Due to the propagation and interaction characteristics in materials of the ultrasonic wave, it is widely used in the different fields such as medical, mechanical, and construction engineering, specially to detect cracks and defects in... more
Due to the propagation and interaction characteristics in materials of the ultrasonic wave, it is widely used in the different fields such as medical, mechanical, and construction engineering, specially to detect cracks and defects in concrete construction, and to identify characteristics of concrete material as well. Understanding the propagation and interaction characteristics of the ultrasound wave in isotropic and anisotropy elastic materials plays a very important role. The paper presents a method for a two-dimensional simulation of ultrasonic wave propagation in concrete structure treating as homogenous, isotropic and anisotropic elastic media. A mathematical model of wave propagation using dynamic equilibrium equations in concrete structures with inclusions, steel reinforcements and cracks, is introduced. Then, numerical simulation is mentioned based on finite element method. The results of simulation show two-dimensional images of wave propagation inside concrete structures, as well as displacements, stresses and strains at specific points in the material according to space and time. The simulations are made for different cases of concrete structures with inclusions, steel reinforcements and open cracks.
It has been a common practice to estimate the Unconfined Compressive strength (UCS) of rock through correlations that relate it to other index parameters such as the Brazilian Tensile Strength (BTS) and the Ultrasonic Pulse Velocity í... more
It has been a common practice to estimate the Unconfined Compressive strength (UCS) of rock through correlations that relate it to other index parameters such as the Brazilian Tensile Strength (BTS) and the Ultrasonic Pulse Velocity í µí± í µí± ; nonetheless, selecting the most appropriate equation to use has always been a challenge considering the heterogeneity of rocks and their variant behaviour. Therefore, the use of equations which are especially developed for certain rock type at a specific location is recommended. This paper suggests 3 equations to predict UCS from BTS, bulk density (í µí¼) and í µí± í µí± for marlstone of the Eastern Province of Saudi Arabia. 35 core samples are collected and tested in the laboratory for UCS, BTS and í µí± í µí±. Statistical analysis is performed on the experimental results, and subsequently 3 statistical models that relate BTS, í µí± í µí± , and rock bulk density í µí¼ to UCS are developed. Corrected correlation coefficients of the three models are found to be 0.575, 0.663, and 0.641, respectively. Additional reliable equation that relate the bulk density to í µí± í µí± is produced with a corrected correlation coefficient of 0.95.
In systems with rotational symmetry, bending modes occur in doubly-degenerate pairs with two independent vibration modes for each repeated natural frequency. In circular plates, the standing waves of two such degenerate bending modes can... more
In systems with rotational symmetry, bending modes occur in doubly-degenerate pairs with two independent vibration modes for each repeated natural frequency. In circular plates, the standing waves of two such degenerate bending modes can be superposed with a 1/4 period separation in time to yield a traveling wave response. This is the principle of a traveling wave ultrasonic motor (TWUM), in which a traveling bending wave in a stator drives the rotor through a friction contact. The stator contains teeth to increase the speed at the contact region, and these affect the rotational symmetry of the plate. When systems with rotational symmetry are modified either in their geometry, or by spatially varying their properties or boundary conditions, some mode-pairs split into singlet modes having distinct frequencies. In addition, coupling between some pairs of distinct unperturbed modes also causes quasi-degeneracies in the perturbed modes, which leads their frequency curves to approach and veer away in some regions of the parameter space. This paper discusses the effects of tooth geometry on the behavior of plate modes under free vibration. It investigates mode splitting and quasi-degeneracies and derives analytic expressions to predict these phenomena, using variational methods and a degenerate perturbation scheme for the solution to the plate’s discrete eigenvalue problem; these expressions are confirmed by solving the discrete eigenvalue problem of the plate with teeth.
Due to the propagation and interaction characteristics in materials of the ultrasonic wave, it is widely used in the different fields such as medical, mechanical, and construction engineering, specially to detect cracks and defects in... more
Due to the propagation and interaction characteristics in materials of the ultrasonic wave, it is widely used in the different fields such as medical, mechanical, and construction engineering, specially to detect cracks and defects in concrete construction, and to identify characteristics of concrete material as well. Understanding the propagation and interaction characteristics of the ultrasound wave in isotropic and anisotropy elastic materials plays a very important role. The paper presents a method for a two-dimensional simulation of ultrasonic wave propagation in concrete structure treating as homogenous, isotropic and anisotropic elastic media. A mathematical model of wave propagation using dynamic equilibrium equations in concrete structures with inclusions, steel reinforcements and cracks, is introduced. Then, numerical simulation is mentioned based on finite element method. The results of simulation show two-dimensional images of wave propagation inside concrete structures, as well as displacements, stresses and strains at specific points in the material according to space and time. The simulations are made for different cases of concrete structures with inclusions, steel reinforcements and open cracks
The paper reports the study of magnetic field induced structures in magnetic nanofluid investigated through ultrasonic wave propagation. Modified Tarapov’s theory is used to study variation in velocity anisotropy with magnetic field. The... more
The paper reports the study of magnetic field induced structures in magnetic nanofluid investigated through ultrasonic wave propagation. Modified Tarapov’s theory is used to study variation in velocity anisotropy with magnetic field. The types of field induced structures depend upon the chemical structure of the carrier in which magnetic nanoparticles are dispersed. Our study indicates formation of fractals and chain respectively, in transformer oil and kerosene based fluid. This difference is explained on the basis of particle–particle interaction and particle–medium interaction.
In this study, using Harfang Code 32 device, the slag catcher pipelines in one of the South Pars phases were tested. In radiography method of these lines, no clear defect was observed in radiographic films due to the high thickness of 40... more
In this study, using Harfang Code 32 device, the slag catcher pipelines in one of the South Pars phases were tested. In radiography method of these lines, no clear defect was observed in radiographic films due to the high thickness of 40 mm. However, marvelous results were obtained using advanced ultrasonic. Review and analysis of the results will result in high potential of three-dimensional ultrasonic method in identifying defects in pipelines with high thicknesses and preventing financial and life-threatening risks during the use of these refineries in the future.
An ultrasonic assembly device exhibiting broadband behavior and a sacrificial plastic frame is described. This device is used to assemble a variety of microscopic particles differing in size, shape, and material into simple patterns... more
An ultrasonic assembly device exhibiting broadband behavior and a sacrificial plastic frame is described. This device is used to assemble a variety of microscopic particles differing in size, shape, and material into simple patterns within several host fluids. When the host fluid is epoxy, the assembled materials can be cured and the composite sample extracted from the sacrificial frame. The wideband performance means that within a single device, the wavelength can be varied, leading to control of the length scale of the acoustic radiation force field. We show that glass fibers of 50 ??m length and 14 μm diameter can be assembled into a series of stripes separated by hundreds of microns in a time of 0.3 s. Finite element analysis is used to understand the attributes of the device which control its wideband characteristics. The bandwidth is shown to be governed by the damping produced by a combination of the plastic frame and the relatively large volume of the fluid particle mixture. The model also reveals that the acoustic radiation forces are a maximum near the substrate of the device, which is in agreement with experimental observations. The device is extended to 8-transducers and used to assemble more complex particle distributions.
We report on experiments on the effects of air bubbles on ultrasound velocity measurements in fluids. We used an acoustic Doppler velocimeter system for measuring the three velocity components in a single point and an acoustic... more
We report on experiments on the effects of air bubbles on ultrasound velocity measurements in fluids. We used an acoustic Doppler velocimeter system for measuring the three velocity components in a single point and an acoustic Doppler velocimetry profiler system for measuring axial velocity in several points along the beam. The results suggest that both systems essentially measure the velocity of the bubbles, independent of the low air-volume concentration and of bubble radii in the flow field.
It has been a common practice to estimate the Unconfined Compressive strength (UCS) of rock through correlations that relate it to other index parameters such as the Brazilian Tensile Strength (BTS) and the Ultrasonic Pulse Velocity í... more
It has been a common practice to estimate the Unconfined Compressive strength (UCS) of rock through correlations that relate it to other index parameters such as the Brazilian Tensile Strength (BTS) and the Ultrasonic Pulse Velocity í µí± í µí± ; nonetheless, selecting the most appropriate equation to use has always been a challenge considering the heterogeneity of rocks and their variant behaviour. Therefore, the use of equations which are especially developed for certain rock type at a specific location is recommended. This paper suggests 3 equations to predict UCS from BTS, bulk density (í µí¼) and í µí± í µí± for marlstone of the Eastern Province of Saudi Arabia. 35 core samples are collected and tested in the laboratory for UCS, BTS and í µí± í µí±. Statistical analysis is performed on the experimental results, and subsequently 3 statistical models that relate BTS, í µí± í µí± , and rock bulk density í µí¼ to UCS are developed. Corrected correlation coefficients of th...
Active materials are investigated as a tuning possibility for phononic crystals. Electromechanical properties of piezoelectric materials electrical and mechanical variables are coupled. Thus, the propagation properties of elastic waves... more
Active materials are investigated as a tuning possibility for phononic crystals. Electromechanical properties of piezoelectric
materials electrical and mechanical variables are coupled. Thus, the propagation properties of elastic waves can be tuned using
electrical impedance load connected to the piezoelectric layer. In this study, a theoretical one-dimensional model is proposed to calculate the electrical impedance of an active layer located inside a finite periodic structure including both piezoelectric and passive layers. Depending on the electrical impedance load, various effects on the position and the amplitude of the electrical resonance are observed in very good agreement, between experimental and theoretical results.
