The research in the dynamics of the gear transmission system has generated a wealth concerning the gear vibrations. Boyd and Pike [15, 16], and Choy [17] used the work done by Cornell [18, 19] to study the dynamics of multimesh gear transmission systems. Mark [20] applied the transfer matrix method to study gear system dynamics. In case of gearbox vibration analysis, some work using finite element analysis has been reported by Lim [21]. The study of gearbox vibration was developed by considering the coupling between the gear system and the casing [22-24]. The global dynamics of a gear transmission system was studied in [23] using the modal analysis.

The need to increase the reliability of the gear transmissions encouraged extensively the experimental studies of gear vibration. Some works [25-28] have performed the experimental study of vibration in gear system. The experimental and analytical studies of the vibration due to faulty gear have been presented in several literatures [26, 27, 29].

The study of vibration due to fault component in gear-bearing system is somewhat limited [30-33]. Additionally, none of work has been concerned the combined effect of bearing fault, shaft damage, and gear tooth damage in a rotor transmission system.

1.3 Research Objectives

In order to develop an on-line health monitoring to detect the combination effects due to defect in bearing, shaft and gear in the gear-rotor transmission system, it is necessary to understand the fundamental characteristics of fault condition generated by each component. The work in this research presents the development of dynamic simulation of transmission systems under the effects of localized defect in bearing element, shaft residual bow, and imperfection in gear tooth profile and the validation of numerical results by those of experiment. Also, the vibration signatures of each case obtained from both numerical simulation and experiment are analyzed by using either frequency method or Wavelet Transform and then the characteristic results of each case are used to classify root course under combination effects.

The accomplishments of this study can be summarized as follows:

·Develop the numerical simulation procedure for rotor-bearing transmission systems with the effect of localized defect in bearing element and validate the results with those obtained from experiment. 

·Develop the fault investigation methods suitably for bearing defect scenario.·Develop the numerical simulation procedure for rotor-bearing transmission systems with the effect of residual shaft bow and validate the results with those obtained from experiment.

·Develop the fault investigation methods suitably for residual shaft bow scenario.·Develop the numerical simulation procedure for gear-rotor-bearing transmission systems with the effect of gear tooth geometry imperfection and validate the results with those obtained from experiment.

·Develop the fault investigation methods suitably for gear tooth defect scenario.·Develop the numerical simulation procedure for gear-rotor-bearing transmission systems with the combination effects of localized defect in bearing element, shaft residual bow, and gear tooth geometry imperfection.·Identify the fault characteristic in dynamic signature obtained from combination scenarios in defected

components of bearing, shaft, and gear.

CHAPTER II

2.1 Overview

BACKGROUND OF MODAL ANALYSIS OF ROTOR-BEARING SYSTEMS AND VIBRATION SIGNATURE ANALYSIS

In the design of rotating machinery and other high speed turbo machinery, the machinery is often operating through several rotor critical speeds in order to reach its full power operating level.

Determination of the motion response of the rotor system is important for a design point of view so the equations of motion were developed and continuously improved for obtaining solutions close to actual system response.