Use of Natural Vibrations in Flaw Detection of Heat-Stressed Equipment

Abstract

A method of nondestructive testing of the elements of a construction to which there is no direct access is presented. The method utilizes natural vibrations of the construction that have been excited by impacts of a special head of a hammer at specific spots. The method comprises a certain sequence that determines the position of the points of application of the impacts and measurements of the vibrations, the distribution of the frequencies of the vibrations by range, and the construction of a limited number of ranges of the spectrum of frequencies of the natural vibrations. The state of a controlled element of the construction is determined from the distributionof the frequencies of the natural vibrations in the spectrum. Results of experimental investigations of the inner jackets of eight nozzle heads by means of this method are presented.