Stress Evaluation Using Ultrasonic Interference Spectrum of Leaky Lamb Waves

Abstract

This paper presents a nondestructive stress evaluation technique using the ultrasonic interference spectrum of leaky Lamb waves. By using a specific pitch-catch ultrasonic setup, the symmetric and antisymmetric modes of Lamb waves in a finite plate are decoupled, leading to simple relationships between the modal frequency spacing of two adjacent modes in the interference spectrum and the acoustic wave velocities that are functions of stress. As a result, the stress in the plate can be determined by measuring the modal frequency spacing instead of the relative flight times to calculate the acoustic wave velocity. Extensive experiments were carried out to verify the viability and robustness of the new technique using a simple testing system. It has been demonstrated that the new technique is about 25 times more accurate than existing flight-time approaches using the same testing system. The experimental results agree well with the results obtained by other ultrasonic methods using expensive equipment.

Progress and Challenges of Ultrasonic Testing for Stress in Remanufacturing Laser Cladding Coating

“…The main methods for testing stress based on acoustoelasticity theory include the use of the relationship between ultrasonic velocity and stress [ 44 ]; ultrasonic attenuation degree and stress [ 45 ]; the incident angle of Rayleigh wave and stress [ 46 ]; echo power spectrum and stress [ 47 ]; and the interaction of acoustic beams and stress [ 48 ]. The excitation waveforms used to measure stress in laser cladding coating include Rayleigh waves [ 16 ], critical refraction longitudinal waves [ 49 ], or two wave combinations [ 50 ].…”

The influence of surface effects on the coupling vibration of bioliquid-filled microtubules

“…Here, in order to clearly describe the effect of bioliquid in MT on the coupling vibration frequency of the MT considering surface effects, only the term containing the mode function Y i corresponding to the vibration mode of the requested order is considered. Therefore, from equation (27), the coupling vibration frequency of bioliquid-filled MT considering surface effects is expressed as where ! 0 i represents the ith order of natural frequency of an individual MT without considering surface effects, which is as follows…”

“…26 The stress state between MT and cells can be evaluated by using ultrasonic interference spectrum of leaky lamb waves. 27 Because the bio-functions of MT are extremely sensitive to their vibration modes and frequencies, 28 many authors [29][30][31] studied the vibration characteristics of MT based on different physical models.…”

Contact Laser-Ultrasonic Evaluation of Residual Stress

“…One of the solutions of this problem is the application of the laser-ultrasonic technique [8]. In addition to improve the precision of time-offlight measurements, the authors of [9] have developed an alternative ultrasonic technique by using the modal frequency spacing (MFS) of leaky Lamb waves (LLW), in which a simple relationship has been derived to link the ultrasonic wave velocity and the MFS of two adjacent Lamb wave modes in the interference spectrum of LLW. Thus, the stress-induced changes of the velocity of ultrasonic waves can be evaluated by measuring the variation of MFS in the frequency domain.…”

“…Thus, the stress-induced changes of the velocity of ultrasonic waves can be evaluated by measuring the variation of MFS in the frequency domain. Compared with the existing time-of-flight approaches, the measurement of the MFS in the frequency domain is demonstrated to be sensitive to very small stress-induced changes of ultrasonic wave velocities in aluminum specimens [9].…”