Fatigue Performance Analysis of Hoop-Wrapped Composite Cylinders With Pit Defects on Liner Based on Element Birth and Death Method

Pit defects due to corrosion may occur in the inner surfaces of metal liners of fiber wrapped composite cylinders during working process, which may affect their anti-fatigue performance. Finite element method was used to analyze the stress of hoop-wrapped composite cylinders with pit defects of different sizes based on element birth and death method to take the pre-stress resulted from autofrettage process into consideration. Numeral results show that stress concentration appears in the pit defects, but the portion of the liner far away from pit defects keeps the same stress level with the defect-free composite cylinder. Pit defects on liner reduce the fatigue performance of the composite cylinder. Goodman equation was utilized to calculate the equivalent alternating stress amplitude to evaluate the variation of the fatigue performance with the dimensional change of the pit defects in the inner surfaces of metal liners of hoop-wrapped composite cylinders.