A method is derived to detect and localize linear damage in a structure using the measured modal vibration parameters. This method is applicable when the vibration strain energy is stored in the axial or torsional modes, which differentiates it from previously derived strain-energy-based methods. The new method is compared to the previously derived flexibility-change method for comparison. Both...

In the resonance ratio control, which we proposed for vibration suppression and disturbance rejection in torsional system, the estimation speed of the disturbance observer should have been much faster than the resonance frequency of the controlled system. However, too fast disturbance observer sometimes causes implementation problem. In this paper, we give the optimal speed of the disturbance o...

This paper studies the dynamical response of a rotary drilling system with a drag bit, using a lumped parameter model that takes into consideration the axial and torsional vibration modes of the bit. These vibrations are coupled through a bit-rock interaction law. At the bit-rock interface, the cutting process introduces a state-dependent delay, while the frictional process is responsible for d...

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...

This paper discusses a detailed study carried out on vibration characteristics of transversely loaded pultruted composite beams. A considerable discrepancy was noticed in the measured vibration of the transversely loaded beam and the calculated natural frequencies of the beam using Euler-Bernoulli beam theory. It has been observed that the natural frequencies of the beam were increased after la...

Micro-cantilevers are frequently used as scanning probes and sensors in micro-electromechanical systems (MEMS). Usually micro-cantilever based sensors operate by detecting changes in cantilever vibration modes (e.g., bending or torsional vibration frequency) or surface stresses when a target analyte is adsorbed on the surface. The catalyst for chemical reactions (i.e., for a specific analyte) c...