MODELING AND ANALYSIS OF THE INTERMEDIATE SHAFT BETWEEN 2 UNIVERSAL JOINTS

Unlike a single universal joint, in which the output shaft rotates wit h a fluctuating speed depending on the misalignment angle, a double un iversal joint is used to connect two offset shafts. If a double univer sal joint is correctly arranged with equal joint angles in perfect ali gnment, the output shaft rotates in a synchronous motion with uniform speed. However, in practice, the intermediate shaft of a double univer sal joint system suffers from bending moments induced by joint frictio n and velocity fluctuation induced by the joint angles. These factors distort the linear relationship between the input and output shafts. I n this paper, the effects of joint angles and joint friction on the st eady-state responses of a double universal joint system are examined. The mass matrix, damping matrix, stiffness matrix, and nonconservative force of a universal joint are derived analytically for finite elemen t modeling. The formulation introduced generates an elementary matrix suitable for the analysis of complex rotor-bearing system's that inclu de double universal joints.