Abstract
Machine condition monitoring and fault diagnosis of rotating machinery are very important because of the wide use of rotating machinery in industry. Couplings and gears are used in many mechanical systems to connect elements and transmit power. The system is usually modeled as a single-degree-of-freedom system with a piecewise linear spring property, where the mass of main machine is only considered. In the present study, the dynamic behavior of a system with an unsymmetrical nonlinearity and a significant mass of the connecting part was investigated both experimentally and by numerical simulation. In the experiment, a 1/3 sub-harmonic oscillation was observed, but this oscillation was not found in the simulation using a single-degree-of-freedom system, in which the mass of the connecting part was ignored. However, when a two-degrees-of-freedom system was used that considered both the mass of the connecting part and the impact property, the 1/3 sub-harmonic oscillation was observed. Thus it is recognized that an adequate mathematical model for diagnosis in the early stage of abnormality must be selected on the basis of the mass ratio between the connecting part and the main body.
Highlights
Machine condition monitoring and fault diagnosis of rotating machinery are extremely important because of the wide use of rotating machinery in industry
The effects of unsymmetrical clearance on dynamic behavior are investigated based on the experimental results
A 1/3 sub harmonic oscillation has been observed experimen tally in a reciprocating systems, while 1/2 sub harmonic oscilla tions have appeared in simulation of a single degree of freedom system
Summary
Machine condition monitoring and fault diagnosis of rotating machinery are extremely important because of the wide use of rotating machinery in industry. If the condition of a system be comes abnormal, a nonlinear vibration often arises, and fault detection and diagnosis by monitoring any nonlinear vibrations is an effective approach. It is important to identify abnormal condi tions involving connecting parts as early as possible because any damage to them has a great influence on rotating machinery. The flexible material between a diving element and a driven one is modeled as a soft spring. The shaft which connects the driven element of coupling and main machine is modeled as a hard spring. This system has a piecewise linear spring property, which is a nonlinear property
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
