Experimental Study on Crack Detection at Bolt Hole Edge in Rail Joint Using the Third Harmonic

Abstract

Abstract In this paper, a nonlinear ultrasonic detection method for detecting the hole edge crack in rail joint was proposed. The experimental results show that a single frequency sinusoid wave modulated by Hanning window is input to the rail specimen, there are higher order harmonics in the received signals for cracked rail, but there are no any harmonics for the rail with no crack bolt hole. That is to say the higher order harmonics can be used to indicate the presence of a crack. Furthermore, a nonlinear parameter μ is defined by the ratio of the third harmonic frequency peaks to the peak of the fundamental frequency. The relationship between nonlinear parameters and crack size is approximately linear, which means that the third harmonic not only can detect the presence of the hole edge crack, but also can assess the size of the hole edge crack.