scholarly journals Propagation characteristics of airborne ultrasonic waves in porous materials

2008 ◽  
Vol 29 (1) ◽  
pp. 82-85 ◽  
Author(s):  
Kenichi Aoki ◽  
Tomoo Kamakura
Keyword(s):  
Porous Materials ◽  
Ultrasonic Waves ◽  
Propagation Characteristics

Effects of Briquettes with Different Crack Structures on Propagation Characteristics of Ultrasonic Waves under Wetting Conditions

2020 ◽  
Author(s):  
Gang Wang ◽  
Jinzhou Li ◽  
Huaixing Li ◽  
Zhiyuan Liu ◽  
Yanpei Guo ◽  
...  
Keyword(s):  
Particle Size ◽  
Ultrasonic Velocity ◽  
Bituminous Coal ◽  
Ultrasonic Attenuation ◽  
Crack Size ◽  
Ultrasonic Waves ◽  
Ultrasonic Frequency ◽  
Propagation Characteristics ◽  
Sample Mass ◽  
Velocity Increase

Abstract In order to examine the effect of briquettes with different crack structures on ultrasonic characteristics under different wetting conditions, a series of ultrasonic testing are carried out on briquettes at different wetting heights and the ultrasonic characteristics in these coal samples are explored. The results show that ultrasonic amplitude is positively correlated with the emission voltage, whereas ultrasonic frequency is negatively correlated with the emission voltage. Changes in both are closely related to the particle size and density. The ultrasonic velocity is positively correlated with the wetting degree. Sample mass has the greatest effect on the ultrasonic velocity, followed by particle size, and pressure has the smallest effect. At dry stage, ultrasonic velocity in gas coal is less than that in bituminous coal. The opposite is true in the fully wet state. The influence of crack thickness on ultrasonic velocity gradually increases with the wetting degree increasing. At dry stage, the velocity gradually increases with the crack dip increasing, while as the wetting height increasing, magnitude of velocity increase gradually decreases with the dip increasing. The ultrasonic attenuation in the briquettes reduces with the emission voltage enhancing. The attenuation decreases with sample particle size, crack thickness and crack size decreasing and with sample mass, pressure and crack dip increasing. The ultrasonic attenuation shows a trend of increase before decrease with the wetting height increasing. The attenuation of ultrasonic wave increases with wave velocity increasing for intact samples and shows a trend of increase before decrease for cracked samples.

scholarly journals Ultrasonic Properties of Plastically Deformed Ice

1975 ◽  
Vol 15 (73) ◽  
pp. 161-169 ◽  
Author(s):  
J. Tatibouet ◽  
R. Vassoille ◽  
J. Perez
Keyword(s):  
Plastic Deformation ◽  
Physical Properties ◽  
Sound Velocity ◽  
Single Crystals ◽  
Stress Waves ◽  
Ultrasonic Waves ◽  
Velocity Of Sound ◽  
Propagation Characteristics ◽  
Ultrasonic Properties ◽  
Crystalline Materials

AbstractMany authors have used propagation of ultrasonic waves in ice for glaciological studies. This propagation is characterized by the velocity of sound and by the attenuation of stress waves. In crystalline materials, these two characteristics depend on structural slate. In particular plastic deformation gives velocity and attenuation variations.We have measured the sound velocity and attenuation of ultrasonic waves in strained specimens of ice (single crystals and polycrystals). These measurements done between 100 and 273 K at a frequency of 5 MHz show that plastic deformation leads to an increase of attenuation arid an increase of velocity. Annealing treatments at 271 K cause recovery of propagation characteristics. The variation in attenuation can be interpreted by the theory of dislocations and this interpretation is supported by our data on the influence of frequency on this increase of attenuation induced by plastic deformation, but the theory of dislocations implies a decrease of modulus, i.e. of velocity, hence we must postulate that an added phenomenon screens the effect of dislocations. That phenomenon could be connected with ageing effects observed on different physical properties of ire and may be due to modification of protonic arrangement or creation of interstitials during plastic deformation. Thus our experiments show that it is necessary to be careful in using results determined from the propagation of ultrasonic waves in ice.

On wave propagation characteristics in fluid saturated porous materials by a nonlocal Biot theory

2016 ◽  
Vol 379 ◽  
pp. 106-118 ◽  
Author(s):  
Lihong Tong ◽  
Yang Yu ◽  
Wentao Hu ◽  
Yufeng Shi ◽  
Changjie Xu
Keyword(s):  
Wave Propagation ◽  
Porous Materials ◽  
Biot Theory ◽  
Propagation Characteristics

Reflection and transmission at normal incidence onto air-saturated porous materials and direct measurements based on parametric demodulated ultrasonic waves

Ultrasonics ◽  
2006 ◽  
Vol 44 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Bernard Castagnède ◽  
Mohamed Saeid ◽  
Alexei Moussatov ◽  
Vitalyi Gusev ◽  
Vincent Tournat
Keyword(s):  
Porous Materials ◽  
Normal Incidence ◽  
Ultrasonic Waves ◽  
Reflection And Transmission ◽  
Direct Measurements

scholarly journals Assessment of the Structural Integrity of Timber Utility Poles Using Ultrasonic Waves

2021 ◽  
Keyword(s):  
Wave Propagation ◽  
Guided Waves ◽  
Structural Integrity ◽  
Numerical Data ◽  
Ultrasonic Waves ◽  
Propagation Characteristics ◽  
Utility Pole ◽  
Utility Poles ◽  
Non Destructive ◽  
Wave Modes

Abstract. In this study, guided stress waves were used to evaluate the conditions of a timber utility pole experimentally and numerically using COMSOL Multiphysics. Macro Fiber Composites (MFCs), due to their flexibility and convenience to install on curved surfaces, were used to actuate and sense guided waves along the tested specimens. Based on the wave propagation characteristics in these types of structures, an MFC actuator ring, which was developed in the previous work, was applied to tune and enhance the propagating wave modes of interest. The designed ring was used to excite longitudinal ultrasonic wave modes, mainly L(0,1), for the purpose of determining the embedded length of the pole. For the damage localization a single MFC excitation was used which proved to be more efficient than the actuator ring. Embedding the timber in soil had minimum impact on the wave propagation characteristics, given that the waves were confined in the timber pole with minimal leakage to the surrounding. The embedded length was determined accurately for sound and damage timber, using both experimental and numerical data with an error of less than 3 %. The deterioration in the timber structure, within the embedded region, was also evaluated with high accuracy of 93 %. Based on the obtained results, guided waves have high potential to be used as a non-destructive tool for the assessment and evaluation of timber utility poles.

A Study on Propagation Characteristics of Spread Spectrum Sound Waves Using a Band-Limited Ultrasonic Transducer

2004 ◽  
Vol 16 (3) ◽  
pp. 333-341 ◽  
Author(s):  
Akio Yamane ◽  
◽  
Taketoshi Iyota ◽  
Yongwoon Choi ◽  
Yuzuru Kubota ◽  
...  
Keyword(s):  
Spread Spectrum ◽  
Ultrasonic Transducer ◽  
Ultrasonic Waves ◽  
Sequence Length ◽  
High Signal ◽  
Propagation Characteristics ◽  
Positioning Systems ◽  
Signal Discrimination ◽  
Band Limited ◽  
Code Division Multiple

Propagation characteristics and range experiments of spread spectrum 40kHz ultrasonic waves have been explored under band-limited frequency. Comparative experiments were conducted using two arrangements combining a broadband speaker and a microphone for the broadband case, and an all-purpose receiving transducer and the broadband speaker for the band-limited case. Under the broadband condition, range accuracy measurements and evaluation of signal discrimination in a code division multiple transmission were made demonstrating 0.034% (corresponding to about 7mm in range distance) of range accuracy for a full-scale distance of 21.6m, demonstrating high signal discrimination. The severely band-limited experiment improved accuracy from 0.084% for a distance of 8.4m to 0.063% for a greater distance of 14.4m using a longer M-sequence length by extending shift registers from 10-bit to 15-bit. These experimental results show promise in the intended application of ultrasonic spread spectra to local positioning systems.

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