Non-linear vibration detector

Abstract

Abstract PURPOSE:To rapidly detect the flaw of a structure in a non-destructive manner, by a method wherein the complex operation and averaging of an introduced ultrasonic wave and the ultrasonic wave generated from an object to be measured are performed to calculate required coherence function which is, in turn, compared with reference coherence function to detect the non-linear vibration corresponding to a flaw. CONSTITUTION:The digital ultrasonic signal outputted from an object 19 to be measured by a receiving transducer 18 and the corresponding digital ultrasonic signal introduced by a transmitting transducer 17 through a delay circuit 4 are respectively processed by Fourier transformers 5, 6 to be set to spectrum values converted to a frequency region from a time region. A complex operator 7 determines the elements from formula I from said spectrum values by complex operation and the elements are averaged by an averager 8 and the coherence function c(f) based on formula II is calculated by a coherence function operation circuit 9. Then, the coherence function c(f) is compared with reference coherence function by a comparator 10 to detect the non-linear vibration corresponding to a flaw and, since scanning due to an ultrasonic wave is unnecessary, the flaw of a structure is detected rapidly in a non-destructive manner.

Inventors

• 👤 Yakichi Higo
• 👤 肥後　矢吉
• 👤 Aiichi Katayama
• 👤 片山　愛一

Bibliographic Details