Abstract: The service conditions of bellows for vacuum interrupters are complex, and it is difficult to accurately predict their fatigue life by traditional theoretical calculation methods and experimental methods, which restricts the design and selection of bellows to a certain extent. In this paper, using digital image correlation (DIC) technology, based on tensile experiments and fatigue experiments, the SN curve of the bellows member was refined and obtained. Based on the ANSYS finite element analysis software, the finite element model of the elastic-plastic deformation of the bellows was established. The accuracy of the model is combined with nCode DesignLife to predict the fatigue life of bellows and verify its accuracy. The distribution evolution law of key process parameters (pressure, displacement, speed) on the stress, strain and fatigue life of the bellows in key characteristic regions such as wave crests and wave troughs is studied. The research shows that under the condition that only external pressure is applied to the bellows, fatigue damage is more likely to occur on the inner wall of the wave crest, and the displacement load has a more significant influence on the stress-strain distribution of the bellows. When the loading displacement is constant, the greater the speed, the greater the equivalent stress of the bellows. At this time, the external pressure of 0.2 MPa is coupled to offset part of the stress concentration. Under the external pressure of 0.2 MPa, when the compression speed increases from 0.5 m/s to 4 m/s, the maximum equivalent stress increases from 378.89 MPa to 424.27 MPa, and the fatigue life decreases from 49 540 cycles to 3 064 cycles.

Key words: bellows, finite element, S-N curve, fatigue life