Imaging the Nonlinear Ultrasonic Parameter of a Medium

1983 ◽  
Vol 5 (4) ◽  
pp. 295-299 ◽  
Author(s):  
Nobuyuki Ichida ◽  
Takuso Sato ◽  
Melvin Linzer
Keyword(s):  
Spatial Frequency ◽  
Probe Beam ◽  
Pump Wave ◽  
Power Level ◽  
Ultrasonic Waves ◽  
Nonlinear Parameter ◽  
Probe Wave ◽  
Cross Sectional ◽  
Nonlinear Ultrasonic ◽  
Ultrasonic Parameter

A technique for imaging the nonlinear ultrasonic parameter B/A has been developed. The nonlinear parameter describes the dependence of ultrasonic velocity on pressure and may well provide a new and powerful tool for characterizing both biological and nonbiological media. Our approach is based on observing the interaction of two ultrasonic waves with different frequencies and power levels. A low frequency pump wave, with power level suitable for medical diagnosis (1 mW/cm2), is used to sinusoidally modulate the sound pressure over the region of interest. A much lower intensity high-frequency probe beam is propagated perpendicularly to the pump beam. The phase of the probe wave is modified in proportion to the integral of the product of the nonlinear parameter B/A and the pressure of the pump wave, which varies sinusoidally along the probe beam. This phase change provides a Fourier component of the distribution of the nonlinear parameter B/A for the spatial frequency corresponding to the inverse of the pump wavelength. By changing the frequency of the pump waves, the spatial frequency is changed and a set of spatial Fourier coefficients of the distribution of the nonlinear parameter B/A is obtained. An inverse operation then gives the one-dimensional image along the probe beam. If the probe beam is scanned mechanically, the entire cross-sectional image is obtained. Several images of the nonlinear parameter of biological objects were generated with our system. To our knowledge, these represent the first images of the nonlinear parameter to be reported in the literature. The nonlinear parameter of water was also measured and agreed well with values obtained by other techniques.

Measurement of Natural Vibrations and Resonant Second Higher-Harmonics Due to a Fatigue Crack

2020 ◽  
Vol 3 (4) ◽  
Author(s):  
Kosuke Kanda ◽  
Shan Lin
Keyword(s):  
Fatigue Crack ◽  
Frequency Response ◽  
Ultrasonic Testing ◽  
Characteristic Curve ◽  
Ultrasonic Waves ◽  
Local Defect ◽  
Response Characteristics ◽  
Local Defect Resonance ◽  
Nonlinear Ultrasonic ◽  
Frequency Response Characteristics

Abstract Nonlinear ultrasonic testing is considered a more promising technique for evaluating closed cracks than conventional ultrasonic testing. However, the mechanism of the generation of nonlinear ultrasonic waves has not been sufficiently explained. We first set up a system to measure the frequency–response characteristics of ultrasonic waves and experimentally investigated the mechanism of second higher-harmonic (HH) wave generation for a fatigue crack. Sweeping the frequencies of incident waves impinging on a fatigue crack introduced to a specimen, we obtained a frequency–response characteristic curve for the crack. From the curve, resonance phenomena resulting from local defect resonance were observed. We then measured the frequency response characteristics of second HH waves using the same system and consequently confirmed that second HH waves resonated when their frequencies corresponded to the eigenfrequencies of the crack. Finally, we theoretically showed that the resonant second HH waves were generated by local defect resonance and nonlinearity.

scholarly journals Research on Fatigue Damage in High-Strength Steel (FV520B) Using Nonlinear Ultrasonic Testing

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Bingbing Chen ◽  
Chao Wang ◽  
Pengfei Wang ◽  
Sanlong Zheng ◽  
Weiming Sun
Keyword(s):  
Fatigue Damage ◽  
High Strength Steel ◽  
Main Crack ◽  
Lamb Waves ◽  
High Strength ◽  
Nonlinear Parameter ◽  
Damage State ◽  
Nonlinear Parameters ◽  
Highly Sensitive ◽  
Nonlinear Ultrasonic

In view of the early fatigue damage of high-strength steel FV520B, a nonlinear ultrasonic detection was performed on two types of fatigue samples using nonlinear Lamb waves. The experimental results indicated that the ultrasonic nonlinear parameter is highly sensitive to early fatigue damage in high-strength FV520B. For plate specimens, the ultrasonic nonlinear parameter increased with the number of fatigue cycles. Scanning electron microscopy (SEM) observations of the fatigue specimens revealed that as the number of fatigue cycles increased, the microstructure of the material gradually deteriorated, and the ultrasonic nonlinear parameter increased. For notched specimens, the ultrasonic nonlinear parameter increased as the size of the main crack increased. SEM observations of the fracture indicated that the ultrasonic nonlinear parameters were more consistent with the equivalent microcrack length (defined as the sum of microcrack lengths in the statistical area), as compared with the length of the main crack. It was determined that the nonlinear effect of the Lamb wave is related to the equivalent microcrack length inside the material and that the ultrasonic nonlinear parameter can effectively characterize the fatigue damage state of high-strength FV520B.

Nonlinear Ultrasonic Method to Detect Micro-Delamination in Electronic Packaging

2005 ◽  
Vol 297-300 ◽  
pp. 813-818 ◽  
Author(s):  
Job Ha ◽  
Kyung Young Jhang
Keyword(s):  
Electronic Packaging ◽  
Ultrasonic Method ◽  
Frequency Component ◽  
Nonlinear Parameter ◽  
Crack Face ◽  
Test Tool ◽  
Nonlinear Ultrasonic ◽  
Parameter Dependent ◽  
Non Destructive ◽  
Nonlinear Ultrasonic Method

The linear ultrasonic technique has been extensively used as a powerful, non-destructive test tool for reliability testing and failure analysis of electronic packaging. This is used most often in the inspection of defects such as delaminations, voids, or cracks through use of a SAM (Scanning Acoustic Microscope). Then, as the reliability level that is required of electronic packaging becomes higher and the thickness of package becomes thinner, the possible defect which needs to be detected becomes smaller. In the conventional SAM, however it is very difficult to detect small defects less than m µ 1 . 0 , such as micro-delaminations. In order to solve such a problem, this paper proposes a nonlinear ultrasonic method, where the nonlinearity caused by the effect of crack-face interactions is considered. The basic concept of this method involves harmonic frequencies that are generated in the transmitted ultrasonic wave due to the partial contact at the interface of micro-delamination. As an evaluation index, the nonlinear parameter dependent on the amplitude of the second order harmonic frequency component is obtained by spectral analysis of the transmitted signal. Experimental results show that the nonlinear parameter has good correlation with the micro-gap and the proposed method can detect the micro-delamination even less than nm 1 .

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