at detecting late stage creep damage in which cracking is active in the component and provides qualitative rather than quantitative data.