Ultrasonic measurement method for plane stress on the basis of multi-wafer air-coupled transducer

Abstract

An ultrasonic measurement method for plane stress on the basis of a multi-wafer air-coupled transducer relates to the technical field of ultrasonic testing. The method solves problems that a traditional measurement method for plane stress generally computes the plane stress by changing at least 3 different measurement directions and obtaining information such as an acoustic time difference in the 3 measurement directions by using a pair of contact ultrasonic transducers, which is too complicated in operation, and a coupling agent can influence measurement accuracy of the plane stress. The method includes: emitting, by an excitation signal transmission end, an ultrasonic wave passing a wafer of the multi-wafer air-coupled transducer to a member to be measured; receiving, by an excitation signal reception end, an echo returned from the member to be measured through a corresponding wafer of the multi-wafer air-coupled transducer; obtaining an acoustic time difference of lamb waves through data processing according to the ultrasonic wave and the echo; and obtaining first principal stress, second principal stress and an included angle between the first principal stress and a fiber direction of an orthotropic composite material according to the acoustic time difference of the lamb waves. The method is suitable for the field of plane stress testing.