Ultrasonic Response Research Articles

Opportunities and Challenges for Predicting the Service Status of SLM Metal Parts Under Big Data and Artificial Intelligence.

Selective laser melting (SLM) technology is a high-end dual-use technology that is implemented in aerospace and medical equipment, as well as the automotive industry and other military and civilian industries, and is urgently needed for major equipment manufacturing and national defense industries. This paper examines the challenges of uncontrollable service states and the inability to ensure service safety of SLM metal parts under nonlinear and complex operating conditions. An overview of the prediction of the service status of SLM metal parts was introduced, and an effective approach solving the problem was provided in this paper. In this approach, the cross-scale coupling mechanism between mesoscopic damage evolution and macroscopic service state evolution is clarified by tracking the mesoscopic damage evolution process of SLM metal parts based on ultrasonic nonlinear responses. The failure mechanism is organically integrated with hidden information from monitoring big data, and a "chimeric" model to accurately evaluate the service status of SLM metal parts is constructed. Combining nonlinear ultrasound technology with big data and artificial intelligence to construct a "chimeric" model and consummate the corresponding methods and theories for evaluating the service status of SLM metal parts is an effective way to reveal the mesoscopic damage evolution and service status evolution mechanisms of SLM metal parts under complex factor coupling, and to accurately describe and characterize the service status of parts under complex operating conditions. The proposed approach will provide a theoretical basis and technical guarantee for the precise management of SLM parts' service safety in key equipment fields such as aerospace, medical equipment, and the automotive industry.

Performance optimization of AlN ultrasonic thin-film sensors deposited by RF magnetron sputtering

The AlN thin-film ultrasonic transducers were deposited by reactive RF magnetron sputtering technique. The effects of deposition parameters: target-substrate distance, argon-nitrogen flow ratio, deposition time, substrate temperature and radial distance from the deposition center on the ultrasonic performance of AlN thin films were studied. A metal electrode layer was deposited on the AlN film transducer to fabricate an ultrasonic temperature sensor, and the effects of the size and thickness of the electrode layer on the performance of the sensor were studied. Piezoelectric response measurements were performed in air over a temperature range of −60 °C–900 °C, and the dependence of ultrasonic response (time-of-flight and pulse echo amplitude) on temperature was analyzed. Long-term heat treatment in air at 750 °C for 128 h showed that the high-entropy alloy oxide protective layer could effectively delay oxidation of the AlN layer and improve the service life of the sensor.

Inverse problem-solving method applied to the acoustic characterisation of a thin film via the Debye series method (DSM)

ABSTRACT The study of the ultrasonic acoustic response of materials is of increasing interest for the characterisation of high-frequency applications. In this work, some elastic properties (acoustic velocity and acoustic attenuation) and some physical properties (thickness and density), together with the phase shift of the transducer, are estimated via one method. Scanning acoustic microscopy was performed via an innovative and different method using a high-frequency (50 MHz) planar wave transducer. In addition, the Debye series model (DSM) was used to model the acoustic response of the bilayer structure of the glass substrate and the resin‒epoxy sample. The inverse problem of estimating the acoustic parameters that results in a DSM reflected echo that matches the experimental signal is solved by proposing an innovative step-by-step curve fitting algorithm. The algorithm for solving the inverse problem is then optimised via relative mean square error (RMSE) curves, resulting in a robust method for assessing the uniqueness of the multiparameter solution.

Ratcheting damage evaluation based on critically refracted longitudinal wave combined with recurrence quantification analysis

Excessive accumulation of irreversible plastic strain in ratcheting poses a highly urgent need in early-stage damage evaluation. A strategy integrating critically refracted longitudinal (LCR) wave with recurrence quantification analysis (RQA) is proposed for iron. The signals at different damage stages are reconstructed in multidimensional phase space, and three features, recurrence rate RR, determinism DET, and entropy ENTR, are extracted. With increasing ratcheting cycle, the normalized ENTR difference, ENTRdif, exhibits an obvious increase within ∼1 % life followed by a stabilization trend, while the normalized RR difference, RRdif, fluctuates after an initial rapid rise. Both features show higher sensitivity to the amplitude-based indexes in the LCR wave and pulse-echo methods. The ultrasonic response mechanism is discussed with the rearrangement and mobility of dislocations confirmed by microstructural observation.

A study of the ultrasonic and audible frequency response of commercial loudspeakers for use as parametric acoustic arrays

Parametric acoustic loudspeakers (PAL), also known as parametric acoustic arrays (PAA), are speakers that use ultrasonic waves to generate directive audible sound. They emit an ultrasonic carrier modulated in amplitude by the desired audible signal, and due to non-linear propagation in air, this signal is reproduced in the audible range. Typical applications include audio reproduction for entertainment, but also active noise control and acoustic measurement of material properties. PAA typically consist of an array of piezoelectric transducers set on a surface. However, there are other speakers in the market that, due to their characteristics, could also achieve the PAL effect. This work examines the performance of commercial speakers when reproducing. First, the ultrasonic frequency response of each speaker is examined in free-field conditions using exponential sine sweeps (ESS). This enables searching for potential carrier frequencies to modulate the ESS in the ultrasonic range. The ESS are next modulated in the desired ultrasonic region and emitted through each speaker, obtaining their audible and ultrasonic impulse responses. The results show that some commercial speakers can also operate as PALs, which is interesting from an industrial point of view as it lowers costs and simplifies the assembly process.

Enhancing Ultrasonic Echo Response of AlN Thin Film Transducer Deposited by RF Magnetron Sputtering.

Accurate measurement of the pretightening stress for bolts has great significance for improving the assembly quality and safety, especially in severe environments. In this study, AlN thin film transducers were deposited on GH4169 nickel base alloy bolts using the RF magnetron sputtering, enabling a systematic investigation into the correlation between structures and the intensity of ultrasonic echo signals. Employing the finite element method resulted in consistency with the experimental data, enabling further exploration of the enhancement mechanism. With the increasing thickness of both the piezoelectric layer and the electrode layer, the intensity of the ultrasonic echo signals saw a great enhancement. The maximum-intensity observed increase is 14.7 times greater than that of the thinnest layers. Specifically, the thicker piezoelectric layer improves its mechanical displacement, while the increased thickness of the electrode layer contributes to better densification. An electrode diameter of nearly 4 mm is optimal for an AlN thin film transducer of M8 bolts. For pretightening the stress measurement, the sample with a strong and stable echo signal shows a low measurement error of pretightening below ±2.50%.

Dual-Wave ZnO Film Ultrasonic Transducers for Temperature and Stress Measurements.

ZnO film ultrasonic transducers for temperature and stress measurements with dual-mode wave excitation (longitudinal and shear) were deposited using the reactive RF magnetron sputtering technique on Si and stainless steel substrates and construction steel bolts. It was found that the position in the substrate plane had a significant effect on the structure and ultrasonic performance of the transducers. The transducers deposited at the center of the deposition zone demonstrated a straight columnar structure with a c-axis parallel to the substrate normal and the generation of longitudinal waves. The transducers deposited at the edge of the deposition zone demonstrated inclined columnar structures and the generation of dominant shear or longitudinal shear waves. Transducers deposited on the bolts with dual-wave excitation were used to study the effects of high temperatures in the range from 25 to 525 °C and tensile stress in the range from 0 to 268 MPa on ultrasonic response. Dependencies between changes in the relative time of flight and temperature or axial stress were obtained. The dependencies can be described by second-order functions of temperature and stress. An analysis of the contributions of thermal expansion, strain, and the speed of sound to changes in the time of flight was performed. At high temperatures, a decrease in the signal amplitude was observed due to the decreasing resistivity of the transducer. The ZnO ultrasonic transducers can be used up to temperatures of ~500 °C.

Testing of battery separators: transducers and methods for air-coupled ultrasonic sensing.

Abstract Battery separator me3mbranes are thin polymeric microporous films placed between battery electrodes. They are a key component that strongly affects both battery performance and security and controlling its main properties is critical for the industry. In particular, the manufacturing process demands tests that allow checking both the mechanical integrity (porosity, thickness, pore size, etc.) of the materials and the consistency of these properties during the construction of the batteries. The use of an air-coupled ultrasonic system is proposed in this work. It is expected that this will make possible the non-destructive and quick testing of these materials, in order to evaluate thickness, stiffness, pore distribution and pore size of the separator. By means of three pairs of transducers, the modulus and phase of the transmission coefficient was measured from 0.35 to 1.4 MHz in different materials. The measurements show a clear modification of the film response produced by the presence of porosity. This suggests that the transmission of ultrasonic waves in battery separators using air-coupled ultrasound may have two contributions: one corresponds to the propagation though the solid part, the other corresponds to propagation in the pores. The former allows to determine properties like film thickness and elastic constants, while the latter allows to determine porosity and pore size and pore tortuosity. This work set the basis for the development of a quality test for the in-line inspection of these materials during their fabrication. The observed ultrasonic response in microporous separators suggest the possibility to use low frequency air-coupled transducers with limited sensitivity, where the use of MEM transducers at industrial scale can be advantageous.

Evaluation of Material Integrity Using Higher-Order Harmonic Generation in Propagating Shear Horizontal Ultrasonic Waves.

Material nonlinearity is explored for the assessment of structural integrity. Crack-wave interactions are of particular interest. The major focus is on higher-order harmonics, generated in propagating shear horizontal (SH) waves. These harmonics are generated due to global material nonlinearity and local effects such as fatigue cracks. The theoretical background of the proposed method is explained. The method is examined using numerical simulations and experimental tests. The former involves the Local Interaction Simulation Approach (LISA), implemented for the nonlinear shear horizontal wavefield. The latter is based on a high-frequency shear excitation approach. Experimental tests are conducted using a series of beam specimens with fatigue cracks. Low-profile, surface-bonded piezoceramic shear actuators are used for excitation. The excitation frequency is selected to minimize the number of generated modes in the examined specimens. Nonlinear ultrasonic responses are collected using a non-contact laser vibrometer. The results show that higher-order harmonic generation-based on shear horizontal wave propagation-can be used for crack detection in the presence of global material nonlinearity.

Nanodelivery Optimization of IDO1 Inhibitors in Tumor Immunotherapy: Challenges and Strategies.

Tryptophan (Trp) metabolism plays a vital role in cancer immunity. Indoleamine 2.3-dioxygenase 1 (IDO1), is a crucial enzyme in the metabolic pathway by which Trp is degraded to kynurenine (Kyn). IDO1-mediated Trp metabolites can inhibit tumor immunity and facilitate immune evasion by cancer cells; thus, targeting IDO1 is a potential tumor immunotherapy strategy. Recently, numerous IDO1 inhibitors have been introduced into clinical trials as immunotherapeutic agents for cancer treatment. However, drawbacks such as low oral bioavailability, slow onset of action, and high toxicity are associated with these drugs. With the continuous development of nanotechnology, medicine is gradually entering an era of precision healthcare. Nanodrugs carried by inorganic, lipid, and polymer nanoparticles (NPs) have shown great potential for tumor therapy, providing new ways to overcome tumor diversity and improve therapeutic efficacy. Compared to traditional drugs, nanomedicines offer numerous significant advantages, including a prolonged half-life, low toxicity, targeted delivery, and responsive release. Moreover, based on the physicochemical properties of these nanomaterials (eg, photothermal, ultrasonic response, and chemocatalytic properties), various combination therapeutic strategies have been developed to synergize the effects of IDO1 inhibitors and enhance their anticancer efficacy. This review is an overview of the mechanism by which the Trp-IDO1-Kyn pathway acts in tumor immune escape. The classification of IDO1 inhibitors, their clinical applications, and barriers for translational development are discussed, the use of IDO1 inhibitor-based nanodrug delivery systems as combination therapy strategies is summarized, and the issues faced in their clinical application are elucidated. We expect that this review will provide guidance for the development of IDO1 inhibitor-based nanoparticle nanomedicines that can overcome the limitations of current treatments, improve the efficacy of cancer immunotherapy, and lead to new breakthroughs in the field of cancer immunotherapy.

Synthesis of lead-free piezoelectric potassium sodium niobates for the preparation of anti-fouling KNN porous membrane

Potassium sodium niobates (KNNs) have garnered significant attention owing to their lead-free nature and potential for use in self-cleaning membranes. This paper presents the synthesis of (K0.5Na0.5)NbO3 materials for the fabrication of porous membranes, which enable in situ ultrasonic resonance to effectively eliminate contaminants from the membrane surface. KNN powder was synthesized via solid-state reactions, and the membranes were prepared using conventional sintering techniques. The effects of ball-milling time and calcination temperature on the phase structure, pore size, permeance, flexural strength, chemical stability, and piezoelectric properties were comprehensively investigated. The optimal membranes exhibited an average pore size of approximately 300 nm, a porosity of 23 %, and permeance of 220 L m−2 h−1 bar−1 at a sintering temperature of 1050 °C. A polarized electrical field with a strength of 1 kV/mm was applied to the membranes, resulting in an ultrasonic response of 20 mV at an excitation voltage of 20 V with a frequency of 200 kHz. Furthermore, the in situ anti-fouling performance was evaluated by conducting filtration tests on a 500 ppm oil-in-water (O/W) emulsion, demonstrating that the stationary flux increased by 46.7 % when subjected to an excitation voltage of 60 V.

Ultrasparse Ultrasonic Synthetic Aperture Focus Imaging by Passive Sensing.

Ultrasonic synthetic aperture focus techniques (SAFTs) using less than the total number of available array elements to transmit ("sparse" transmissions) have been recently used in both medical imaging and industrial nondestructive testing (NDT) imaging to increase test speed and simplify multiplexer hardware. The challenge of sparse arrays is to obtain a reasonable image quality given the reduced transmitter-receiver combinations available to the beamforming process. This article proposes a "ultrasparse" SAFT method that employs a minimum number of transmitter elements (from one to four elements only) to obtain an entire full-matrix capture (FMC) set of waveforms. Specifically, a "virtual" FMC is obtained from normalized cross-power spectra between each array element pair in an implementation of "passive" ultrasonic sensing. In order to maintain high image quality without sacrificing imaging speed (e.g., applying a minimal initial time delay and keeping a short time recording window), several key steps have to be taken in this "passive" imaging mode, specifically: 1) the use of carefully designed segment-averaged normalized cross-power spectrum (NCPS) for robust passive reconstruction of the ultrasonic impulse response function (IRF) between two receivers; 2) the use of both the causal and acausal portions of the passively reconstructed IRFs; and 3) the compounding of multiple wave modes in the beamforming process. These steps also ensure the elimination of the near-field blind zone hence potentially enabling near-field imaging. The article first reviews the theory of passive IRF reconstruction between two receivers, comparing time-averaged cross correlation versus segment-averaged NCPS, and then demonstrates the application to ultrasparse SAFT FMC imaging of drilled holes in an aluminum block using a linear transducer array where only one to four elements are used in transmission.

Fabrication of elliptical-silica microfiber for ultrasound detection.

Elliptical shape microfiber enables many higher order modes compared with a circular microfiber. The small difference in the optical path length among many modes enabled multi-resonance peaks with high contrast in Mach-Zehnder (MZI) interferometers, which allows a large dynamic range and minimum detection sensitivity for broadband ultrasound sensing. In this paper, we present the design and fabrication of an ultra-compact elliptical-silica microfiber utilizing off-axis flame-drawing for ultrasound detection. The narrow transmission peak showed high contrast for ultrasensitive ultrasound wave detection. With a major-axis diameter of 6.25 µm, the elliptical-silica microfiber sensor exhibits a broadband ultrasound frequency response spanning from 20 kHz to 38.5 MHz. Furthermore, it achieves a signal-to-noise ratio (SNR) of up to 80 dB at 1 MHz, which is the resonance frequency of the microfiber and the linear response under driving voltages of 3-10 V for the PZT ultrasound generator. This low-cost microfiber sensor offers exceptional sensitivity across a broad ultrasonic bandwidth response, making it an ideal choice for nondestructive testing (NDT) and medical imaging applications. Its compact size and immunity to electric and magnetic fields further enhance its utility in various environments.

Machine learning modeling for ultrasonic quality attribute assessment of pharmaceutical tablets for continuous manufacturing and real-time release testing

In in-process quality monitoring for Continuous Manufacturing (CM) and Critical Quality Attributes (CQA) assessment for Real-time Release (RTR) testing, ultrasonic characterization is a critical technology for its direct, non-invasive, rapid, and cost-effective nature. In quality evaluation with ultrasound, relating a pharmaceutical tablet’s ultrasonic response to its defect state and quality parameters is essential. However, ultrasonic CQA characterization requires a robust mathematical model, which cannot be obtained with traditional first principles-based modeling approaches. Machine Learning (ML) using experimental data is emerging as a critical analytical tool for overcoming such modeling challenges. In this work, a novel Deep Neural Network-based ML-driven Non-Destructive Evaluation (ML-NDE) modeling framework is developed, and its effectiveness for extracting and predicting three CQAs, namely defect states, compression force levels, and amounts of disintegrant, is demonstrated. Using a robotic tablet handling experimental rig, each attribute’s distinct waveform dataset was acquired and utilized for training, validating, and testing the respective ML models. This study details an advanced algorithmic quality assessment framework for pharmaceutical CM in which automated RTR testing is expected to be critical in developing cost-effective in-process real-time monitoring systems. The presented ML-NDE approach has demonstrated its effectiveness through evaluations with separate (unused) test datasets.

Ultrasonic metrics for large-area rapid wrinkle detection and classification in composites

Due to their high strength-to-weight ratio, composite materials are now in use in many high-stress applications, particularly where light weight is also a requirement. In these situations, the detrimental knock-down in mechanical strength due to an out-of-plane wrinkle defect can have serious consequences and is the reason for a requirement to rapidly detect any such wrinkles at manufacture. Unfortunately, current ultrasonic inspection techniques used for quality control at manufacture are not sensitive enough to detect these wrinkles above coherent structural noise variations. This paper exploits the ply resonance that is a characteristic of multi-layer structures to generate two new metrics for both detection and classification of out-of-plane wrinkles, due to their perturbations of the ply spacing. These can be measured at every location on a structure using the instantaneous frequency, which is the rate of change of phase in the pulse-echo ultrasonic response. The proposed two new metrics for detection and classification of wrinkles are mean spacing and spacing difference and they can be applied to each waveform in real time, as it is acquired. Use of an analytical model to predict the ultrasonic response of the structure has allowed an understanding of how these metrics will be affected by various wrinkle types and how they can not only detect wrinkles but also classify the type of wrinkle and provide an approximate indication of severity. Three main types of wrinkle are considered: classic wrinkles near the mid-plane of a structure, back-surface wrinkles formed from a resin bulge near the back of a structure and folded wrinkles where several plies can be folded over completely in the bulk of the structure. Both simulations and experimental results demonstrate the effectiveness of these metrics on various types of structure, including carbon-fibre and hybrid carbon/glass-fibre composites with a range of ply thicknesses and wrinkle types.

Ultrasparse ultrasonic synthetic aperture beamforming via passive sensing

This presentation will describe the implementation of a passive ultrasonic sensing technique to achieve ultrasparse-transmission Synthetic Aperture Focusing (SAF) with Full Matrix Capture (FMC) capabilities. SAF ultrasonic arrays with sparse transmissions have been employed in both medical and industrial NDT imaging to increase imaging speed and simplify multiplexer hardware by reducing the number of high-voltage output channels, at the expense of a reduced beamforming matrix. A technique based on passive reconstruction of the ultrasonic Impulse Response Function (IRF) between two receivers will be demonstrated to create a “virtual” FMC capture while keeping a minimum number of physical transmitters, hence an ultrasparse-transmit array with full synthetic focusing capabilities. Several key steps of this passive beamforming approach will be discussed from both a theoretical and an experimental standpoint. The technique will be demonstrated for the imaging of drilled holes in an aluminum block using a linear, 64-element transducer array and only 1–4 physical transmitters. While the results presented have direct application to NDT imaging of solids, many of the aspects can be potentially applied to ultrafast imaging in the medical field, as well as to seismic interferometry for the health monitoring of civil structures.

Ultrasonic machining response and improvement mechanism for differentiated bio-CoCrMo alloys manufactured by directed energy deposition

The post-fabrication machining of additively manufactured biomedical parts is essential for achieving dimensional accuracy. However, conventional machining encounters issues in dealing with the growing demand for surface quality and the inherent defects of parts. To improve the machining quality, the correlation between material variations and ultrasonic machining quality is investigated in terms of material properties. This variation induced by additive strategies is experimentally revealed and the mechanism for this difference is further explained through molten pool dynamic simulation. In addition, to elucidate the unique machining advantages, a hybrid cutting simulation is implemented to analyze the improving behavior of ultrasonic vibration on the common defects of additively manufactured parts. Taken together, this study demonstrates the role that material property differences play in post-fabrication machining and validates the superiority of ultrasonic machining as a post-fabrication machining method for additively manufactured parts.

Anisotropic and heterogeneous acoustoplasticity of α-Ti during ultrasonic vibration assisted compression: Modeling and experiments

Introducing ultrasonic vibration (UV) into the plastic deformation process is a promising and efficient way to improve the formability of metallic materials. However, the acoustoplasticity of α-Ti with pronounced anisotropic behavior during UV-assisted deformation is still not well understood, and the underlying mechanisms associated with the ultrasonic effect on multiple slip/twinning systems remain ambiguous. In this research, the anisotropic and heterogeneous acoustoplasticity of α-Ti was investigated through modeling and experiments. A novel acoustic crystal plasticity model considering the anisotropic ultrasonic response of multiple slip/twinning systems was proposed, in which the ultrasonic softening is determined by the coupling effect of crystal orientation, mechanical threshold, and ultrasonic energy density. The proposed model was validated through the mechanical response of the UV-assisted compression and the twin volume fraction of α-Ti specimens along RD, TD, and ND directions. Full-field crystal plasticity simulations regarding UV-assisted compression were carried out. Then the mechanism of the acoustoplasticity of α-Ti was explored via the analysis of ultrasonic activation on multiple slip/twinning systems and the grain scale deformation behavior. A considerable anisotropic and heterogeneous ultrasonic softening effect of α-Ti was found, and the anisotropy as well as the magnitude of ultrasonic softening increase with the ultrasonic energy density. The ultrasonically activated deformation modes gradually change from prismatic slip and tensile twinning to basal slip and compressive twinning from RD, TD to ND specimens, which results in a higher average CRSS decrease and more pronounced ultrasonic softening macroscopically. The grain scale stress inhomogeneity of α-Ti is relieved under UV, and the local deformation and grain rotation are both enhanced. The dislocation motion and twinning behavior are both promoted by UV. The facilitated twinning behavior can be attributed to the enhanced dislocation assisted nucleation and propagation of deformation twins under UV. These findings provide a fundamental understanding of the anisotropic and heterogeneous acoustoplasticity of α-Ti during the UV-assisted deformation process.

Remaining capacity prediction of Li-ion batteries based on ultrasonic signals

ABSTRACT The estimation of Li-ion battery degradation performance is the key to the safe and effective operation. The current estimation methods for Li-ion battery degradation performance are mainly based on indirect electrical characteristic parameters such as voltage and current, which lack the direct characterization of internal materials, which will affect the accuracy and real-time performance of the prediction. Ultrasonic wave can directly characterize the changes in internal material properties of Li-ion battery during charging-discharging cycles. At present, the correlation between ultrasonic signal and Li-ion battery degradation process has been proven, and the relevant ultrasonic characteristics have been analyzed and established. On the above basis, this paper designs a battery degradation performance detection platform based on ultrasonic, which obtains the ultrasonic response signal and further selects four characteristics of battery aging. Aiming at the situation that the prediction starting point cannot be determined due to the possible loss of process data during the experiment, this paper uses random sampling to establish a test set to simulate the unknown prediction starting point, and establishes a battery remaining capacity prediction method based on the combination of the main model and residual correction model. Finally, the experiment proves that the proposed model has high accuracy.

Structural optimization of photoacoustic transducer with PDMS/CSNPs nanocomposite for fatigue crack detection using laser-induced nonlinear surface waves

Laser ultrasonics is a promising non-contact inspection technique but faces challenges of low signal-to-noise and low amplitude under non-destructive thermoelastic regime. In this paper, a laser ultrasonic surface acoustic wave (SAW) modulation method and photoacoustic transducer (PAT) are proposed and combined with nonlinear wave mixing technique to inspect microscale fatigue crack. PATs comprised of candle soot nanoparticles and polydimethylsiloxane are systematically optimized and combined with a line-arrayed laser source to generate desired high-amplitude and pure fundamental SAWs. Two modulated SAWs with frequencies of 2.1 and 2.9 MHz are excited on a fatigued aluminum plate to generate nonlinear mixed components, and the ultrasonic responses over the fatigue crack regions are acquired with a scanning laser Doppler vibrometer. The localization of fatigue crack with microscale is eventually achieved by mapping the nonlinear parameter of the mixed components, which proves it a reliable and non-destructive technique to inspect the fatigue crack.