Harmonics Of Resonance Frequency Research Articles

Impact of High-Frequency Vibrations on Metal Items Resistance to Cyclic and Axial Loads

It was shown that the forced vibrations of objects on resonance frequencies could significantly change resistance of these objects to cyclic loads in a low-cycle loading range and decrease critical compression load under axial compression. We carried out a procedure of fatigue testing performance with simultaneous application of high-frequency vibrations. We developed and produced a device allowing carrying out testing aimed to check shape stability of cylindrical shells and their resistance to forced vibrations. Dependence of fatigue life capability within the low-cycle range on the frequency of applied forced vibrations in four harmonics of resonance frequency was experimentally determined. Fatigue life capability decreased by 1,6 times. Decrease of life capability particularly occurs on frequencies which are presumably connected with minimum in size elements of hierarchy of polycrystalline material structures. It was found out that the forced vibrations on resonance frequency contribute the increase of a number of vibrations, that leads to decrease of critical axial compression force value. Decrease can be by up to 40%. Experimental determination of critical load during application of vibrations allowed obtaining formula for adjusting factor calculation in the formula for permitted compression force calculation.

Thickness shear modes and magnetoelastic waves in a bi-layered structure: magnetic film–non-magnetic substrate

Abstract Thickness modes of magnetoelastic waves in a bi-layered structure magnetic–non-magnetic material have been theoretically investigated. Plots illustrating the dependence of harmonics of resonant frequencies upon the magnetic layer thickness were constructed at various magnetoelastic wave vectors. A dependence of the dimensional resonance frequencies on the wave number of magnetoelastic waves propagating along the saturating field direction is found. Peculiarities of the resonant frequency harmonics behavior with varying magnetic layer thickness and number are analyzed. The multimode character of the thickness magnetoelastic resonances, attributed to the possibility of excitation of magnetoelastic waves with different wave number is discussed.

Excitation of dimensional resonances of magnetoelastic and elastic waves in bilayered structure

AbstractA study is made of the dimensional resonances of the thickness modes of shear magnetoelastic and elastic (MEE) vibrations in a bilayered structure: magnetic‐nonmagnetic dielectric. The efficiency of dimensional resonance excitation is considered. We show that the magnetic susceptibility of the thickness modes of shear MEE vibrations attains extreme values in the case when the position of an interface coincides with one half and one quarter of a MEE wavelength. The magnetic susceptibility calculated for the resonant frequencies changes in a nonmonotone way with the change of relative thickness of the magnetic layer. The form of nonmonotone regions depends on the relations between the elastic moduli of magnetic and nonmagnetic layers, the position of interface and differs for odd and even resonant frequency harmonics. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)