Search Results (515)

In this study, laser powder bed fusion (PBF-LB) 022Cr17Ni12Mo2 steel plates with dimensions of 50 mm × 50 mm × 2 mm were fabricated using a laser power of 206 W, a scanning speed of 900 mm/s, a hatch spacing of 90 μm, a layer thickness of 30 μm, and an interlayer scanning rotation of 67°. The specimens were then subjected to solution treatment at 900–1100 °C for 30 min and at 950 °C for 30–120 min. Unlike previous ultrasonic studies on additively manufactured metals, which mainly focused on defect detection, elastic-constant characterization, or residual stress evaluation, this work investigates whether solution-treatment-induced changes in grain size and dislocation density can be quantitatively reflected by laser-ultrasonic attenuation and further correlated with yield strength. Laser ultrasonic nondestructive testing using a 1064 nm pulsed laser with a pulse width of 8 ns and a pulse energy of 500 mJ was combined with metallographic observation, EBSD characterization, XRD analysis, tensile testing, and microhardness measurement. The results show that the solution-treated samples retained a single-phase γ-austenitic structure, while microstructural recovery, weakening of PBF-LB-induced cellular substructures, and partial annihilation of cell-wall dislocations led to a reduction in KAM-derived dislocation density from 2.04 × 10¹⁴ m⁻² to 1.45 × 10¹⁴ m⁻² and a decrease in yield strength from 466.9 MPa to 407.4 MPa. Within the present dataset, the EBSD-equivalent grain size showed an apparent positive correlation with ultrasonic attenuation, while the KAM-derived dislocation density showed an empirical negative correlation with ultrasonic attenuation. However, ultrasonic attenuation should be interpreted as a combined microstructure-sensitive response rather than as a response controlled only by EBSD-equivalent grain size or dislocation density. Based on the empirical correlations among ultrasonic attenuation, EBSD-equivalent grain size, KAM-derived dislocation density, and yield strength, a preliminary attenuation-based calibration model was established for the present solution-treated samples. The model should be regarded as an in-sample empirical calibration within the present experimental range rather than a general Hall–Petch-based predictive model. The model showed good in-sample fitting performance, with (R²) values higher than 0.85 and a maximum in-sample fitting error of 3.85%. However, because the model was established and assessed using the same eight solution-treatment conditions, it should be regarded as a preliminary calibration model within the present experimental range rather than a general predictive model. This study demonstrates the potential of laser ultrasonic attenuation for non-contact evaluation of microstructural and mechanical-property variations in solution-treated PBF-LB 022Cr17Ni12Mo2 steel. Full article

Groundwater ingress threatens the serviceability and durability of underground structures, particularly when hydrogeotechnical conditions and waterproofing details are considered separately. This study presents a diagnosis-driven assessment of a reconstructed underground shooting range tunnel where leakage persisted despite reconstruction and previous repairs. The objectives were to identify the cause-and-effect mechanism of water ingress and select a targeted, low-impact remediation strategy. The investigation combined archival analysis, three site inspections, ultrasonic testing at 24 locations, eight tomographic scans, targeted destructive verification, and three geotechnical boreholes extending to 7.5 m. Ultrasonic measurements indicated good concrete homogeneity, with a mean estimated compressive strength of 36.9 MPa and a coefficient of variation of 5.86%. Tomography indicated a 25 cm bottom slab and a 20 cm lean concrete layer, compared with the designed 30 cm and 10 cm, respectively. The original geotechnical investigation was too shallow, and the ground conditions should have been classified as difficult, corresponding to geotechnical category II. Finally, leakage was linked to groundwater underestimation, water accumulation in the backfilled excavation, absence of drainage, waterproofing discontinuities, and ineffective previous injections. Targeted reinjection and joint sealing were selected, demonstrating how integrated diagnostics can support proportionate remediation while limiting excavation, demolition, material use, and operational disruption. Full article

As the primary carrier for oil and gas transportation, pipelines are critical for the entire industry. Pipelines are continuously subjected to corrosion and abrasion in the oil and gas delivery process, leading to gradual wall thickness reduction, shortened service life, and deteriorated operational safety. Ultrasonic testing has been widely adopted for monitoring pipeline wall thickness. Conventional ultrasonic transducers possess rigid configurations, which hinder large-area inspection and exhibit poor adaptability to complex curved components. In contrast, flexible ultrasonic sensors show prominent advantages, with their small size, light weight, and excellent conformal contact with curved surfaces. Flexible piezoelectric thin-film sensors have been used in a wide range of fields. As one of the most representative piezoelectric polymers, poly(vinylidene fluoride–trifluoroethylene) (P(VDF-TrFE)) combines favorable piezoelectric coefficients and intrinsic flexibility, making it popular. Some research groups have investigated the influences of modified filler particles, doping ratios, and fabrication process optimization on the performance of P(VDF-TrFE)-based piezoelectric composites, while others have concentrated on the practical applications of existing flexible piezoelectric sensors. This study emphasizes a rapid customized fabrication strategy for flexible sensors instead of single-specification standardized probes; hence, it does not share the same comparison benchmark as conventional fixed-dimension sensors. Systematic research on flexible piezoelectric thin-film sensors is presented, including piezoelectric material modification, substrate design, laminated structural design, fabrication workflows, establishment of the testing platform, and the development of matched circuit systems. The material preparation and manufacturing processes are optimized, and a scalable technical route for fabricating flexible piezoelectric sensors is proposed. Using this route, flexible piezoelectric thin-film sensors can be rapidly tailored for different application scenarios to satisfy diverse engineering demands. Multiple experiments were conducted on pipeline samples with varying wall thicknesses and curvatures. The results verify that the sensor reaches a measurement precision of 0.01 mm, meeting the demands of high-precision pipeline structural health monitoring. Full article

Ultrasonic Lamb waves are promising for the nondestructive evaluation of silicon wafers; however, their dispersive, multimode, and orientation-dependent propagation complicates multidirectional measurements in anisotropic media. This study presents a measurement system for wedge-free, multidirectional, A0-dominant Lamb-wave interrogation in a silicon wafer. The distinctive feature of the system is the integration of a fixed normal-incidence PZT source with non-contact scanning laser Doppler vibrometry, enabling wavefield acquisition along arbitrary in-plane directions without repeated wedge coupling or directional source reconfiguration. Frequency–wavenumber analysis demonstrates an A0-dominant wavefield, with the S0-associated power virtually indistinguishable from the baseline spectrum. A noise-adaptive Hilbert-envelope time-of-flight method and locally weighted scatterplot smoothing (LOWESS) reconstruct the orientation-dependent A0 group-velocity profile. The reconstruction shows a root-mean-square percentage deviation of 1.39% relative to the theoretical group velocities obtained from numerical simulations. This capability is practically important for wafer inspection as it reduces setup complexity, thereby improving measurement consistency. Full article

Severe localized corrosion in crude unit overhead systems is a critical integrity concern, particularly under transient wetting conditions. This study combines high-frequency online ultrasonic (UT) monitoring with a simplified dew-point temperature margin (ΔT) to evaluate short-term changes in corrosion severity during operation. Wall-thickness data obtained at 12 h intervals were used to derive long-term thinning trends and a short-interval corrosion rate indicator (CR_12h). CR_12h increased as ΔT decreased, indicating that reduced dew-point margin was associated with increased corrosion severity. Although ΔT is not an exact thermodynamic dew-point prediction, it served as a practical operational proxy for transient wet-corrosion propensity. The evaluation supported partial replacement of the affected column-top region with Alloy C-276 cladding. Follow-up inspection after four years showed approximately 0.1 mm of pitting, corresponding to about 0.025 mm/y, which was approximately one order of magnitude lower than the previous Type 405 stainless-steel cladding. These results demonstrate a practical approach for linking continuous corrosion-monitoring data with operational indicators and material-selection decisions in crude unit overhead systems. The study further illustrates how monitoring-derived insights can be translated into repair planning and subsequently validated through long-term field performance following material upgrade. Full article

This study proposes an approach based on an acousto-ultrasonic method and feature-based analysis to assess the condition of cables within their anchor bases. Experimental tests were performed on several model anchor configurations, including a healthy reference (REF-1) and different degraded configurations (namely DEF-1Z, DEF-2Z, DEF-W), in order to investigate the influence of the number of broken wires on the recorded signal. The acquired signals were characterised using acoustic emission features such as amplitude, energy, duration, counts, and centroid frequency. Z-score normalisation was applied according to two strategies—joint normalisation using a reference anchor base, and reference-free normalisation—in order to better reflect in situ inspection conditions. The objective is to discriminate between healthy and degraded cable states within anchor bases, first with a reference-based approach and then without any reference. The results show that several features have strong discriminative potential. In addition, the reference-free results show good agreement between sensor positions and degraded areas, confirming the localisation of the damage. Overall, this approach appears promising for future in situ applications. Full article

The delay-and-sum total focusing method (TFM) for ultrasonic full matrix capture (FMC) depends on accurate ray path and travel time computation. In L-shaped carbon fiber-reinforced polymer (CFRP) corner parts, elastic anisotropy, multilayer stacking, and curvature-induced ray path non-uniqueness generate strong stripe-like coherent clutter (deterministic structural echoes), degrading focusing and sizing. To address this, we search multiple physically plausible candidate ray paths and propose a phase-consistency-adaptive multi-path fusion TFM (PCA-MPF-TFM) that performs pixel-wise path selection and fusion. The method is validated using pulse-echo FMC data acquired with a water-immersion linear array from a 6.4 mm-thick L-shaped CFRP specimen containing three 3 mm-diameter polytetrafluoroethylene (PTFE) inserts; the two within the concave-side inspection region were quantitatively evaluated. Compared with conventional isotropic TFM, an edge-adjacent delamination previously masked by structural noise is consistently detected with a 9.2 dB signal-to-noise ratio (SNR) and a 0.2 mm length error. For the second delamination, the SNR improves by 25 dB and the length error decreases from 0.6 mm to 0.2 mm. Experimental results demonstrate improved defect detectability and noise robustness under curved, anisotropic, and multilayer propagation while maintaining sub-millimeter sizing accuracy. Full article

The goal of this work is to develop an optimized framework for ultrasonic guided wave imaging in order to increase the precision of damage localization in planar structures. This work is novel in that it refines the Reconstruction Algorithm for Probabilistic Inspection of Damage (RAPID) by assessing how the scaling factor β affects imaging resolution. To track structural integrity, the technique makes use of a surface-mounted array of twelve piezoelectric transducers (PZT). Numerical simulations were performed on an aluminum plate with through-hole defect in order to assess the performance. To replicate realistic Lamb wave interactions, a finite element model was created using CIVA SHM software (version 2023). MATLAB (version 2022) was used to process the obtained signals in order to produce probabilistic defect distribution maps. The RAPID algorithm, optimized with a scaling factor β = 1.05, achieves relative localization accuracy, according to numerical results. The study provides a solid numerical foundation for further experimental validation by confirming that the suggested configuration detects structural damage. Full article

The propagation characteristics of ultrasonic guided waves (UGWs) in rails, together with the inherently complex inspection environment for in-service rails, pose a significant challenge for the effective detection of rail fractures or damage using UGW. To address these issues, this work proposes a feature extraction method for defect-related UGW signals in the structural health monitoring of rails. The proposed approach integrates singular value decomposition (SVD), principal component analysis (PCA), and independent component analysis (ICA). First, to eliminate periodic interference, the constructed data matrix is processed using a Hankel matrix combined with SVD, and the analysis matrix is then reconstructed for subsequent ICA processing. Second, to reduce computational complexity, the dimensionality of the analysis matrix is reduced using PCA. Finally, the independent components and their corresponding weight vectors are obtained by applying ICA to the analysis matrix. By examining whether the resulting weight vectors exhibit significant step characteristics, it is possible to determine whether the rail is defective. Experimental validation demonstrates that the proposed feature extraction method is both reliable and effective. Full article

To address the need for bubble detection in industrial silicone sealing rings, this paper presents a compact non-invasive ultrasonic monitoring system based on a capacitive micromachined ultrasonic transducer (CMUT) array, aiming to overcome the limitations of conventional X-ray inspection in terms of safety, portability, and real-time in situ monitoring. The system comprises two 8.8 mm × 8.8 mm CMUT arrays with associated transmitting and receiving circuitry. The silicone thickness is determined using the time-of-flight (TOF) method, while bubble size is quantitatively estimated by combining received signal amplitude analysis, which characterizes bubble-induced attenuation, with correlation function evaluation. Experimental measurements on industrial-grade silicone samples and finite element simulations demonstrate that the system achieves a spatial resolution of 0.5 mm and effectively captures attenuation variations caused by bubbles. The integrated strategy of TOF, amplitude analysis, and correlation assessment ensures reliable non-destructive evaluation. Compared with X-ray inspection, the proposed system is safer, more portable, and suitable for real-time on-site monitoring, thereby significantly improving quality control efficiency in silicone manufacturing. This study provides a novel CMUT-array-based solution for quantitative bubble detection in silicone media, offering both high resolution and practical application potential. Full article

With increasing rail traffic intensity, reliable detection of shallow subsurface rail damage is essential for operational safety. This critical narrative review evaluates non-destructive testing technologies relevant to defects whose active crack front or principal scattering zone lies within the upper approximately 0.5–10 mm of the rail, while treating the 10–15 mm range as a transition to deeper-defect verification. Magnetic flux leakage, magnetic particle inspection, visual inspection, eddy current testing, and conventional ultrasonic testing are first examined as screening or confirmatory comparators. The review then focuses on four ultrasonic surface-wave excitation routes—contact piezoelectric, active air-coupled, electromagnetic acoustic, and laser ultrasonic—and distinguishes source-specific laboratory capability from demonstrated field evidence. Because the cited studies use different defect geometries, rail conditions, sensor configurations, speeds, and decision criteria, their numerical values are reported as source-conditioned evidence rather than as a normalized ranking. An engineering decision matrix links defect depth and size, inspection speed, surface condition, and noise environment to a recommended screening–confirmation workflow. The synthesis identifies contact piezoelectric UT/PAUT as the most mature quantitative confirmation route, while EMAT, air-coupled UT, and laser UT retain method-specific advantages but require stronger natural-defect and in-service validation. Full article

The growing demand for meat products has made quality and safety assessment a priority throughout production, processing, storage, distribution, and consumption. Meat quality encompasses sensory attributes, physicochemical properties, nutritional composition, microbial status, freshness, and safety-related characteristics. Conventional sensory, physicochemical, and microbiological methods provide reliable reference measurements, but they are generally time-consuming, labor-intensive, destructive, and unsuitable for real-time or online inspection. This review summarizes recent advances in non-destructive technologies for meat quality assessment, including spectroscopy, imaging and machine vision, odor and taste sensing, ultrasonic and electrical methods, low-field nuclear magnetic resonance, and multi-source information fusion. After outlining the fundamental principles and representative applications of each technology, this review further compares the types of sensing information they provide, the quality attributes they are suitable for assessing, their application scenarios, practical limitations, and model validation requirements. Current evidence indicates that these technologies have considerable potential for rapid screening, process monitoring, quality visualization, and intelligent evaluation. However, practical deployment still requires reliable reference measurements, representative calibration datasets, robust models, external validation, and standardization across instruments and production conditions. Future research should prioritize sensor miniaturization, calibration transfer, standardized datasets, explainable intelligent evaluation, and practically deployable multi-source fusion. Full article

Pipeline corrosion critically threatens the safe operation of chemical industrial park pipeline networks, making accurate corrosion growth prediction essential for preventing catastrophic failures. Mechanistic models assume steady states, which conflict with in-service corrosion dynamics; data-driven approaches, however, presume complete datasets but frequently face missing parameters due to sensor failures and limited samples from costly inspections, increasing the risk of noise and overfitting. In this paper, the TinyTransCorrosion model was proposed, which is a lightweight Transformer-based corrosion growth prediction model specifically designed for small-sample scenarios. A cross-validation residual analysis is employed for data cleaning, while five physical embedding features are constructed to encode domain knowledge and compensate for missing parameters. A compact Transformer encoder containing only 6433 parameters was adopted, and a corrosion gating mechanism along with a classification (CLS) token was introduced to achieve efficient feature interaction. Evaluated on a real-world pipeline inspection dataset with 215 records, TinyTransCorrosion attains an R² of 0.6411 and an MAE of 0.1608 mm, outperforming nine conventional baseline models, including Mean predictor, Linear Regression, Ridge, SVR-RBF, Random Forest, XGBoost, LSTM, MLP, and CNN. While these results are limited to a single-site dataset and require external validation on independent multi-source data, the proposed lightweight physics-guided architecture demonstrates promising predictive capability for small-sample pipeline corrosion assessment, with model error approaching the metrological limit imposed by field ultrasonic gauge accuracy. It provides an acceptable pathway for prioritizing inspection intervals and optimizing maintenance scheduling in resource-constrained industrial settings. Full article

The current trend in both academic research and industrial applications is to expand the use of additive manufacturing processes across an increasing number of functional domains. This has led to substantial efforts aimed at improving the overall performance of additively manufactured components, particularly those produced by Material Extrusion (MEX). One of the main limitations of MEX-fabricated parts is the presence of air voids formed between deposited lines and layers, which reduce mechanical strength and structural uniformity. In this context, the present study investigates the influence of inter-layer ironing process parameters, an approach intended to modify near-surface morphology and improve the surface quality and dimensional accuracy of two commonly used materials, namely lightweight polylactic acid (PLA-LW) and standard. The experimental setup involved varying the ironing direction, nozzle diameter, and ironing spacing, while keeping all other manufacturing parameters constant. A complete 4 × 3 × 3 factorial experimental design was employed, considering three process parameters: ironing direction at four levels, nozzle diameter at three levels, and ironing spacing at three levels, resulting in 36 parameter combinations applied to each material separately. Performance evaluation included surface roughness (S_a), Shore D hardness, waviness (W_a), microscopic morphology analysis, and qualitative ultrasonic inspection used to observe internal void-related features, whereas the quantitative analysis focused on Sa, Wa, and hardness variations. The results were compared with those obtained for specimens produced using final-layer-only ironing and no ironing. Inter-layer ironing generally improved surface quality compared with non-ironed specimens, reducing Sa by up to 85.22% and increasing Shore D hardness by up to 10.40% for individual PLA-LW specimens manufactured using the 0.4 mm nozzle. The waviness response was strongly material-dependent; increasing the ironing spacing from 0.1 to 0.3 mm reduced Wa by 47.71% for PLA-LW and 13.39% for standard PLA, while the same spacing increase reduced Sa by 25.61% for PLA-LW but increased Sa by 10.87% for standard PLA. While PLA-LW specimens exhibited localized surface defects possibly associated with the compaction or collapse of near-surface voids, standard PLA specimens showed more pronounced waviness and material accumulation, highlighting the different responses of compact and foamed polymer structures to repeated thermo-mechanical ironing actions. Full article

Magnetostrictive patch transducers (MPTs) are highly efficient for generating and detecting ultrasonic waves for non-destructive evaluation (NDE), though their use on cementitious media and fibre-reinforced concrete has not yet been investigated. In this study, a COMSOL simulation, validated with laser-Doppler vibrometry, was first used to quantify patch deformation for use in subsequent simulation of wave propagation in samples. The MPT system was then validated on thin glass plates, producing tunable A₀, S₀, and SH₀ modes through frequency-wavelength matching. In cementitious mortar plates, SH₀ and SH₁ modes were demonstrated experimentally for the first time using MPTs. The validated COMSOL model was then used to interpret complex signals in quasi-plate and half-space cementitious mortar prisms, showing that MPTs generate Rayleigh, bulk SH, and surface-skimming SH modes. In steel fibre-reinforced concrete, surface-skimming SH wave speed correlated with increases in breaking strength even in the presence of surface features such as notches. Notably, Rayleigh wave speeds could not be measured in the presence of surface features, and the Rayleigh velocities measured in the same sample, but not in the local tested area did not correlate with SH speed. This behaviour is likely due to the non-uniform distribution of material constituents, including fibre-reinforcement and coarse aggregate, combined with the different propagation paths and depth sensitivities of the reported wave modes. Overall, racetrack-coil MPTs enable multimodal inspection of cementitious media, providing information on the presence of geometric features and material properties. Full article