Propagation Characteristics Of Ultrasonic Waves Research Articles

A tunable spatial coherence imaging with ultrasonic array for defects in composites

ABSTRACT Ultrasonic phased array detection technology is a promising non-destructive testing (NDT) method that has been widely used for defect detection. Due to the high attenuation characteristics of ultrasonic wave propagation in carbon fibre reinforced polymer (CFRP) and the directivity of the array elements, the possibility of false or missed detection for defects that are far from the array elements or located very close together will increase. In addition, the total focusing method (TFM) employs only the defect information contained in the full matrix capture (FMC) dataset while ignoring the spatial information of the array signals, leading to image mixed with artefact and noise. An improved method called p-weighted-TFM (p-WTFM) is proposed. First, this method scales the magnitude of time-delayed channel signal by p-th root while maintaining the phase unchanged. Second, channel summation with energy compensation and directional correction will be realised. Finally, the signal dimensionality is restored by p-th power. Experimental results show that the p-WTFM can use any rational p-value to flexibly adjust image quality. Specially, this method can accurately distinguish adjacent defects spaced 1 mm apart with p value of 2.5, and it can also detect two defects located 10 mm deep with p value of 3.0.

Ultrasonic wave characteristics in multiscale cementitious materials at different stages of hydration

Monitoring the microstructural change in cementitious materials during hydration is an essential but challenging task. Therefore, a non-invasive and sophisticated technique is warranted to understand the microscopic behaviour of the multiphase cementitious materials (where the length scale of the constituents varies from centimeters to micrometers) in different stages of hydration. Due to exothermic hydration reactions, different hydration products start to evolve with individual mechanical properties. In concrete, an interface transition zone (ITZ) appears between the aggregate surface and paste matrix, which influences the overall properties of concrete material. In the present research, 1) several wave characteristics, such as wave velocity, energy distribution, and signal phase are found out using Ultrasonic Pulse Velocity (UPV), Wavelet Packet Energy (WPE) and Hilbert Transform (HT) methods, to monitor the hydration mechanism (1d-28d) in cement-based materials with two levels of heterogeneities (cement paste and concrete, representing microscale and mesoscale, respectively). Also, the unique nonlinear behaviour is studied in the frequency domain using the promising Sideband Energy Ratio (SER) and Sideband Peak Count Index (SPC-I) methods. 2) Numerical simulations are carried out to understand the wave interaction in the developing microstructure. A discretized microstructure of cement shows microscopic details of each phase at any instant of hydration (e.g., formation stage and after complete maturity level). The experimental and numerical investigations on the characteristics of the nonlinear ultrasonic wave propagation show the impact of microstructural development of multi-scale cementitious materials during hydration.

Modelling and simulation for the investigation on the ultrasonic propagation mechanism in advanced microelectronic packages

The miniaturisation, ultra-thinness and high-density multi-layer structure of advanced microelectronic packages complicate the propagation mechanism of ultrasonic waves. In this paper, a finite element model is used to simulate ultrasonic wave propagation in flip chip packages, investigating the laws of transmission and reflection at the lamination boundaries. The acoustic field of ultrasonic transducers is simulated using MATLAB and Abaqus software. The angular spectrum method (ASM) based on the Fourier transform is adopted to more precisely reveal the distribution characteristics and attenuation relationship of near‐field ultrasonic waves. The influence of the frequency and size of the ultrasonic transducer on the propagation characteristics of ultrasonic waves is analysed. Based on an acoustic field map generated by the detection model, the waveform conversions of acoustic waves in a multi-layer structure are analysed. The results show that ultrasonic waves are mainly presented in the form of reflected and transmitted waves at the layered interface and the model with a perfectly matched layer (PML) has higher accuracy. Therefore, this method is applied to ultrasonic testing in a flip chip package, which cannot only effectively exclude interference from boundary reflection but also greatly improve the reliability of waveform conversions analysis.

Ultrasonic monitoring of plastic deformation

Accident impact assessment, safety analysis, and risk reduction are among the core research topics in the field of shipping. Analysis of emergency situations shows that all of them in most cases are characterized by a combination of some causes, one of which is the occurrence of inadmissible stress-strain state in ship elements. Determining the nature of fracture is one of the ship’s reliability improving measures. The presence of plastic deformation is a sign of the limiting condition when monitoring the structure. This leads to a visible change in the geometry of the structural components, but not to a violation of continuity, which, according to the rules of the Register, is controlled during the technical inspection of the ship. Having only regulated standard controls at its disposal, it is not possible to identify plastic deformation. The article discusses the issues of plastic deformations’ control in 10ХСНД shipbuilding steel by a method that is based on the analysis of the ultrasonic wave propagation characteristics in a controlled product. The complex of mechanical tensile tests and metallographic studies is described. The uniaxial stress-strain state of the material was created by tensile testing of a flat proportional sample. Changes in the metal structure were investigated when the required level of deformation was reached. The analysis of ultrasonic data with pulsed ultrasonic sensing and the level of second harmonic generation with continuous monochromatic ultrasonic emission is presented. Experimental data demonstrate the ability of the ultrasonic method to detect the pre-existing defects in metal under static loading, and allow for a more accurate assessment of the stress and strain state of ship's components, which can fundamentally change the picture of destruction. The use of ultrasonic plastic deformation monitoring in the framework of ship maintenance will help reduce accidents in the fleet.

Low-frequency ultrasonic array imaging for detecting concrete structural defects in blind zones

Ultrasonic array (UA) imaging is a promising non-destructive testing (NDT) method that is extensively used for defect detection. Due to the high attenuation characteristics of ultrasonic wave propagation in concrete structures and the directivity of sensors, the total focus method (TFM) easily misses specific defects in blind zones that are far from the sensors or located at a large deflection angle. To overcome this limitation, the diffusion attenuation compensation factor and solid directivity correction factor are adopted to improve the scattered signal energy of defects that are in blind zones. On this basis, the diffusion attenuation compensation method (DACM), the solid directivity correction method (SDCM), and the diffusion attenuation compensation-based solid directivity correction method (DAC-SDCM) are proposed. These methods are applied to characterize multiple circular holes in concrete structures using the dry point contact (DPC) low-frequency UA, and the detection results are evaluated from the intensity curve and detection area of ultrasonic images. The numerical and experimental results indicate that DACM is suitable for detecting defects located at longer distances, SDCM is capable of detecting defects located at larger deflection angles, and DAC-SDCM can significantly improve the detection performance of defects that are distant and have large deflection angles. The findings demonstrate that the proposed methods can significantly improve the detection ability of defects in blind zones and broaden the application of DPC low-frequency UA in the health monitoring of concrete structures.

Influence of surface roughness on laser ultrasonic detection for laser powder bed fusion manufactured 316L stainless steel

In view of the non-destructive and non-contact features, laser ultrasonic (LU) technology has long been the effective method to detect tiny defects for laser powder bed fusion (LPBF) additive manufactured specimens. Of larger concern is the variation and the corresponding mechanism on tested results of LU detection as the property of LPBF additive manufactured specimen is changed. Aiming at the property of surface roughness, this work investigated the propagation characteristics of excited ultrasonic waves in LPBF additive manufactured 316L stainless steel with different surface roughness, as well as the interaction between ultrasonic waves and artificial submillimeter holes. Both numerical simulated and experimental study were conducted. Simulated results revealed that the amplitudes of longitudinal wave (L wave) and its echo wave L1 at the holes exhibited a discernible increase as the surface was coarser. The increase in surface roughness was detrimental to the resolution of defect detection as was expected from the increased amount of noise. LPBF fabrication and the subsequent LU pulse-echo detection were conducted for 316L stainless steel. Both B-scan and C-scan were able to detect the holes with the diameter of 0.6 mm. The speckle phenomenon deriving from the increase in surface roughness emerged, corresponding to the increased ultrasonic signal energy but deteriorated resolution of detected images. It is feasible to optimize LU detected effect by minimize the surface roughness of tested specimens.

Experimental study on ultrasonic wave propagation characteristics of gas-liquid two-phase flow in riser annulus

Deepwater drilling projects face challenges such as delays in gas kick monitoring and a high risk of well control failure. How to monitor gas kicks as early and accurately as possible is one of the keys to preventing significant accidents such as well blowouts. Monitoring gas kicks at risers is a promising method for early monitoring of gas kicks in deepwater drilling. In this paper, by constructing an experimental device for ultrasonic gas kicks monitoring of the riser, the response law of the ultrasonic signal to the gas-liquid two-phase flow was tested under different air intake, drill pipe rotation speeds, and liquid flow rates. This was done by constructing an experimental riser ultrasonic gas kick monitoring device. The signal-to-noise ratio and the root-mean-square error are used as measurement standards, and the wavelet threshold noise reduction method is used to reduce noise-containing signals. The ultrasonic sensitivity characteristics of the gas-liquid two-phase flow are demonstrated by analyzing the signal in the time domain and frequency domain: peak amplitude, attenuation coefficient, wave velocity, and fundamental frequency. A non-linear relationship exists between peak amplitude, fundamental frequency, and air intake, whereas an approximately linear relationship is evident between the attenuation coefficient and wave velocity with air intake. A quantitative characterization relationship between ultrasonic characteristic parameters and air intake was obtained by conducting a multiple regression analysis using the least-squares method on the attenuation coefficient, wave velocity, fundamental frequency, and air intake. Experiments demonstrate that the relative error between the actual air intake of 86.4 % of the test data group and the theoretical air intake determined based on the quantitative characterization relationship is less than 10 %.

Laser ultrasonic detection of submillimeter artificial holes in laser powder bed fusion manufactured alloys

In the development of additive manufacturing (AM) technology, laser powder bed fusion (LPBF) is one of the important processing methods. However, the hole defects in the fabricated samples limit the development. Laser ultrasonic (LU) technology plays a major role in the detection of LPBF parts with tiny defects, which has the advantages of non-contact and non-destructive. In this work, the detection of submillimeter internal defects in four typical LPBF alloys by LU technology is studied numerically and experimentally. A multiphysics simulation model of LU detection is established to investigate the propagation characteristics of excited ultrasonic waves in different LPBF alloys and their interaction with submillimeter artificial defects. Simulation results show that the amplitude of longitudinal (L) wave at the defect is the largest in AlSi10Mg alloy, and the amplitude of L wave in the 316L alloy, Ti6Al4V alloy and In718 alloy are very close, but their phases are slightly different. The amplitude of L wave tends to decrease nearly linearly with the increase in defect diameter. Then, four typical LPBF alloys are fabricated and measured by the LU through-transmission detection. The geometric information of artificial holes with a diameter larger than 0.2 mm are clearly characterized by the LU C-scan results, indicating the prominent applicability and feasibility of LU detection on different materials fabricated by LPBF.

Physical and dynamic characteristics of high-amplitude ultrasonic wave propagation in nonlinear and dissipative media

This study presents a comprehensive investigation into the soliton solutions for the Khokhlov–Zabolotskaya–Kuznetsov ([Formula: see text]) problem using the Bernoulli sub-equation function approach, generalized Kudryashov method, and Homotopy perturbation method. The [Formula: see text] equation, a nonlinear wave equation that governs the propagation of high-amplitude ultrasonic waves through nonlinear media, is studied in detail. Perturbation theory and asymptotic expansions are employed to derive approximate solutions for the [Formula: see text] problem. These methodologies offer valuable insights into the behavior of ultrasonic waves in different media, thereby facilitating the optimization of ultrasonic transducer design and enhancing the precision of ultrasonic imaging systems. The analytical and semi-analytical methods utilized for solving the [Formula: see text] equation are computationally efficient and serve as valuable resources for researchers and engineers working in the field of ultrasonics. The outcomes of this study carry significant implications for the understanding of ultrasonic wave behavior in nonlinear and dissipative media, ultimately contributing to the development of more accurate and efficient ultrasonic imaging techniques.

Propagation characteristics of ultrasonic in SLM manufactured AlSi10Mg

Porosity is a crucial quality evaluation criterion in metal additive manufacturing. To investigate the propagation characteristics of ultrasonic longitudinal waves with different incident frequencies in AlSi10Mg prepared by selective laser melting, specimens with varying porosity were created using printing process adjustments. Ultrasonic longitudinal wave tests and COMSOL simulations based on 2.5 MHz, 3.5 MHz, 5 MHz, and 7.5 MHz incident frequencies were carried out to establish a linear relationship between average wave velocity, average attenuation coefficient, and porosity at different frequencies. Results indicate that sound velocity and porosity are inversely proportional for each frequency longitudinal wave, while the attenuation coefficient is proportional to the porosity. Linear fitting expressions suggest that the best fit for both sound velocity and attenuation coefficient occurs at 5 MHz. Simulation results demonstrate that using 5 MHz as the incident frequency can better balance detection sensitivity and linearity. These findings provide more data support for establishing the intrinsic connection between acoustic parameters and porosity of AlSi10Mg prepared by selective laser melting in the selected area and serve as a reference for selecting ultrasonic incident frequencies in practical inspection.

Quantitative analysis and evaluation of the optimization method of transformer partial discharge ultrasonic sensor monitoring

Abstract Accurate partial discharge (PD) measurement is critical to ensure the stable operation of transformers. The ultrasonic method is a low-cost, safe, and reliable technology that is widely available and provides real-time monitoring capability. The PD ultrasonic signals propagation is complex and severely attenuated in the transformer, which greatly affects the measurement accuracy of the sensor. In order to improve the accurate monitoring of PD in complicated transformer environments, an optimization monitoring method based on sub-scene detection and quantitative analysis and evaluation is proposed in this paper. Firstly, to address this concern, a sub-scene monitoring method is designed and explores the optimal monitoring points separately. In addition, establish the partition model of an oil-immersed power transformer, and compare the ultrasonic wave propagation characteristics and sound pressure attenuation characteristics of different monitoring points. Then, analyzed by wavelet transform algorithm and Pearson correlation coefficient to determine the best monitoring point location for each scene. Finally, we further tested the proposed method through extensive experiments based on simulations, testbed, and trial deployment. The experimental results have demonstrated the feasibility and accuracy of the proposed method in transformer PD monitoring under complicated environments.

Propagation Characteristics of Ultrasonic Waves Generated by Phased Array Laser in Coating/Substrate Structure

Propagation Characteristics of Ultrasonic Waves Generated by Phased Array Laser in Coating/Substrate Structure

Electromagnetic Ultrasonic Shear-Horizontal Wave to Detect Corrosion Defect of Flat Steel for Grounding Device of Transmission Pole Tower

Detecting defects in grounded flat steel is essential for ensuring the safety and reliability of transmission tower grounding devices. However, traditional inspection methods, such as physical excavation and verification, are costly and time-consuming. This paper proposes a corrosion defect detection method for flat steel transmission tower grounding devices based on electromagnetic ultrasonic SH waves. In addition, using commercial software, a three-dimensional finite element simulation model of grounded flat steel with simulated pitting corrosion defects is constructed. The specified displacements applied to multiple surface sources mimic the horizontal shear vibrations generated by the electromagnetic ultrasonic transducer on the surface of the grounded flat steel during actual inspection. A simulation was used to investigate the propagation and attenuation characteristics of shear-horizontal ultrasonic SH0guided waves for simulated corrosion defects with various geometric configurations in grounded flat steel. The simulation investigated the propagation and attenuation characteristics of the SH0 wave in grounded flat steel and the detection of various defects for linear analysis of the results. The simulation results show that the attenuation of the electromagnetic ultrasonic guided wave is small, at only 0.0016 dB/mm, and the displacement amplitude of the echo signal decreases with the increase of the SH0 wave propagation distance. Increasing the depth and length of corrosion defects increases the echo signal amplitude. At the same time, the width of corrosion defects has little effect on the echo amplitude. Finally, a flat steel defect detection experiment was conducted, and the experimental results fit with the simulation to verify the accuracy of the simulation model. This detection method introduces a new idea for the on-site detection and quantitative identification of corrosion defects in grounded flat steel, which has significant reference value and can provide a more effective and economical method for ensuring the safety and dependability of transmission tower grounding devices.

An Interface Pressure Detection Method of Cable Silicone Rubber-XLPE Based on Nonlinear Ultrasound

The interface pressure between the cable attachment and the body is crucial for the stable long-term operation of the cable. To solve the issue of interface insulation characteristics’ damage caused by the pressure transducer measurement method, a non-destructive testing method of silicone rubber interface pressure using nonlinear ultrasound is presented. Initially, the study analyzes the propagation characteristics of ultrasonic waves at the interface of cross-linked polyethylene and silicone rubber. The study also establishes the relationship between the nonlinear coefficient and the interface pressure. Subsequently, a nonlinear ultrasonic test platform is constructed using the pulse reflection method to measure the interface pressure of flat silicone rubber and cross-linked polyethylene through nonlinear ultrasonic testing. Theoretical and experimental results indicate that the fundamental amplitude of the frequency domain of the interface reflection wave decreases, and the second harmonic amplitude and nonlinear coefficient both increase as pressure increases. These results demonstrate that the nonlinear ultrasound, non-destructive testing method can accurately evaluate the interfacial pressure state of the cable accessories.

Method for Recognizing Pressing Position and Shear Force Using Active Acoustic Sensing on Gel Plates

A touch interface is an important technology used in many devices, including touch panels in smartphones. Many touch panels only detect the contact position. If devices can detect shear force in addition to the contact position, various touch interactions are possible. We propose a two-step recognition method for recognizing the pressing position and shear force using active acoustic sensing, which transmits acoustic signals to an object and recognizes the state of the object by analyzing its response. Specifically, we attach a contact speaker transmitting an ultrasonic sweep signal and a contact microphone receiving ultrasonic waves to a plate of gel. The propagation characteristics of ultrasonic waves differ due to changes in the shape of the gel caused by the user's actions on the gel. This system recognizes the pressing position and shear force on the basis of the difference in acoustic characteristics. An evaluation of our method involving a user-independent model confirmed that four pressing positions were recognized with an F1 score of 85.4%, and four shear-force directions were recognized with an F1 score of 69.4%.

Neutral Temperature Estimation of Continuous Welded Rails using Group Velocity of Ultrasonic Waves

This study proposes a neutral temperature estimation technique of continuous welded rails using group velocity of ultrasonic waves. In case of boundary-confined metallic structures, especially civil infrastructures exposed to harsh environmental conditions such as continuous welded rail, thermal stress is one of the critical control factors to avoid structural breakage and buckling. It has been known that the ultrasonic wave propagation is sensitive to target structure’s stress variation, so that the neutral temperature can be determined based on the propagation characteristics of stress-dependent ultrasonic wave. To numerically investigate the stress-dependent ultrasonic wave behavior, a 3D rail model with 1 mm mesh size was constructed using actual material property and dimensions of KR60 rail. Here, the two boundary conditions, i.e., Fix-Free and Fix-Fix boundary conditions, applied to the 3D model so that neutral temperature is extracted. The simulation results showed that the group velocity of ultrasonic waves was consistently decreased on the Fix-Free boundary condition according to temperature increase. Similarly, the group velocity on the Fix-Fix boundary condition was also decreased, but the decrement of group velocity was less than the Fix-Free boundary one due to thermal stress. Based on the observation, the stress-dependent group velocity trends can be estimated using the difference between the Fix-Free and Fix-Fix boundary resultants. Finally, the neutral temperature can be estimated by picking up the cross point of two group velocity trend graphs.

Research on the defect detection of carbon fiber reinforced polymer based on pulse laser ultrasound

The accumulation of micro damage such as matrix crack and fiber fracture in carbon fiber reinforced polymer (CFRP) under cyclic loading will seriously affect the mechanical properties of CFRP. The size of micro damage is small and the location is scattered, so it is difficult to identify accurately by traditional nondestructive testing methods. Laser ultrasonic testing technology has the advantages of non-contact, fast detection speed and wide measurement range, especially combining the advantages of long-distance excitation and large angle incidence of laser, it has great potential in the damage detection of large-scale and curved structure materials. In this paper, based on the laser thermos-elastic effect, the generation process and propagation characteristics of ultrasonic wave in CFRP are systematically studied on the basis of analyzing the distribution of temperature, stress and displacement fields after laser acting on CFRP. By analyzing and comparing the ultrasonic echo signals of different defects characteristics in CFRP, the defect depth and length are calculated based on the time when the longitudinal wave scattering wave (Lr) reaches the detector. The calculation results show that the errors of this method are about 7 % and 5 % for the detection of the depth and length of the CFRP.

Propagation characteristics of Doppler ultrasonic wave in gas–liquid two-phase flow in an offshore deepwater riser

During offshore deepwater drilling, the strata with abnormal pressure are often encountered and gas invasion and overflow occur easily. If they cannot be detected and controlled in time, blowout may happen and even get out of control, which will cause considerable economic loss and irreparable casualties and may even damage the marine ecologic environment seriously. How to monitor overflow early during deepwater drilling is a global research hot, focus and difficulty at present. In order to provide theoretical guidance for the early monitoring of overflow in the riser during offshore deepwater drilling, this paper designed an experimental device for the early monitoring of gas invasion based on the propagation principle of Doppler ultrasonic wave. Then, the installation mode and angle of Doppler probe were optimized. Finally, the propagation of Doppler ultrasonic wave in the gas–liquid two-phase flow with a void fraction of 0–46% and a liquid flow velocity of 0–0.7 m/s was experimentally studied, and the change laws of Doppler ultrasonic wave with void fraction were revealed. And the following research results are obtained. First, when the void fraction changes, the signal voltage will jump up and down at different amplitudes and frequencies on the basis of initial curve. The signal voltage amplitude increases firstly and then decreases with the increase of void fraction. Second, when the increase amplitude of mean signal voltage caused by multiple reflection is greater than the attenuation degree of ultrasonic wave, the mean signal voltage increases. Otherwise, the signal voltage decreases. Third, the fitting curve of mean signal voltage scatters and void fraction under different flow velocities and void fractions during pump stopping and starting present a change law of quadratic function. In conclusion, void fraction can be quantitatively predicted based on the measured signal voltage, so as to provide guidance for the early monitoring of riser overflow and well kill operation during offshore deepwater drilling.

Characteristics of Ultrasonic Velocity in Eggs Using HC-SR04 Module

This article discusses the characteristics of ultrasonic wave propagation in eggs. The objects used are three types of eggs: Broiler chicken eggs, and domestic duck eggs. The method of determining egg characteristics uses ultrasonic waves. Ultrasonic waves can propagate on objects, materials and components. HC-SR04 is used as a transmitter and receiver of ultrasonic waves. The ultrasonic waves transmitted to the surface of the egg. The egg spacing from the HC-SR04 module is 5 cm and 10 cm. The testing process carried out on 10 eggs of each type. The distance and propagation time parameters used as information to produce the ultrasonic velocity of the eggs. The testing and calculation process shows that duck eggs have the highest velocity value.

Non-Destructive Testing Mechanism for Pre-Stressed Steel Wire Using Acoustic Emission Monitoring.

In this paper, the guided ultrasonic wave propagation characteristics in the axisymmetric pre-stressed viscoelastic waveguide for acoustic emission (AE) monitoring, using the semi-analytical finite element (SAFE) method, is studied broadly. For the numerical investigation, a single high-strength steel wire is considered. A comprehensive and in-depth study on the AE signal’s propagation characteristics is carried out based on the SAFE method. Both undamped and damped waveguides are considered for attaining SAFE solutions and presented in a detailed manner. The SAFE method for an axisymmetric cross-section in cylindrical coordinates analyzes the two main influencing factors of steel wire in a practical scenario: Material damping and initial tension. For the effect of initial stress, the calculation shows that the initial tensile stress can increase and decrease the energy velocity and attenuation factor of most modal waves above the cut-off frequency, and the effect is linear. Some longitudinal wave modes in the high-frequency region show their potential for AE monitoring as these modes have a low attenuation factor and small external surface vibration. By considering various states of initial stress in a damped waveguide, the effect of pre-stress on the dispersion characteristics is understood in a better manner. A non-destructive testing (NDT) mechanism for pre-stressed steel wire using AE monitoring is proposed for the health monitoring of structures.