Experimental evaluation of the true intrinsic nonlinearity of rail steel using Rayleigh waves and a new nonlinearity parameter

2020 ◽  
Author(s):  
Faeez Masurkar ◽  
Peter Tse
Keyword(s):  
Experimental Evaluation ◽  
Rayleigh Waves ◽  
Rail Steel ◽  
Nonlinearity Parameter ◽  
Intrinsic Nonlinearity

Interrogating the health condition of rails using the narrowband Rayleigh waves emitted by an innovative design of non-contact laser transduction system

2020 ◽  
pp. 147592172096760
Author(s):  
Faeez Masurkar ◽  
Kim Ming Ng ◽  
Peter W Tse ◽  
Nitesh P Yelve
Keyword(s):  
Health Status ◽  
Optical System ◽  
Rayleigh Waves ◽  
Rail Steel ◽  
Second Harmonic ◽  
Laser Doppler Vibrometer ◽  
Health Condition ◽  
Innovative Design ◽  
Scanning Laser Doppler Vibrometer ◽  
Contact Experiment

The article reports an innovative optical system that is designed to interrogate the health condition of macroscopically intact rail specimens by measuring its inherent nonlinearity using the narrowband Rayleigh waves. A line-arrayed pattern is developed through the optical system that generates narrowband Rayleigh waves with high power on the surface of the rail. As a result of lattice-anharmonicity, a second harmonic is produced in the wave that is sensed by a scanning laser Doppler vibrometer. The spectral amplitudes of the first and generated second harmonics are used to calculate the inherent nonlinearity using an amplitude-based nonlinearity equation. These measurements are carried out on the head, web, and foot of the rail. The performance of the non-contact experiment is also compared with that of a contact experiment carried out using wedge transducers. The experimentally evaluated nonlinearity of the rail steel is further compared with that obtained using a physics-based nonlinearity equation that relies on the higher-order elastic constants. Agreement of the results shows that the new optical system is effective in generating Rayleigh waves in rails and thereby measuring the inherent nonlinearity of the rail track. The estimation of inherent nonlinearity may help in diagnosing the health status of the macroscopically intact rail specimens in terms of their microstructural consistency and level of dissolved impurities before fixing them on a track.

scholarly journals Surface Roughness Effects on Self-Interacting and Mutually Interacting Rayleigh Waves

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5495
Author(s):  
Chaitanya Bakre ◽  
Cliff J. Lissenden
Keyword(s):  
Surface Roughness ◽  
Rayleigh Waves ◽  
Second Harmonic ◽  
Material Nonlinearity ◽  
Nonlinearity Parameter ◽  
Roughness Effects ◽  
Sinusoidal Waveform ◽  
Quantitative Understanding ◽  
Relative Nonlinearity ◽  
Attenuation And Dispersion

Rayleigh waves are very useful for ultrasonic nondestructive evaluation of structural and mechanical components. Nonlinear Rayleigh waves have unique sensitivity to the early stages of material degradation because material nonlinearity causes distortion of the waveforms. The self-interaction of a sinusoidal waveform causes second harmonic generation, while the mutual interaction of waves creates disturbances at the sum and difference frequencies that can potentially be detected with minimal interaction with the nonlinearities in the sensing system. While the effect of surface roughness on attenuation and dispersion is well documented, its effects on the nonlinear aspects of Rayleigh wave propagation have not been investigated. Therefore, Rayleigh waves are sent along aluminum surfaces having small, but different, surface roughness values. The relative nonlinearity parameter increased significantly with surface roughness (average asperity heights 0.027–3.992 μm and Rayleigh wavelengths 0.29–1.9 mm). The relative nonlinearity parameter should be decreased by the presence of attenuation, but here it actually increased with roughness (which increases the attenuation). Thus, an attenuation-based correction was unsuccessful. Since the distortion from material nonlinearity and surface roughness occur over the same surface, it is necessary to make material nonlinearity measurements over surfaces having the same roughness or in the future develop a quantitative understanding of the roughness effect on wave distortion.

Experimental Evaluation of the Dermoskeleton Concept: Addressing the Soldiers Overload Challenge

2012 ◽  
Author(s):  
Chris Ste-Croix ◽  
David Tack ◽  
Denis Boucher ◽  
Francois Ruel ◽  
Gilles Pageau ◽  
...  
Keyword(s):  
Experimental Evaluation
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