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

Abstract

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.