The vibration pattern of a rotor system reflects the mechanical parameter changes in the system. Hence, the use of vibration monitoring is considered as a possible means of detecting the presence and growth of the cracks. In this paper, a pattern search based method for shaft crack detection is proposed and described which formulates the shaft crack detection as an optimization problem by means...

Bicoherence or Bispectrum analysis is emerging as a new powerful technique in signal processing, especially in areas where traditional linear spectral analysis provides insufficient information. It is most effective in analyzing systems with non-linear coupling between frequencies. Faults in rotating machineries leave their signature on the vibration signal sensors and generally manifest themse...

In this paper, a new tool for crack detection in operating rotors based on wavelet theory is described. Customarily, two approximate methods of spectral analysis, i.e. ShortTime Fourier transform and Wigner distribution, have been used to analyse the vibration components of cracked rotors during run-up or run-down periods. However, for both methods, high resolution cannot be achieved simultaneo...

A computational study of helicopter vibration and rotor shaft power reduction is conducted using activelycontrolled trailing-edge flaps (acfs), implemented in single and dual flap configurations. Simultaneous vibration reduction and performance enhancement is demonstrated under level flight condition at high advance ratios, where dynamic stall effects are significant. Power reduction is achieve...

This paper analyzes the reason of Low-speed vibration in an electric vehicle, builds the mathematical equation of powertrain torsional vibration. Then, the model of torque ripple considering non-sinusoidal magnetic field distribution is built, orders and frequencies of torque ripple in PMSM is predicted. According to the relationship between the torsional vibration in low-speed of the electric ...

In this paper, exact solution for two-plane transverse vibration analysis of axial-loaded multi-step Timoshenko rotor carrying concentrated masses is presented. Each attached element is considered to have both translational and rotational inertia. Forward and backward frequencies and corresponding modes are obtained using transfer matrix method (TMM). The effect of the angular velocity of spin,...

The current paper studies the influence of annular seal flow on the transient response of centrifugal pump rotors during the start-up period. A single rotor system and three states of annular seal flow were modeled. These models were solved using numerical integration and finite difference methods. A fluid-structure interaction method was developed. In each time step one of the three annular se...

A study of the combined helicopter noise and vibration problem was conducted. A refined aerodynamic model capable of calculating the unsteady surface pressure distribution on rotor blade/flap combinations is developed and coupled with an aeroelastic analysis simulation code. An acoustic prediction tool based on WOPWOP is combined with the aeroelastic analysis based on a flexible blade with coup...