Sensitivity of Torsional Analyses to Uncertainty in System Mass-Elastic Properties

Abstract

Shaft torque and corresponding stresses in a motor driven - direct coupled - reciprocating compressor system, are significantly influenced by the system’s mass-elastic properties. Uncertainty in the system’s mass-elastic properties will therefore translate into uncertainty in the calculated system stresses. Three case studies provide the reader with an appreciation for the importance of defining uncertainty bands in the mass-elastic properties of a torsional system. The case studies are followed by a theoretical discussion section. The reader is introduced to the concept of torsional resonance, uncertainty in calculated system torsional natural frequencies is defined, and the relative influence that specific system mass-elastic properties have on the overall system is discussed. A full compliment of system mass-elastic uncertainties is presented.

Experimental Study of the Shaft Penetration Factor on the Torsional Dynamic Response of a Drive Train

“…Hence, different coupling types or sizes can be tested. Two large cross-beams (12) and (14) can be mounted onto a single shaft section. In order to set up the moment of inertia of the system, every side of a cross-beam can be fitted with a specific mass (7) and (10) on a predefined distance relative to the center axis.…”

“…Similarly, Vance et al [11] concluded that an interference fit will have a significant effect on a system's lateral rotor dynamic behavior. In [12], the uncertainty of system mass-elastic properties on the outcome of numerical torsional analyses was discussed. Among some other uncertainties, it was pointed out that the shaft penetration factor has a significant influence on the first torsional eigenfrequency.…”