We calculate the spectrum of torsional vibrations of a double-stranded structure that models the double helix of the DNA. We come to the conclusion that within the framework of the model elementary exictations may display an asymmetry as regards their winding and direction of the propagation, depending on initial polarization. The asymmetry could have a bearing on processes that take place in m...

Nonlinear dynamic model of the coupled lateral-torsional vibrations of a gear transmission system is developed, in which time-varying gear meshing stiffness, errors, and gaps are considered. The fundamental rules of the system’s multi-harmonic dynamic response have been obtained based on the time domain diagram, frequency domain diagram, phase plot, and Poincaré map. Therefore, estimation of th...

This paper reports the design, simulation, fabrication, and experimental testing of a low-frequency piezoelectric energy harvester fabricated using screen-printing technology. A centrally supported meandering geometry is chosen to reduce the torsional mode effects during the unit vibrations and to achieve better power efficiency. The design experiences alternating stress along the beams and a s...

We establish a homogenization result and a corrector result for a vibration problem of elasticity. We assume that the data depend in a periodic way on a small parameter ε. We assume also that the Lamé coefficients take possibly high values in a periodical set of disconnected inclusions and take values of the order ε2 elsewhere. In the fibered case, torsional vibrations take place at an infinite...

Many methods exist for the experimental determination of the viscoelastic properties of materials. Some of these methods have been summarized [1,2]' and those that have been used more recently appear in a collection of abstracts [3]. The method described herein, which uses forced torsional vibrations, is an updated version of previous works [4,5]. It was selected because it most easily met the ...

A parameter study is presented to determine effects of planet gear design parameters on the global modal behaviour planetary geared rotor systems. The sensitivity analysis conducted using a three-dimensional dynamic model system for number gears, mistuning, mass mesh stiffness and speed. These have varying impacts both natural frequencies mode shapes, therefore vibration modes determined by com...

This paper proposes a novel method for the unbounded oscillation prevention of an aircraft wing under flexural torsional flutter, innovative multiagent attitude to control with surface consisting managed rotating “feathers” (agents). Theoretical evaluation demonstrates its high aptitude avoid wing’s flexural-torsional vibrations via expansion model’s ability dampen oscillations. It potentially ...

Torsional vibrations of drill-strings are actively controlled using a non-switching sliding mode strategy. The controller is intended also to reject the effect interaction between drill-bit and rock formation which induces non-linear stick-slip friction torque while tracking desirable constant angular velocity drill-string. In order demonstrate merits proposed control algorithm, it integrated w...