Planetary gears are widely used in mechanical transmission systems, but the vibration and noise affect their reliability life. In this paper, torsional dynamic model of an encased differential planetary gear with coaxial contrarotating outputs considering time-varying meshing stiffness, damping, phase difference all pairs is established. By solving equations derived system, three types natural ...

A Health and usage Monitoring System (HUMS) anticipates discrepancies in therotorcraft drive-train, giving the operator an opportunity to perform correctivemaintenance before any damage becomes critical. In addition to usage spectrum analysis,a HUMS deploys vibration monitoring as a means to detect propagating faults. Thismethod consists in comparing in-flight vibration reco...

A computational study of helicopter vibration and rotor shaft power reduction is conducted using actively-controlled trailing-edge flaps (ACFs), implemented in both 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 a...

This paper presents vibration analysis of an autoparametric pendulum-like mechanism subjected to harmonic excitation. To improve dynamics and control motions, a new suspension composed of a semiactive magnetorheological damper and a nonlinear spring is applied. The influence of essential parameters such as the nonlinear damping or stiffness on vibration, near the main parametric resonance regio...

This paper presents the development of an optimal self-tuning PID controller for vibration suppression of flexible manipulator structures using particle swarm optimization (PSO). A simulation environment characterizing the dynamic behavior of the flexible manipulator system was first developed using finite difference (FD) approach to acquire the input-output data of the system. The global searc...

A new structural control system using damper-installed shear walls in lower stories with reduced stiffness is proposed for vibration control of high-rise RC buildings. That system has some design variables, i.e., height of shear wall, degree of stiffness reduction at lower stories, and quantity of dampers. In this paper, some parametric studies on the shearbeammodel with a stiff beam against tw...

The Hamilton principle is applied to deduce the free vibration frequencies of a cantilever single-walled carbon nanotube (SWCNT) in the presence of an added mass, which can be distributed along an arbitrary part of the span. The nonlocal elasticity theory by Eringen has been employed, in order to take into account the nanoscale effects. An exact formulation leads to the equations of motion, whi...