Stress and fatigue analysis of bellows with volume defects

To evaluate the safe operation of metal bellows expansion joints with volume defects, the stress and fatigue life were studied. In this study, the stress and fatigue characteristics of bellows with volume defects were studied by using the finite element method combining static analysis and nCode fatigue analysis module. The research shows that under the working conditions of internal pressure of 0.9 bar, temperature of 154.5°C, axial displacement of ±20 mm, and transverse displacement of ±18 mm, the stress at the joint of metal bellows expansion joint and straight pipe segment is the largest, and its size is 441.8 MPa. Fatigue analysis under cyclic events shows that the minimum life of the metal bellows expansion joint is 725 cycles. The results of stress and fatigue life obtained by finite element calculation meet the expected requirements. Therefore, the evaluation method established in this paper is suitable for analyzing the stress and fatigue life of bellows expansion joints with volume defects.