考虑空间形位偏差的万能式断路器关键零件断裂失效研究

During the closing process of an air circuit breaker (ACB), energy stored in main spring is transferred to four-linkage mechanism through its driving shaft in the form of impact. Position deviations on the striking rod caused by machining and assembly tolerance lead to the fatigue and the final fracture of the driving shaft. This makes operational lifespan of the mechanism inconsistent with the expected design one. Based on multi-body dynamics, a virtual prototype model of the mechanism is established. Accuracy of the virtual prototype is verified by testing rotational positions of two shafts around which the energy storage lever and the linkage shaft rotate. Then, using the measurement data, the spatial deviation range of the end point of the driving shaft relative to the roller is obtained. Then the virtual prototype parameters are used to model the deviation, and the variation of peak load and crack initiation period is calculated. Finally, it is assumed that there is an elliptical-type crack on the driving shaft, and the influence of the deviation on the SIF at the crack tip is studied. In this paper, the influence of the spatial deviation of the driving shaft on its fracture process is given, which can provide theoretical guidance for design and manufacturing.