Dynamic analysis of mechanical system by finite element method

The present study is concerned with a free vibration of twistedturbine blade numerical! y and experi menta II y. The numerical solutionprocedure follows the finite element method, a typical structuralmodel of the turbine blade is used and the turbine blade is dividedinto twenty rectangular elements.The numerical results of the first five natural frequencies,displacement shapes, rotations, shear forces and the internalmoments for two cases as; the case of the actual turbine blade andthe case of blade with variable thickness including the effect of thedifferent twist angles upon it were obtained.An experimental work was carried out. It consists of a specialhummer, the turbine blade is fixed in a special fixture manufacturedto accommodate the blade, accelerometer is fixed on the blade and theaccelerometer amplifier is connected to frequency function analyzer.The experimental values for the first five natural frequencies weremeasured. The comparison between these experimental values and thenumerical results found an agreement between them.