Dynamic Modeling and Analysis of Fixed–Fixed Rotor Shaft with Transverse Crack Rotating in Changed Fluid Environment using Fuzzy Logic Technique Approach

Current research work objective is identifying the crack position and crack depth in fixed–fixed rotor shaft rotating under altered viscous fluid medium using a Fuzzy logic technique. To evaluate the dynamic response of the cracked fixed–fixed rotor rotating under altered fluid medium utilizing the influence coefficient method. An external force of fluid is computed by Navier–Stokes equation. Local stiffness was determined using the strain energy release rate at the rotor shaft's crack location. The results of theoretical analysis have been verified using an experimental arrangement. To recognize the depth and location of the transverse crack, the fuzzy logic method was employed with relative natural frequency perpendicular to axis of crack, relative natural frequency parallel to axis of crack, relative amplitude of vibration at perpendicular to the axis of crack, relative amplitude at parallel to the axis of crack and viscosity of fluid as input parameter. The coefficients of correlation for Gaussian membership, triangular and trapezoidal functions are very near to one. Similarly, the total average error of three membership functions validate with the theoretical analysis results and error is found for all less than 7%. It has been shown that results attained from all three membership functions are to be close agreement to the results of theoretical depths and locations crack. Therefore the recommended fuzzy logic method would establish an effective tool for real-time crack detection in rotor.