Paper: ASAT-15-168-ST 15 th International Conference on AEROSPACE SCIENCES & AVIATION TECHNOLOGY, ASAT - 15 – May 28 - 30, 2013, Email: asat@mtc.edu.eg , Military Technical College, Kobry Elkobbah, Cairo, Egypt, Tel: +(202) 24025292 –24036138, Fax: +(202) 22621908 1 FE and Experimental Modeling of On-shaft Vibration Measurement M. E. Elnady * , A. Abdelbary * , J. K. Sinha † , S. O. Oyadiji † Abstract: Vibration-based condition monitoring is a well-accepted tool for diagnosing rotating machines faults. Measuring vibration on the bearings uses multiple sensors and needs skilled personnel for data collection, processing and interpretation. An analytical model for the alternate method of On-Shaft Vibration Measurement is presented. The model is validated through FE and experimental analysis. The results show that the model efficiently represents the measurement process. Keywords: Vibration-based condition monitoring, on-shaft vibration measurement, MEMS accelerometer, wireless sensor nodes. 1. Introduction 1.1 Vibration-Based Condition Monitoring Rotating machines form the backbone of almost all mechanical systems. Usually, wherever motion is required, a rotating machine would exist running smoothly and efficiently to provide the motive force. For Vibration-based Condition Monitoring (VCM), the vibration sensor is placed on the bearing pedestals and the shaft vibration is indirectly measured. In some cases, it is directly measured from the shaft itself. Mitchell [1] discussed measurement arrangements for commonly monitored machines (centrifugal pumps, axial compressors, fans, gas generators, etc.). These setups lay within On-Bearing Vibration Measurement (OBVM) which is a reliable condition monitoring tool, however some limitations are observed: a) Highly experienced personnel are required to collect and analyze the data. b) On-bearing sensors are generally affected by structural noise propagating through the machine hull. c) A considerable space is needed for the system components and cabling. d) The system capital and maintenance costs are relatively high. e) One of the ways to enhance the Faults Diagnosis (FD) is to increase the number of sensors [2]. However, this necessitates exhaustive signal processing work. f) More research is required to identify robust and unique fault features especially when multiple faults coexist. For these reasons, vibration analysts have been dreaming of a method to capture the shaft vibration directly without being affected by bearing and structure imperfections, journal bearing damping, structural noise, etc. Also, reduction of the installed sensors merely minimizes the system maintenance cost and the signal processing. * Egyptian Armed Forces, Egypt. † University of Manchester, UK.