FatiguePro Stress-Based Fatigue Module

Stress-based fatigue monitoring consists of computing a "real time" stress history for a given component from actual temperature, pressure, and flow histories. Fatigue usage is then computed from the computed stress history using appropriate techniques. This methodology is more exhaustive from a computational standpoint than cycle-based fatigue usage, and is intended for high-fatigue components where a more refined approach is necessary to show long-term structural acceptability. In effect, this method of fatigue usage calculation provides "on-line" stress analysis similar to that used in design stress reports.

The heart of the stress-based fatigue monitoring technique is the transfer function / Green's function approach that is utilized to convert plant data to peak stress versus time at the monitoring locations. With this technique, the peak stresses are divided into two parts: (1) stresses due to component loads and internal pressure, and (2) stresses due to thermal transients.

Typical locations monitored with stress-based fatigue are summarized below:

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