Thermoelastic finite element fatigue failure analysis

Finite element analysis software has given not only the design engineer, but forensic engineers as well, a tool for analyzing complex situations. However, even with such advanced analysis tools, the engineer is often required to adapt the results to accommodate a specific situation. For instance, finite element analysis is excellent at examining static or dynamic loads against a failure criteria. However, in situations such as fatigue multiple loadings must be combined to develop the failure stresses. This is rather easy to do for one loading case that is completely reversed. However, for multiple loadings that are not reversed, other methods must be developed to augment the finite element analyses. Using such an augmented approach, a thermal fatigue failure of a gas-fired heat exchanger was accomplished. This paper details the procedure followed.