Transverse vibrations induced by longitudinal excitation in beams with geometrical and loading imperfections

Suppressing Flow-induced Vibrations by Parametric Excitation

The possibility of suppressing self-excited vibrations of mechanical systems using parametric excitation is discussed. We consider a two-mass system of which the main mass is excited by a ow-induced, self excited force. A single mass which acts as a dynamic absorber is attached to the main mass and, by varying the stiiness between the main mass and the absorber mass, represents a parametric exc...

Longitudinal-Torsional and Two Plane Transverse Vibrations of a Composite Timoshenko Rotor

In this paper, two kinds of vibrations are considered for a composite Timoshenko rotor: longitudinal-torsional vibration and two plane transverse one. The kinetic and potential energies and virtual work due to the gyroscopic effects are calculated and the set of six governing equations and boundary conditions are derived using Hamilton principle. Differential quadrature method (DQM) is used as ...

Coupling of flexural and longitudinal wave motion in a periodic structure with asymmetrically arranged transverse beams

Excitation of molecular vibrations by positron impact.

Absolute cross sections for the vibrational excitation of CO, CO2, and H2 by positron impact are presented for incident positron energies from 0.5 eV to several electron volts. The measurements use a novel technique that exploits the adiabatic motion of a positron beam in a strong magnetic field. This work is the first systematic experimental study of vibrational excitation by positron impact, ...

Optimization of slender structures considering geometrical imperfections

In this article, we present an optimization model which incorporates uncertainty induced by geometrical imperfections. Within the model, geometrical imperfections are represented by means of random fields. The induced uncertainties are then treated using the concept of a convex model. The resultant problem is then solved in a two-stage optimization procedure. An arched girder is used to demonst...