Patent ID: 11946735
Assignee: SOUTHWEST JIAOTONG UNIVERSITY
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 3:
4. The method for measuring the deviation angle of the fatigue microcrack based on the nonlinear ultrasound according to claim 1, wherein the step S5 specifically comprises:
S51: analyzing the xth group of time domain waveform signals, and converting the signals into a corresponding frequency domain graph, wherein x is the number of change times of the orientation angle αx, and x=0, 1, 2, . . . , n;
S52: extracting the ultrasonic fundamental wave signal amplitude A1x and the second harmonic waveform amplitude A2x from the xth group of frequency domain graph data, wherein a fundamental wave signal frequency is close to a center frequency of the excitation sensor, and a second harmonic frequency is twice that of the fundamental wave frequency;
S53: obtaining the xth group of relative nonlinear coefficients β′x by calculating according to, β
    x
    ′
   
   =
   
    
     A
     
      2
      ⁢
      x
     
    
    
     A
     
      1
      ⁢
      x
     
     2
    
   
  
  ;
 

 and
S54: repeating the step S51 to the step S53, and calculating n+1 groups of relative nonlinear coefficients in total.