Vibration Analysis of Simple Home Generator

Abstract

AbstractThis research presents an analysis for the vibration of a small electricalgenerator, which is widely used for domestic purposes. This generator is of a type(ASTRA 3000) that gives an electrical power up to (2200 W), The analysis isachieved by using the method of the transfer matrices. The generator consists ofarotating system, abody cover (casing) and bearings so a mathematical model hasbeen built accordingly. The mathematical model consists of two beams connectedto Each other with some springs and dampers where the rotating system has beenrepresented by rotating beam under the gyroscopic moment effect, but the bodycover is represented by a non-rotating beam. And each bearing has two stiffnesscoefficients and two damping coefficients This model also considers the effect ofsupporting braces for the body cover which is represented by a flexible spring anddamper. The generated magnetic relucting force has been calculated and convertedto flexible springs which are accounted for in the prepared model.The current research studied the effects of the instantaneous changeable electricalload and the stiffness of the supported plastic pieces, on the critical speeds and their mod shapes and the dynamical characteristic values of the vibrated system allover the rotating length and the casing with the existing of the exciting forces. Alsoa comuter program has been developed by (New Fortran) language to embrace thetheoretical work and from which the values of shear forces, the bending moments,deflections and slopes can be calculated over the entire length of the rotatingsystem and casing.It is concluded that: the change of the electrical load affects thecritical speeds values and the response of the generator. It has also been found thatthe extreme values of the stiffness of the plastic pieces according to their originalvalues decline the critical speed values. However, there is a value little less than theoriginal value, increasesthe critical speed values.