Effect of the Thermal Mean Stress Value on the Vibration Fatigue Assessment of the Exhaust System of a Motorcycle Engine

The exhaust manifold of a high-performance motorcycle engine is subjected to combined thermal and vibrational loadings. In this research, the whole fatigue assessment of an exhaust manifold is addressed. First, a classic low-cycle fatigue analysis is performed. Then, a specific methodology for determining the fatigue cycle of components subjected to thermal and vibration loadings is developed and presented in a way that possible damages can be evaluated. The results are post-processed and the damage caused by fatigue cycles is computed referring to the Wohler curve of the material using the Dirlik approach.