Ultrasonic Attenuation Research Articles

A Hybrid Strategy Two‐Dimensional Concrete Aggregate Filling Algorithm

ABSTRACTAccurate and highly efficient construction of numerical concrete models with different gradations is important to analyze the acoustic properties of ultrasonic waves in concrete. The random aggregates‐based method is a classic approach to meso‐structural modeling of concrete and is particularly suitable for generating models with low‐density aggregates. However, when facing the simulation requirements of concrete models with large volumes, small particle sizes, and high aggregate content, traditional random aggregates‐based methods encounter challenges in satisfying aggregate packing density and modeling efficiency. In order to improve the efficiency of aggregate placement in modeling concrete meso‐models, we proposed a hybrid‐strategy point cloud placement algorithm that combines the re‐placement and sedimentation strategies. Then, the algorithm's effectiveness in improving the modeling efficiency is verified by reconstruction experiments on random aggregate models with different aggregate grades. Finally, the model's reliability and validity is further confirmed by simulation analysis of the ultrasonic attenuation characteristics of the model. The results show that the algorithm can rapidly generate more than 75% aggregate packing density concrete specimens and significantly outperforms similar algorithms regarding aggregate placement efficiency and model generation time. In addition, the model generated by the proposed algorithm can accurately simulate the attenuation characteristics of ultrasonic waves in concrete.

Study of mechanical and thermophysical properties of Ni3Ti

Abstract This research assesses the thermophysical and ultrasonic characteristics of the intermetallic compound Ni3Ti, which has a hexagonal crystalline structure. The selected material exhibits many noteworthy characteristics, including the shape memory effect, a high melting point, extremely elastic qualities, etc. The Lennard-Jones potential model has been used to calculate the higher-order elastic constants. The mechanical properties of the material, which provide details regarding its stability and intrinsic qualities, are computed using the second-order elastic constants. Additionally, we have computed the thermal conductivity at 300 K, specific heat, ultrasonic velocities, and Debye temperature. Ultimately, the ultrasonic attenuation is determined using all of the available parameters. The obtained results agree with the data available in the literature.

Physical and mechanical properties of concrete containing plastic tube fibers

Plastic tube fibers (PTFs) are one form of plastic waste resulting from the production of plastic mats that end up in the landfill. Until today, no attempt has been made to explore the applicability of PTFs as a construction material for a circular economy. This paper investigates the applicability of PTFs as fibers in fiber-reinforced concrete (FRC) production. A series of tests are carried out to investigate the effects of volume fractions (VFs) and the length of the fibers on the physical and mechanical properties of FRC-containing PTFs. The effects of the length and VFs on the unit weight, compressive strength, flexural strength, tensile strength, pulse velocity, thermal conductivity, and microstructure of FRC are examined. Three different lengths of fibers of 20 mm, 30 mm, and 50 mm, and VFs of PTFs of 0 %, 0.5 %, 1 %, and 1.5 % are studied. Results show that although the mechanical properties of concrete decrease as the VFs increase from 0 % to 1.5 %, the rate of reduction becomes smaller as the length of the fiber becomes larger. The maximum reduction of compressive, tensile, and flexural strength was found to be as high as 35 %, 25 %, and 35 % compared to the control sample obtained for 20 mm fiber length having 1.5 % VFs. Formulas to predict the tensile and flexural strengths of concrete containing PTFs as a function of the compressive strength are proposed and found to be providing satisfactory results. From a microscopic view, it is seen that the sample containing higher VFs shows less density and homogeneity of concrete which leads to an increase in the micropores of the concrete. Furthermore, the ultrasonic pulse velocity and attenuation coefficient decrease as the VFs of PTFs increase.

Enhancing ultrasonic attenuation images through multi-frequency coupling with total nuclear variation.

Quantitative ultrasound is a non-invasive image modality that numerically characterizes tissues for medical diagnosis using acoustical parameters, such as the attenuation coefficient slope. A previous study introduced the total variation spectral log difference (TVSLD) method, which denoises spectral log ratios on a single-channel basis without inter-channel coupling. Therefore, this work proposes a multi-frequency joint framework by coupling information across frequency channels exploiting structural similarities among the spectral ratios to increase the quality of the attenuation images. A modification based on the total nuclear variation (TNV) was considered. Metrics were compared to the TVSLD method with simulated and experimental phantoms and two samples of fibroadenoma in vivo breast tissue. The TNV demonstrated superior performance, yielding enhanced attenuation coefficient slope maps with fewer artifacts at boundaries and a stable error. In terms of the contrast-to-noise ratio enhancement, the TNV approach obtained an average percentage improvement of 34% in simulation, 38% in the experimental phantom, and 89% in two in vivo breast tissue samples compared to TVSLD, showing potential to enhance visual clarity and depiction of attenuation images.

Investigation of structural, ultrasonic, and radiation shielding properties of PbO-B2O3 glasses reinforced MnO2

Glass composition systems of (65-x) B2O3+15 PbO +15 Na2O+ 5 Al2O3+ x MnO2, where x = 0, 0.1, 0.3 and 0.5 mol% were organized by the usual melting-annealing process. Electron spin resonance (ESR) displayed broad hyperfine before and after exposing glasses to 25 kGy of gamma radiation, while sharp ESR signals at magnetic field range 3200–3500 Gauss were detected after irradiating glasses with 50 kGy. FTIR and Raman spectroscopy displayed the high structural stability of the glasses towards 25 kGy of gamma radiation, signifying the central building units of various borate groups at the same intensities and positions. Different ultrasonic characteristics such as ultrasonic velocities, elastic properties, Poisson’s ratio, Lamé constants, acoustic impedance, and ultrasonic attenuation coefficient didn’t variate greatly with gamma radiation exposure to 25 kGy. Comparing results showed that 0.5 % MnO2 glass has the most stable structure against gamma irradiation, the lowest ultrasonic velocity and wave passage, and the highest attenuation of waves, ensuring the high ability of the prepared glasses to inhibit the echoes. Experimental shielding parameters such as mass (MAC) and linear attenuation coefficients (LAC), half value layer (HVL) and tenth value layer (TVL) were measured for gamma rays and removal cross section area was measured for neutrons. Theoretical studies by WinXcom program revealed satisfactory settlement, with the experimental examinations displaying a high efficiency of the glasses to shield gamma rays especially the glass with 0.5 % MnO2, which has the highest attenuation and the lowest HVL and TVL. Therefore, the high efficiency of the glasses to be used as radiation shielding applicants in radiation institutes before 50 kGy, i.e. as storage containers for radioactive wastes in nuclear medicine.

Measurement Method of Stress in High-Voltage Cable Accessories Based on Ultrasonic Longitudinal Wave Attenuation.

High-voltage cables are the main arteries of urban power supply. Cable accessories are connecting components between different sections of cables or between cables and other electrical equipment. The stress in the cold shrink tube of cable accessories is a key parameter to ensure the stable operation of the power system. This paper attempts to explore a method for measuring the stress in the cold shrink tube of high-voltage cable accessories based on ultrasonic longitudinal wave attenuation. Firstly, a pulse ultrasonic longitudinal wave testing system based on FPGA is designed, where the ultrasonic sensor operates in a single-transmit, single-receive mode with a frequency of 3 MHz, a repetition frequency of 50 Hz, and a data acquisition and transmission frequency of 40 MHz. Then, through experiments and theoretical calculations, the transmission and attenuation characteristics of ultrasonic longitudinal waves in multi-layer elastic media are studied, revealing an exponential relationship between ultrasonic wave attenuation and the thickness of the cold shrink tube. Finally, by establishing a theoretical model of the radial stress of the cold shrink tube, using the thickness of the cold shrink tube as an intermediate variable, an effective measurement of the stress of the cold shrink tube was achieved.

Ultrasound Control of Pickering Emulsion-Based Capsule Preparation.

Capsules with microparticle shells became of great interest due to their potential in many fields. Those capsules can be fabricated at high temperatures from particle-stabilized emulsions (Pickering emulsions) by sintering together particles that cover droplets. One of the problems with such an approach is accurately controlling whether particles are already sintered and creating the rigid capsule shell of a capsule. Here, we propose using a non-destructive ultrasound method for monitoring Pickering emulsion-based capsules prepared using heating under an alternating magnetic field. The polyethylene microparticles that were responsive to temperatures higher than 112 °C were used as droplet stabilizers together with iron oxide nanoparticles. During the coalescence of the droplets, facilitated by an external electric field, the ultrasonic attenuation increased, giving evidence that the ultrasound method detects structural changes in Pickering emulsions. The main change was the difference in the droplets' size, which was also observed via optical microscopy. The attenuation of ultrasound increased even more when measured after magnetic heating for the same concentration of particle stabilizers. Simultaneously, the values of ultrasonic velocity did not exhibit similar variety. The results show that the values of the attenuation coefficient can be used for a quantitative evaluation of the capsule formation process.

Online ultrasonic monitoring of FDM nozzle temperature based on metamaterial buffer rod

Abstract Fused deposition modeling (FDM) has been widely used for fabricating parts with complex geometries. However, during the printing process the nozzle temperature fluctuates which may cause nozzle blockage, inter-filament delamination, over-melting, etc. Therefore, it is of significance to develop an online and in-situ nozzle monitoring system which could overcome such drawbacks for quality assurance. In this work, a multifunctional system is designed by incorporating a traditional ultrasonic probe and a metamaterial buffer rod to online monitor the nozzle temperature and ensure a correct extrusion force and speed. A parametric simulation model is first constructed implicitly based on thermal-acoustic metamaterial structures for the buffer rod. Secondly, since the high-fidelity calculation is computationally expensive, an efficient surrogate model with kriging approach is constructed based on the dataset drawn from limited trials for rapid prediction. Thirdly, multidisciplinary optimization is performed by the NSGA-III algorithm considering the thermal insulation performance, ultrasonic attenuation and structure integrity. The rod is fabricated according to the best parameters decided. A cross-correlation algorithm is calibrated with thermocouple measurement after waveform recording at different temperatures. The online and in-situ temperature measurement can be realized during 3D printing successfully eventually. This will help to improve the printing quality with potential feedback strategies.

Quality Evaluation of Argan Oil as a Food Product Using Ultrasonic Characterization

Abstract Start This study focuses on evaluating the quality of food-grade argan oil, an essential component of Moroccan cuisine, using experimental ultrasonic characterization. Variations in ultrasonic velocity and attenuation with temperature were exploited as significant parameters for quality control of argan oil. The results reveal an inverse correlation between ultrasonic velocity and temperature, providing a unique model for the studied samples of argan oil. The measurements also show that the acoustic attenuation of argan oil decreases with temperature, while it increases with the volumetric fractions of sunflower oil added to argan oil. The data collected during this experimental study demonstrate that the velocity of the mixture of argan oil and sunflower oil increases with rising temperature. It was observed that both ultrasonic parameters of this mixture are challenging to detect by ultrasound. Ensuring the reproducibility of measurements under the same conditions, reference graphs are established to detect adulteration, especially when considering blends of argan oil with sunflower oil.

Theoretical analysis of the dimensionality of ultrasonic attenuation in polycrystalline materials with elongated grains

Abstract In the present work, the grain scattering-induced attenuation coefficient is obtained for longitudinal bulk waves in untextured cubic polycrystalline materials with elongated grains using proposed 2D and 3D theoretical models. These models are obtained based on previously developed 2D and 3D models for equiaxed grains. Comparison of the 2D and 3D models allows an analysis of the dimensionality of grain scattering-induced attenuation, which involves more complex mechanisms with elongated grains. In the higher stochastic scattering regime, both 3D and 2D longitudinal attenuations are found to be dependent on the grain size parallel to the wave propagation. In the Rayleigh scattering regime the 3D attenuation is volume dependent and in contrast, the 2D longitudinal attenuation is found to be cross-section dependent and is therefore helpful for identifying the 3D grain shape/rotation.

Laser ultrasonic characterization of grains in titanium alloy by the inversion method

Abstract The polycrystalline materials have been usually described by the average grain size (AGS). This paper provides a nondestructive method for determination of the AGS in titanium alloy from an inversion of experimental ultrasonic attenuation spectrum (UAS). The detailed analyses of the inverse algorithm and sensitivity of UAS to the AGS are presented, and the sensitivity is identified as a criterion for selecting the experimental data of UAS used in inversion. An example of the inverse method and experimental measurement for UAS comparison was given for the titanium alloy specimen with the AGS of 26 μm. The relative error between the AGS determined by the inversion and scanning electron microscope (SEM) observation was found to be about 1.5 %. The provided method demonstrates the feasibility of laser ultrasonic technology used for the non-destructive evaluation of AGS in polycrystalline materials.

Ice matrix composites for Cryo-ultrasonic testing

Cryo-ultrasonic testing utilizes polycrystalline ice coupling to enable the inspection of metallic components with complex shape. The relatively high velocity of compressional waves in ice (approximately 4000 m s−1) and its ability to support the propagation of shear waves, significantly strengthen the ultrasonic transmission through curved interfaces over conventional water coupling. This paper explores the possibility of further enhancing the ultrasonic properties of ice by dispersing solid particles in water before it is frozen. Complex physicochemical phenomena occur when aqueous dispersions freeze which can lead to a solid material with microstructural characteristics that may be unfavorable to the propagation of ultrasonic waves. Here, these effects are controlled to produce a composite material consisting of alumina nanoparticles in an ice matrix. The composite exhibits compressional and shear wave velocities of approximately 4800 m s−1 and 2700 m s−1 , respectively. Importantly, the mass density of the material is more than twice as large as the density of water. Finally, it is shown that a phenomenon similar to a glass transition occurs during freezing which results in low ultrasonic attenuation when the temperature approaches – 100 °C.

Impact of temperature and relative humidity variations on coda waves in concrete

The microstructure of concrete can be affected by many factors, from non-destructive environmental factors through to destructive damage induced by transient stresses. Coda wave interferometry is a technique that is sensitive enough to detect weak changes within concrete by evaluating the ultrasonic signal perturbation compared to a reference state. As concrete microstructure is sensitive to many factors, it is important to separate their contributions to the observables. In this study, we characterize the relationships between the concrete elastic and inelastic properties, and temperature and relative humidity. We confirm previous theoretical studies that found a linear relationship between temperature changes and velocity variation of the ultrasonic waves for a given concrete mix, and provide scaling factors per Kelvin for multiple settings. We also confirm an anti-correlation with relative humidity using long-term conditioning. Furthermore, we explore beyond the existing studies to establish the relationship linking humidity and temperature changes to ultrasonic wave attenuation.

Sideband Peak Count – a new nonlinear ultrasonic technique for monitoring damage progression in engineering materials

Linear ultrasonic (LU) techniques used by majority of the researchers working in material damage monitoring, are reliable for detecting relatively large defects. If the defect dimensions are in the range of the ultrasonic wavelength or larger, then those defects can be detected by analyzing the scattered ultrasonic fields. Material damage affects LU parameters such as ultrasonic wave speed and attenuation and their changes are detectable for relatively large defects. However, for small defects (when defect dimensions are significantly smaller than the wavelength of the propagating signal) the changes in the LU parameters are too small to detect or measure reliably. For detecting small defects engineers often use high frequency ultrasonic signals to make the defect dimensions greater than the wavelength. However, high frequency signals attenuate quickly and therefore, only very small regions near the ultrasonic probe can be inspected in this manner. Inspecting large structures by high frequency ultrasonic signals requires moving the probe mechanically from one point to the next and therefore, can be very time consuming. Nonlinear ultrasonic (NLU) technique on the other hand does not need to satisfy this restricting condition that the wavelength of the signal must be smaller than the defect size. NLU works well when the signal wavelength is much larger than the defect size. Therefore, relatively low frequency signals that can propagate a long distance and monitor a large area of a structure can be used for NLU measurements. Different NLU techniques can be used for detection and monitoring of small damages in a specimen. A relatively new NLU technique called the Sideband Peak Count-Index or SPC-I technique has been developed by the author and his collaborators. SPC-I technique for monitoring different types of materials – composites, metals, concrete, and other cement-based materials has been found to be effective. Along with those success stories of SPC-I the effect of topography and the advantage of topological sensing is also discussed in this presentation.

High-resolution defect imaging of composites using delay-sum-and-square beamforming algorithm

Abstract High-resolution ultrasonic imaging for defects in anisotropic multilayer carbon fiber reinforced polymers (CFRPs) is challenging because of the severe ultrasonic attenuation and the low signal-to-noise ratio (SNR) of echoes. The existing delay-multiply-and-sum (DMAS) beamforming outperforms delay-and-sum (DAS) beamforming in resolution, but with high computational complexity and energy loss. This paper presents a novel delay-sum-and-square (DSAS) beamforming algorithm. It takes full advantage of spatial coherence of captured data in the receiving and transmitting apertures. The non-coherent components caused by background noise are suppressed during the imaging. The back-wall reflection method (BRM) is used to correct the direction-dependent velocity. Full-matrix data is experimentally captured and processed on three different CFRP samples. Compared with DAS and DMAS, DSAS has a significant improvement in resolution, SNR and contrast. It demonstrates excellent defect characterization and noise suppression capability with only 17.4% computation time of DMAS.

Development and study of ultrasonic pulse velocity measurement system using wave analysis and two-point detection approach

Abstract This article focuses on the development and analysis of an Ultrasonic Pulse Velocity (UPV) measurement system used for the evaluation of concrete and Reinforced Cement Concrete (RCC) in civil construction. The UPV tester is essential for on-site assessments of structures, as it is used to measure the velocity of ultrasonic waves within the material, directly correlating with its strength. UPV testing is affected by the attenuation of ultrasonic waves in concrete, particularly due to the interfacial transition zone. Excess ultrasonic attenuation results in the reduction in the received signal amplitude which may also results in the omission of the initial pulses due to threshold comparison at the receiver. The study highlights the impact of receiver gain on threshold error and discusses the limitations associated with ADC sampling rate and amplitude resolution. UPV measurement, including counter or data acquisition approach, have error contributions associated with threshold voltage comparison. The error due to threshold amplitude selection is quantified, emphasizing the importance of accurate signal analysis, particularly in highly attenuating medium. The article presents the design and development of a PC-based UPV tester with automatic threshold error compensation. The system includes a transmitter, receiver, 32-bit microcontroller, and a Graphical User Interface (GUI) for data analysis. The article introduces a two-point linear detection logic to minimize errors caused by selected signal amplitude and omission of initial pulses in transit time measurements. The proposed method provides effective resolution of 10 ns through software, even at low sampling rate of 2 MS/s. The experimental results demonstrate the effectiveness of the developed UPV tester, with comparisons to a reference calibration facility at CSIR-NPL. The standard deviation in the ultrasonic transit time measurement by the developed UPV device, with threshold error correction, was ±70 ns.

Effect of ultrasonic attenuation characteristics on forming accuracy of ribbed cylindrical parts in ultrasonic-assisted spinning process

Effect of ultrasonic attenuation characteristics on forming accuracy of ribbed cylindrical parts in ultrasonic-assisted spinning process

Ultrasonic and micrograph-based quantification of material characteristics for in-situ AFP composite structures

Achieving the maximum potential of parts manufactured with in-situ consolidation thermoplastic Automated Fiber Placement without a final bulk consolidation is a challenging task. This is due partially to the continual development of the technology itself and partially due to material defects which are not fully removed during part manufacturing. In this paper, a methodology is presented for the evaluation of prepreg tape and laminate quality relevant to the manufacturing process. A novel approach is presented to quantify tape quality and the fiber volume content distribution, porosity, all of which are identified as significant influences on laminate quality. A new approach to ultrasonic testing is applied for quantitative porosity analysis promising advantages over conventional methods. Laminate porosity was successfully measured using the proposed pulse-echo ultrasonic attenuation method. The fiber content distribution from the tape used in testing shows characteristics interpreted as unfavorable for high quality in-situ AFP.

Sideband Peak Count – a new nonlinear ultrasonic technique for monitoring damage progression in engineering materials

Linear ultrasonic (LU) techniques used by majority of the researchers working in material damage monitoring, are reliable for detecting relatively large defects. If the defect dimensions are in the range of the ultrasonic wavelength or larger, then those defects can be detected by analyzing the scattered ultrasonic fields. Material damage affects LU parameters such as ultrasonic wave speed and attenuation and their changes are detectable for relatively large defects. However, for small defects (when defect dimensions are significantly smaller than the wavelength of the propagating signal) the changes in the LU parameters are too small to detect or measure reliably. For detecting small defects engineers often use high frequency ultrasonic signals to make the defect dimensions greater than the wavelength. However, high frequency signals attenuate quickly and therefore, only very small regions near the ultrasonic probe can be inspected in this manner. Inspecting large structures by high frequency ultrasonic signals requires moving the probe mechanically from one point to the next and therefore, can be very time consuming. Nonlinear ultrasonic (NLU) technique on the other hand does not need to satisfy this restricting condition that the wavelength of the signal must be smaller than the defect size. NLU works well when the signal wavelength is much larger than the defect size. Therefore, relatively low frequency signals that can propagate a long distance and monitor a large area of a structure can be used for NLU measurements. Different NLU techniques can be used for detection and monitoring of small damages in a specimen. A relatively new NLU technique called the Sideband Peak Count-Index or SPC-I technique has been developed by the author and his collaborators. SPC-I technique for monitoring different types of materials – composites, metals, concrete, and other cement-based materials has been found to be effective. Along with those success stories of SPC-I the effect of topography and the advantage of topological sensing is also discussed in this presentation.

Improved Formulae for Low-Frequency Ultrasonic Attenuation in Metals

A range of ultrasonic techniques associated with the nondestructive evaluation of metals involves the propagation of low-frequency elastic waves. Metals that are isotropic and homogeneous in the macroscopic length scale contain elastic heterogeneities, such as grain boundaries within the microstructures. Ultrasonic waves propagating through such microstructures get scattered from the grain boundaries. As a result, the propagating ultrasound attenuates. The mass density and the elastic anisotropy in each constituent grain govern the degree of heterogeneity in the polycrystalline aggregates. Existing elastodynamic models consider first-order scattering effects from grain boundaries. This paper presents the improved attenuation formulae, for the first time, by including the next order of grain scattering effects. Results from investigating 759 polycrystals reveal a positive correlation between the effects of higher-order scattering from grain boundaries and the degree of heterogeneity. Thus, higher-order grain scattering effects are now known. These results motivate further investigation into higher frequencies and strongly scattering alloys in the future.