On flexible input shaft and flywheel interaction in high-speed machines

While some elasticity in the coupling shaft between the driving motor and the machine input is desirable for attenuating the effects of misalignment, impact, etc. it is important to understand the resulting kineto-elastodynamic response of the machine for better design of the input shaft. One reason a flywheel is frequently used is to minimize the perturbations in the desired input motion. The elasticity in the coupling shaft interacts with the inertia of the flywheel to cause fluctuations in the desired machine motion. An improper selection of system parameters could result in adverse vibrations. In the approach described herein, an analytical indeterminacy arises owing to the fact that the input shaft motion dictates the requisite driving torque, which in turn controls the torsional vibration of the shaft. An iterative approach is used to arrive at the steady-state response of a machine with an elastic driving shaft. Once the vibratory response is known, a parametric study is conducted that would aid in a better understanding and an optimal design of the input shaft and the flywheel. Parameters such as the angular twist per unit length and the frequency and damping ratios has been considered.