Измерение коэффициента затухания ультразвуковых волн в неоднородных материалах при одностороннем доступе

Abstract

The article considers an improved method for measuring the ultrasonic wave attenuation coefficient in objects made of materials with a heterogeneous structure under the conditions of unilateral access to objects. The method is primarily aimed at assessing the structural condition of critical bulky objects made of concrete, cast iron, and other intricately structured materials with a view to prevent possible accidents and disasters. The ultrasonic wave attenuation coefficient is determined by processing the realizations of structural noise resulting from the reflection of a probing signal from numerous heterogeneities in the object. The article suggests an improved algorithm for processing the realizations of structural noise, the use of which makes it possible to obtain better accuracy of measurements, to expand the applicability limits of the method, and to simplify the received signals processing procedure. Matters concerned with optimizing the probing signal parameters and the transducer characteristics are studied. A number of experiments were carried out for checking the efficiency of the proposed method and of the new algorithm for processing structural noise realizations. Measurements of the longitudinal ultrasonic wave attenuation coefficient in a specially fabricated concrete block were carried out. The measurements were carried out using two methods: the classic shadow method and the proposed method based on processing the structural noise realizations. The experiments showed good results: the measurement accuracy has been improved by almost 10 times compared with the previous version of the proposed method. The most appropriate application field of the proposed method is monitoring the structural state of critical bulky objects made of materials with a heterogeneous structure like dams and bridge supports under the conditions in which it is impossible to apply other ultrasonic non-destructive testing methods, e.g., those based on ultrasonic wave velocity measurements.