Effective parameters on fatigue life of wire-wound autofrettaged pressure vessels

- Parameters on fatigue life of wire-wound autofrettaged vessels are investigated.
- Actual material behavior in loading, unloading and reloading is applied for vessel.
- By using proper design parameters, infinite fatigue life could be achieved.
- Applying an optimum autofrettage pressure has a significant effect on fatigue life.
- Adding a new layer of wire increases the fatigue life more than the previous layer.

In this paper, fatigue life of wire-wound autofrettaged vessels is investigated. The mutual and simultaneous effects of cylinder thickness, autofrettage pressure, number of wire layers, wire-winding stress, and working pressure are studied in several cases. The vessel cylinder is made of high strength steel, DIN1.6959, and actual behavior in loading, unloading and reloading is considered. Modified Variable Material Properties method is used to calculate residual stresses in autofrettage process. For wire-winding, since tangent and/or Young's modulus could be changed in autofrettage unloading step or during reverse yielding according to material behavior, a capable approach is applied. Moreover, the fatigue life is determined by using ASME code equations for tick-walled pressure vessels. The results show that by combination of wire-winding and autofrettage techniques, in addition to ability of reducing production costs, infinite fatigue life could be accessible. Furthermore, optimum autofrettage pressure has significant effects on fatigue life and wire-winding efficacy.