Ultrasonic Wave Measurements Research Articles

Correlation between Voids Ratio and Characteristic Responses to Ultrasonic Pulses Through Sandy Soils

The microporous structure of granular soils that provides important information such as shear strength, compressibility, and hydraulic conductivity, is directly influenced by the void ratio. Therefore, a quick identification of the void ratio, by a non-destructively way and in situ becomes an interesting practice. Ultrasound has been successfully used for ceramic materials, wood, concrete and rocks. When dealing with soils, great efforts are made to understand its behavior and characteristics through wave propagation velocity. However, does still have a lack of discussions about the ultrasonic wave properties. In this paper, a study analysing 156 saturated samples of sands by ultrasound for 3 median particle size, with void ratio ranging from 0.5 to 1.1. The ultrasonic wave measurement was performed using the transmit and receiveand technique, with 50 kHz transducers. The study demonstrates a possibility of identifying transition zones between sample’s materials composition. Considering the same dominant medium, a correlation was observed among the void ratio and the maximum amplitude, the damping coefficient, dominant frequency and ultrasonic pulse speed. There is also the identification of characteristic frequencies for these media. Therefore, the novelties of the present study are mainly the development of a feasible technique to investigate void ratio of granular saturated soils using direct measurements of the ultrasonic wave characteristics.

Ultrasonic velocity, attenuation, and mechanical behavior of Longmaxi bedded shale under uniaxial compressive tests

Knowledge of ultrasonic wave velocity and attenuation related with bedding orientations plays an important role for successful downhole, hydraulic fracturing, and surface seismic data interpretation. Real-time ultrasonic wave measurements in load direction have been conducted on Longmaxi shale specimens during compressive fractured process in this study. The relations between mechanical properties and ultrasonic response of shale with various bedding angles are investigated. The P- and S-wave velocities increase with increasing stress to the peak strength, which can be ascribed to the closure of microcracks and pores perpendicular to the wave propagation direction. And then they decrease with sudden fall of stress at the post-peak stage that is controlled by the coalescence of newly generated microcracks to macroscopic fractures. The P-wave velocity is more sensitive to the bedding angles and axial stress than S-wave velocity. The axial stress weakens the velocity anisotropy of shale. The P-wave attenuations decrease (quality factor values increase) for 0°, 15°, and 30° shale specimens under pressure, whereas the first increment and then less variation occur for 45°, 60°, 75°, and 90° specimens. The difference may be caused by the bedding scattering that is more pronounced when the beddings are more inclined and perpendicular with respect to the wave propagation direction. The P-wave quality factor has a close relationship with the peak strength for each inclination specimen. What’ s more, the failure modes have been illustrated based on the wave velocity and attenuation anisotropy.

The influence of PbO and Bi2O3 on the radiation shielding and elastic features for different glasses

The radiation shielding effects and elastic properties of adding lead (Pb) and bismuth (Bi) to glasses was analyzed. Six different glasses, coded as G1-G6, were simulated with varying compositions of bismuth oxide and lead oxide, with G1 having the lowest density and G6 having the greatest. MCNP-5 code was used to calculate the mass attenuation coefficient, half value layer, tenth value layer, and mean free path of the glasses, the latter of which was compared with other radiation shields. These parameters were investigated between 0.015MeV and 15MeV. The bond compression model was utilized to analyze various parameters that describe the elastic properties of the glass samples. From the ultrasonic wave measurement result, the substitution of PbO and Bi2O3 which working as a network modifier towards SiO2 glass systems would break up the Si–O–Si bonds along with all the formation of non-bridging oxygen's which give the impact in the elastic moduli analysis of the glasses.

Ultrasonic and artificial intelligence approach: Elastic behavior on the influences of ZnO in tellurite glass systems

Raise in the industrial development field required some simulation in order to predict the glass characterization before the pure materials of oxide are melted. This study uses artificial neural networks (ANN) model as a tool to simulate the elastic properties of the binary series ZnO-TeO2 glasses. This simulation would predict the density and elastic modulus variation include microhardness and Poisson’s ratio. The result from the ANN model was found to give an excellent good agreement with those experimental works of binary series xZnO-(100-x)TeO2 (x = 0, 5, 10, 15, 20, 25, 30 mol%) glass systems. From the ultrasonic wave measurement result, the substitution of ZnO which working as a network modifier towards TeO2 glass systems would break up the Te-O-Te bonds of TeO4 into the form TeO3 along with all the formation of NBO’s which give the impact in the elastic moduli analysis.

Nondestructive Testing Ultrasonic Technique for Localization of Areas Subjected to Creep Deformation on In-Service Pipings Manufactured From Low-Alloyed Steel

Abstract Creep failure of the pressure equipment operated at high temperatures in power and petrochemical industry is a frequent reason of its collapse. Ultrasonic waves' velocity is sensitive to change of material properties due to thermally induced degradation processes, especially plastic strain. The article demonstrates that measurement of ultrasonic waves' velocity ratio is able to localize plastic strain induced by various means including creep. Results are confirmed by comparison with hardness and metallographic analysis. Furthermore, statistical significance of the results is tested by t-statistics. The proposed application may help with selection of potentially critical areas during routine inspections on pressure equipment in operation.

Viscoelastic properties of fused filament fabrication parts

Parts made by fused filament fabrication differ in their mechanical properties from the parent material. To investigate the effect of the manufacturing process on the mechanical properties of 3D-printed parts, a series of experiments including Dynamic Mechanical Analysis (DMA) and ultrasonic wave propagation were conducted. For this purpose, printed parts were made from custom ABS filament and were printed using a rectangular bead shape to minimize porosity. The main properties investigated included the elastic, loss and storage moduli, and the material loss tangent (tan δ). Results indicate that the elastic modulus of the printed material was somewhat lower than that of the parent material, about 2 GPa for frequencies 0.1 Hz–100 Hz. Furthermore, tan δ was largest for the parent material at about 0.03 compared with 0.01–0.02 for the printed material. Ultrasonic longitudinal wave measurements at 1 MHz on printed specimens with bead angles of 0°, 45° and 90°, revealed minimal anisotropy and, consistent with DMA results, tan δ was also largest for the parent material.

Swept-frequency ultrasonic phase evaluation of adhesive bonding in tri-layer structures.

As modern aerospace and automotive designs continually strive for higher performance, and thus rely on advanced composite structures where adhesive bonding is a preferred method of joining, the need for a robust quantitative nondestructive bond strength measurement method has increased. As such, advanced nondestructive evaluation methods have been researched for increased sensitivity to weak interfacial bonding and ultimately to detect "kissing" bonds. In this work, a phase-based method for interrogating bonded joints and detecting weak adhesion is developed by using swept-frequency phase measurements of ultrasonic waves reflected from an adhesive joint and modeling adhesive interfaces as a distributed spring system. The method's sensitivity to bond strength is explored by ultrasonic phase evaluation of tri-layer joints with bond quality varied by controlling ultraviolet light exposure and extracting interfacial stiffness constants of the bonds. Mechanical tensile tests found each joint failed adhesively, allowing a linear correlation to be drawn between interfacial stiffness and tensile strength, consistent with previous theoretical research. The ultrasonic phase measurement method identifies intermediate bond strengths, rather than simply detecting good or bad bonds. This technique has the potential for the verification of bond quality in lightweight aerospace and automotive designs utilizing advanced composite structures with adhesive attachments.

Bat biosonar study using spatial audio techniques

Bats have highly specialized hearing adaptations that give them target detection, localization, and interception abilities that far surpass any man-made SONAR. There is a large body of research that has studied and attempted to mimic this remarkable natural sonar system using various methodologies. In many studies, multiple microphones and time difference of arrival were used for bat ultrasonic wave measurements. In this work, a new method using spatial audio techniques is introduced for bat biosonar measurements and analyses. A custom-built tetrahedral soundfield microphone that captures high-frequency sound up to 80 kHz from all directions was developed to acquire bat ultrasonic echoes in Ambisonic B-format. The recorded sound was processed using the HARPEx (High Angular Resolution Planewave Expansion) technique that decodes the 1st order spherical harmonics of the soundfield at the microphone into two plane waves in each time-frequency bin. The use of the soundfield microphone and associated processing provides new tools for analysis of bat echoes from the perspective of the bat. This talk will present details of the hardware and software development along with experimental validation results.

The effect of salt crystallization on degradation of volcanic building stones by sodium sulfates and sodium chlorides

Volcanic rocks cropping out in the north-northeast of Afyonkarahisar (Turkey) are extensively used as building stones for the construction of historical buildings with structural and architectonic purposes. Three building stones, including two tuffs and an andesite, were examined in the current research. The scope of this article was to study the decay mechanisms of these porous building stones by salt. For this purpose, laboratory studies were carried out in two stages. First, the main characterization analysis of the tested building stones was performed. The main technical values and parameters such as mineralogical–petrographic (polarizing microscope, XRD and SEM), chemical (XRF) and mechanical–physical properties were studied. Moreover, this study also included pore size distribution and capillary water absorption of the building stones, while their durability was investigated by means of salt crystallization tests according to TS EN 12370. Weathering tests were carried out by applying immersion–drying cycles with water containing sodium sulfate or sodium chloride. The structural changes of the building stones after the salt crystallization tests were investigated by SEM observations and ultrasonic wave measurements, while the strength properties were determined by uniaxial compressive strength tests. The highest values of dry weight loss were observed in the Ayazini tuff sample and andesite whereas the Seydiler tuff had the lowest value. The uniaxial compressive strength was 16.37% lower in the weathered samples (sodium sulfate test) compared to the fresh samples of andesite. As a result, only the Ayazini tuff was not durable and deteriorated in the environment containing sodium sulfate.

A New Technique for Characterization of Low Impedance Materials at Acoustic Frequencies

Measuring the mechanical properties of low impedance rubbery polymers at acoustic frequencies is a challenging problem due to the small signal amplitudes, relatively high loss, and the long wavelength of stress waves. One such material is solid polyurea (PU), an elastomeric copolymer, which has excellent chemical, thermal, and mechanical properties and is widely used as a coating (e.g. in truck bed lining) or blast protection (advanced helmet designs and concrete structures) material. Moreover, due to its heterogeneous structure, PU has a wide transition of thermo-mechanical behavior from rubber-like to glassy compared to most engineering polymers, which translates to a broader loss spectrum in frequency domain. In this study, we have developed a new test technique by modifying the split Hopkinson pressure bar and using ball impact to measure Young’s storage and loss moduli of polyurea at kHz frequencies. This will therefore fill the frequency gap between the dynamic mechanical analysis (DMA) and ultrasonic (US) wave measurement. The measured Young’s storage and loss moduli from this technique are compared with the master curves of the moduli developed using experimental data of dynamic mechanical analysis and ultrasonic wave measurements. This technique is a direct measurement which provides more reliable data in the kHz frequency range and can be used to evaluate the reliability of other indirect estimations including master curves. The utility of this technique is not limited to polyurea and it can be used to characterize other low impedance materials at kHz frequencies.

Determination of the Internal Damage of Purple Sweet Potatoes Non-Destructively Using Ultrasonic Wave Characteristics

This study aimed to analyze the ultrasonic wave characterization of Ayamurasaki purple sweet potatoes to predict the internal damage caused by weevil attack non-destructively. Sixty of health and 45 of infected purple sweet potatoes from farmers in Ciampea, Bogor were used for the experiment. Sample divided into 2 groups, the first group of 2/3 part was used in developing the model, and the second group of 1/3 part was used for validation. Ultrasonic wave characterization of purple sweet potatoes that harvested was tested using ultrasonic wave measurement apparatus with 50 KHz frequency. The result shows that the average wave velocity of infected purple sweet potatoes was 247.32 ms-1 and Mo value was 19.45, while the wave velocity of healthy purple sweet potatoes was 235.15 ms-1 and Mo value was 18.72. The average attenuation coefficient of infected purple sweet potatoes was 40.06 Np/m, while in health purple sweet potatoes was 42.69 Np/m. The result of discriminant analysis obtained a linear discriminant model that can distinctly separate between health and infected purple sweet potatoes. Accuracy of this grouping was high enough, around 85.71% so that the discriminant function can be used for grouping the health and infected purple sweet potatoes

Ultrasonic investigation of granular materials subjected to compression and crushing

Ultrasonic wave propagation measurement has been used as a suitable technique for studying the granular materials and investigating the soil fabric structure, the grain contact stiffness, frictional strength, and inter-particle contact area. Previous studies have focused on the variations of shear and compressional wave velocities with effective stress and void ratio, and lesser effort has been made in understanding the variation of amplitude and dominant frequency of transmitted compressional waves with deformation of soil packing. In this study, continuous compressional wave transmission measurements during compaction of unconsolidated quartz sand are used to investigate the impact of soil layer deformation on ultrasonic wave properties. The test setup consisted of a loading machine to apply constant loading rate to a sand layer (granular quartz) of 6 mm thickness compressed between two forcing blocks, and an ultrasonic wave measurement system to continuously monitor the soil layer during compression up to 48 MPa normal stress. The variations in compressional wave attributes such as wave velocity, transmitted amplitude, and dominant frequency were studied as a function of the applied normal stress and the measured normal strain as well as void ratio and particle size. An increasing trend was observed for P-wave velocity, transmitted amplitude and dominant frequency with normal stress. In specimen with the largest particle size (D50 = 0.32 mm), the wave velocity, amplitude and dominant frequency were found to increase about 230%, 4700% and 320% as the normal stress reached the value of 48 MPa. The absolute values of transmitted wave amplitude and dominant frequency were greater for specimens with smaller particle sizes while the normalized values indicate an opposite trend. The changes in the transmitted amplitude were linked to the changes in the true contact area between the particles with a transitional point in the slope of normalized amplitude, coinciding with the yield stress of the granular soil layer. The amount of grain crushing as a result of increase in the normal stress was experimentally measured and a linear correlation was found between the degree of grain crushing and the changes in the normalized dominant frequency of compressional waves.

Ultrasonic Bulk Waves Measurements for Defect Detection of Composite Materials

The defect detection in composite material is important for its quality control where the hidden defect such as crack, corrosion, notch, holes, void and porosity can develop. In this paper, the ultrasonic bulk wave measurements of longitudinal and shear waves are used to identify defect in the multilayered composite material. This study employs pulse echo technique and utilized angle beam transducer. The composite material model investigated in this contribution are made of 24 mm and 12 mm thick Aluminium plates with a width of 100 mm and a length of 203 mm which are separated with an approximately 1 mm thick oil layer. A simulated defect is created in the composite test material by drilling a hole with 2.5 mm diameter and 3 mm depth on the bottom surface of the third layer material. Finding indicates that the defect is located at 53.39 mm from transducer and the percentage difference of the defect location compared to the calculation method is 7%. It indicates that the proposed method can be use to detect defect in multilayered composite material within 10% accuracy compared to the calculation method.

Mechanical response of titanium tri-aluminide intermetallic alloy

The bulk titanium tri-aluminide intermetallic alloy was fabricated via foil reactive sintering using Ti and Al foils in the vacuum. Scanning electron microscopy (SEM) results demonstrated that the original Ti and Al foils were fully reacted and the only synthesized product is monolithic intermetallic Al3Ti. The basic physical properties of the fabricated intermetallic, such as Young's modulus and Poisson ratio, were determined using an ultrasonic wave measurement technique, and the compressive mechanical responses under both quasi-static and high strain rates were studied using universal load frame and modified split Hopkinson pressure bar system, respectively. The experimental results indicated that intermetallic Al3Ti exhibits brittle features, and its compressive strength was sensitive to strain rate. Moreover, the strain rate hardening behavior under high rate range is stronger than that under quasi-static deformation conditions.

Degradation in concrete structures due to cyclic loading and its effect on transport processes—Experiments and modeling

According to the objectives of the research group 1498, this paper deals with degradation effects in concrete structures that are caused by cyclic flexural loading. The goal is to determine their influence on the fluid transport processes within the material on the basis of experimental results and numerical simulations. The overall question was, to which extent the ingress of externally supplied alkalis and subsequently an alkali‐silica reaction are affected by such modifications in the microstructure. Degradation in the concrete microstructure is characterized by ultrasonic wave measurements as well as by microscopic crack analysis. Furthermore, experiments on the penetration behavior of water into the investigated materials were performed. The penetration behavior into predamaged concrete microstructures was examined by the classical Karsten tube experiment, nuclear magnetic resonance method, and time domain reflectometry techniques. In order to create an appropriate model of the material's degradation on the water transport, the Darcy law was applied to describe the flow in partially saturated concrete. Material degradation is taken into account by an effective permeability that is dependent on the state of degradation. This effective permeability is obtained by the micromechanical homogenisation of the flow in an Representative Elementary Volume (REV) with distributed ellipsoidal microcracks embedded in a porous medium. The data gained in the microscopic crack analysis is used as input for the micromechanical model. Finite element simulations for unsaturated flow using the micromechanical model were compared with the experimental results showing good qualitative and quantitative agreement.

Detecting damage events in concrete using diffuse ultrasound structural health monitoring during strong environmental variations

Diffuse ultrasonic wave measurements used in structural health monitoring applications can detect damage in concrete. However, the accuracy is very susceptible to environmental variations. In this study, a large concrete floor slab was monitored using diffuse wave fields that were generated by continuous-wave transmissions between ultrasonic transducers. The slab was monitored for several weeks while being subjected to changes in environmental conditions. Subsequently, it was damaged using impact hits, resulting in centimeter-scale cracking. The variations caused by the environment masked the effects of the damage in the measurements. To address this issue, the Mahalanobis distance was used to distinguish between the influence of the damage and the influence of the environmental variations. The Mahalanobis model uses amplitude and phase measurements of continuous waves at a set of different frequencies as inputs. A moving window approach was applied to the baseline data set to account for slow trends. This study shows that this technique greatly suppresses most of the variations caused by environmental conditions. All damage events in our data set have been detected.

Age and Sex Effects on the Active Stiffness of Vastus Intermedius under Isometric Contraction

Previously, a novel technique was proposed to quantify the relationship between the muscle stiffness and its nonfatigue contraction intensity. The method extended the measured range of isometric contraction to 100% maximum voluntary contraction (MVC) using an ultrasonic shear wave measurement setup. Yet, it has not been revealed how this relationship could be affected by factors like age or sex. To clarify these questions, vastus intermedius (VI) stiffness of 40 healthy subjects was assessed under 11 step levels of isometric contraction. The subjects were divided into four groups: young males, young females, elderly males, and elderly females (n = 10 for each). In a relaxed state, no significant difference was observed between the male and female subjects (p = 0.156) nor between the young and elderly subjects (p = 0.221). However, when performing isometric contraction, the VI stiffness of males was found to be significantly higher than that of females at the same level (p < 0.001), and that of the young was higher than the elderly (p < 0.001). Meanwhile, for two knee joint angles used, the stiffness measured at a 90° knee joint angle was always significantly larger than that measured at 60° (p < 0.001). Recognizing the active muscle stiffness of VI contributes to body stability, and these results may provide insight into the age and sex bias in musculoskeletal studies, such as those on fall risks.

A contactless ultrasonic surface wave approach to characterize distributed cracking damage in concrete

We describe an approach that utilizes ultrasonic surface wave backscatter measurements to characterize the volume content of relatively small distributed defects (microcrack networks) in concrete. A simplified weak scattering model is used to demonstrate that the scattered wave field projected in the direction of the surface wave propagation is relatively insensitive to scatterers that are smaller than the propagating wavelength, while the scattered field projected in the opposite direction is more sensitive to sub-wavelength scatterers. Distributed microcracks in the concrete serve as the small scatterers that interact with a propagating surface wave. Data from a finite element simulation were used to demonstrate the viability of the proposed approach, and also to optimize a testing configuration to collect data. Simulations were validated through experimental measurements of ultrasonic backscattered surface waves from test samples of concrete constructed with different concentrations of fiber filler (0.0, 0.3 and 0.6%) to mimic increasing microcrack volume density and then samples with actual cracking induced by controlled thermal cycles. A surface wave was induced in the concrete samples by a 50kHz ultrasonic source operating 10mm above the surface at an angle of incidence of 9°. Silicon-based miniature MEMS acoustic sensors located a few millimeters above the concrete surface both behind and in front of the sender were used to detect leaky ultrasonic surface waves emanating from concrete. A normalized backscattered energy parameter was calculated from the signals. Statistically significant differences in the normalized backscattered energy were observed between concrete samples with varying levels of simulated and actual cracking damage volume.

Experimental Investigation of Propagation and Transmission of Compressional Stress Waves in Cemented Paste Backfill

AbstractA split Hopkinson pressure bar (SHPB) was used to characterize the propagation of high intensity large strain compressional waves through cemented paste backfill (CPB). The effects of curing age, cement content, and degree of saturation on stress refraction at interfaces, velocity of propagation, and internal damping in CPB were investigated. The results show that a smaller portion of the incident stress wave is refracted at the CPB interface in unsaturated specimens in comparison to those in a near fully saturated condition. Increased refraction ratios and velocities of propagation as a result of increased curing age and cement content were mainly observed in unsaturated specimens. In addition, the effects of degree of saturation on stress wave propagation in unsaturated material seemed negligible. The compression wave propagation velocity in the SHPB was also compared with small strain velocities found by means of ultrasonic wave measurements. The measured small strain wave velocities were found...

Dynamic properties of polyurea-milled glass composites Part I: Experimental characterization

Polyurea (PU) is an elastomer, which exhibits unique thermo-mechanical properties. It is synthesized from a di-functional amine, e.g. Versalink P-1000 and a diisocyanate, e.g. Isonate143L. In this study, various volume fractions milled glass (MG) was added to create polyuria-milled glass composites (PU-MG). Milled glass is a micro fiber with cylindrical shape. The distribution of the milled glass in the polyurea matrix was observed under the scanning electron microscope. The dynamic properties of pure polyurea and the PU-MG composites were measured by dynamic mechanical analysis (DMA) in the low frequency range (1–20 Hz) and by ultrasonic wave measurement in the high frequency range (0.5–1.5 MHz). Both experiments show that increasing the milled glass volume fraction drastically increases both the storage and loss moduli of the composites. DMA results show that dynamic Young’s modulus increases with increasing frequency. However, longitudinal and shear moduli from ultrasonic wave measurement appears to be insensitive to frequency within the range of 0.5–1.5 MHz. The experimental dynamic moduli master curves of PU and PU-MG composites were constructed and compared. The relaxation function or creep compliance are generally useful than dynamic moduli for modeling of material response under complex histories. It is of practical use to convert dynamic mechanical data from the frequency domain into the time domain. The discrete relaxation spectra of the composites were calculated by fitting Prony series to the master curves, using least square nonlinear regression. Retardation spectra were then calculated using the interrelation between relaxation modulus and creep compliance in Laplace domain. Finally, the time domain relaxation modulus and creep compliance for each composite were obtained from the two spectra. In order to extend our understanding of the dynamic behavior of the PU-MG composite, micromechanical models have been created and are discussed in the accompanying paper Nantasetphong (2016a).