A Parametric Study of High Cycle Thermal Fatigue Caused by Thermal Striping

Abstract

A numerical scheme is developed and evaluated for fatigue analysis due to thermal oscillation. This model uses calculated instantaneous coolant temperatures at a pipe surface, and then calculates the pipe wall temperature response, stress and stress intensity factor (SIF) separately. A crack propagation correlation is then applied to calculate the initial and final crack size. The model is a useful tool in identifying the relative importance of various parameters affecting fatigue crack failure. Effects of the heat transfer coefficient, the magnitude and frequency of temperature oscillations and the system pressure were evaluated. Results show that the heat transfer coefficient and the magnitude of temperature oscillations are correlated to each other and have a dominant effect on thermal fatigue failure. Also it is found that the frequency can be hazardous within a given range and the increase of system pressure has an adverse effect on the potential failure.