Analysis of Dependence between Stress Change and Resonance Frequency for Self-Excited Acoustical System

Abstract

Continuous supervision of mechanical endurance is very important in the time of the advance constructions. The Self-excited Acoustical System (SAS) is a kind of a self-oscillating system, which uses the auto-resonance phenomena for measurement of construction stress changes. The advantage of this solution is the ability to apply it to a wide spectrum of materials from elastoplasts to brittle ones where the conventional techniques cannot be used. The Self-excited Acoustical System is characterized by its great sensitivity in comparison with the traditional techniques. This paper presents the results of the research carried out on a metal bar expanded by variable force. The dependence between the relative elongation of the sample and the transition time of the wave was elaborated. The delay occurring during a wave transition has a direct impact on the value of self-oscillation frequency. The influence of the coupling force between a metal sample and the wave receiver was also analysed.