Analysis of Moment Transmitted by Universal Joint in Varying Operating Condition

Abstract

The moments transmitted by a universal joint in varying operating condition was investigated. A model of shaft system driven by a universal joint which consists of a driving shaft, a driven shaft and a cross piece is chose. Both structure misalignment and error misalignment between the two shafts at the universal joint was considered, and the study was based on the assumption that friction, inertia and elastic forces of the cross piece were disregarded. Two pairs of Euler angles were introduced to denote structure misalignment and error misalignment respectively, sets of reference frames were built up on the driving shaft, driven shaft and cross piece. Using direction cosine matrixes to describe the relation between different frames, then the expressions of components of the transmitted moment acting on the driven shaft were obtained via method of vector projection. Based on engineering fact, the transmitted moment model was simplified with respect to different misalignment conditions, such as only structure misalignment or only error misalignment is considered. Then for different misalignment situations, the lateral and torsional components of the transmitted moment acting on the driven shaft were simulated through numerical examples. It turns out that both the lateral moment and torque components will fluctuate based on the import torque, and that due to accelerating of the driving shaft, the fluctuation of transmitted moment will be more distinct, consequently, more complicated nonlinear dynamics behavior will arise.