Search Results (791)

This study investigates hot-pressed composite plates manufactured from pellets obtained by mechanical recycling of post-consumer textile waste and reinforced with ground glass-fiber-reinforced polymer (GFRP) originating from wind turbine blades. Composite plates with dimensions of 200 × 330 × 8 mm were produced by hot pressing at 240 °C under 2 MPa with a heating and pressing time of 40 min. The recycled textile-derived polymer blend served as the matrix, while ground GFRP was introduced at 0, 10, 20, and 30 wt.%. Mechanical performance was evaluated using flexural and Charpy impact tests. The composites exhibited flexural strengths in the range of 9–13 MPa and impact strengths of 7.3–8.9 kJ m⁻². The results did not reveal a monotonic increase in flexural strength with increasing reinforcement content. The highest average flexural strength was observed for the unreinforced matrix, while the addition of ground GFRP resulted in comparable or slightly lower strength values accompanied by increased scatter at higher reinforcement levels. The observed behaviour may be associated with heterogeneous dispersion of ground GFRP fragments, reduced effective reinforcement length due to mechanical grinding, interfacial constraints, and defect formation within the press-consolidated structure. The findings provide insight into the structure–property relationships of recycled composite systems based on heterogeneous textile-derived polymer blends. Full article

Macrosegregation in continuous casting slabs remains a critical defect that adversely affects the homogeneity and mechanical properties of the final rolled products. Industrial experiments were conducted on E355 steel continuous casting slabs to investigate the effects of electromagnetic stirring (EMS) and soft reduction (SR) on the evolution of slab macrosegregation. Furthermore, the inheritance of segregation from the slab to the rolled plate was analyzed. The results indicate that the equiaxed crystal ratio increases and the centerline segregation decreases with increasing stirring intensity. The application of both secondary EMS and SR minimized the centerline segregation in the slab. When the current intensity was increased from 0 A to 320 A in continuous stirring mode, the equiaxed crystal fraction increased from 22.52% to 32.52%, and the centerline segregation index decreased from 1.23 to 1.17. Compared with the continuous stirring mode, the alternating stirring mode promoted a more pronounced increase in the equiaxed crystal ratio and a further reduction in the centerline segregation. The centerline segregation in the slab correlates with the banded structure observed in the rolled plate. A higher degree of slab centerline segregation corresponds to a more severe banded structure and greater fluctuations in the mechanical properties of the plate. Through parameter optimization, the recommended settings are an alternating stirring mode with a current of 320 A at 5 Hz and an SR amount of 3 mm. Under these optimized conditions, the equiaxed crystal ratio of the slab increased to 35.22%, the centerline segregation index dropped to 1.15, and the banded structure in the rolled plate was reduced to grade 2.0. Consequently, the standard deviations of the tensile strength and elongation were 8.03 MPa and 1.1%, respectively. Full article

MoS₂ acts as a high-performance lubricant, enhancing friction material stability, reducing wear and noise under extreme conditions, and preserving friction pair performance. However, its tendency to decompose and poor matrix wettability make surface modification essential for effective use in Cu-based composites. In this study, comprehensive investigations combining macro-scale and micro-scale friction experiments were conducted to examine the interfacial friction behavior of MoS₂ with different coatings and its tribological effects on copper-based composites under varying braking energy densities. The results indicate that the nickel coating suppressed MoS₂ decomposition, forming a high-strength diffusion interface with the matrix. This enhances the frictional stability and suppresses interfacial defect formation during micro-friction tests. However, the copper coating formed a poor-strength diffusion-reacting interface with matrix, leading to unstable friction at the interface and interface failure. Coating-dependent interfacial properties and micro-friction behaviors lead to varying tribological performance in Cu-based composites with MoS₂ during macro-friction tests. Nickel-plated MoS₂ (MoS₂@Ni) exhibits superior lubrication and frictional stability. The friction coefficients of Cu-based composites with MoS₂@Ni under low, medium and high working conditions are 0.36, 0.3 and 0.24, respectively, which are 6%, 12% and 13% lower than those of copper-plated MoS₂ (MoS₂@Cu). Meanwhile, its friction stability is 0.8, 0.6 and 0.58, respectively. With rising braking energy density, wear in Cu-based composites transitions from ploughing to oxidation and then to delamination. Defective MoS₂@Cu/matrix interfaces intensify delamination wear caused by the unstable fracture of subsurface plastic deformation layer cracks at higher energy density. Full article

Structural health monitoring (SHM) technology enables the monitoring and assessment of the condition of various materials and structures. Lamb-guided waves (LW) are widely used to detect damage in large-scale plate structures. One of the parameters used for these purposes is the time-of-flight (ToF) of ultrasonic LW signals. In the presented feasibility study, the ToF was determined based on the idea that the zero-crossings of this signal, filtered by several filters, are concentrated around the maximum of the signal envelope. This ToF detection method, unlike threshold- and peak-based methods, avoids uncertainties in signal and noise levels and does not require a signal detection threshold. Compared to the correlation method, no reference signal is required. It has been established that the curves of signal propagation times with varying distance depend on the group and phase velocities of signal propagation and have phase jumps. The proposed methodology for assessing plate inhomogeneities involves comparing signal propagation time curves with and without damage. This methodology has been verified both through theoretical modeling and experimental research. The experimental studies used a 6 mm thick steel specimen with artificial defects of various diameters (10–35 mm). The A₀ mode of Lamb waves with a central frequency of 150 kHz was excited in the steel plate. For experimentally obtained B-scans, the ToF distributions of signals along the scan trajectories were calculated. By comparing the defective and defect-free ToF curves, critical points of the experimental curves were determined, which were used to estimate the dimensions of the defects. Both in the case of theoretical modeling and in the result of experimental measurements, it was determined that the proposed methodology can be used to determine the inhomogeneities of plates. Full article

Aluminum foam is expected to be applied in various industrial fields as a lightweight, multifunctional material. When it is used as an industrial product, it is essential to form it into the required shape. There have been some attempts to form aluminum foam. However, the formability remains low. In this study, we attempted to form aluminum foam, which was fabricated by heat foaming a precursor, into a flat plate by reheating it above its foaming temperature and then roller forming it. It was found that heating above the foaming temperature and subsequent roller forming enabled the aluminum foam to be formed into a flat plate without causing defects. In a sample in which the precursor was roller-formed immediately after foaming, it was found that compared to the as-foamed aluminum foam, the decrease in porosity was limited to approximately 5%, enabling roller forming while minimizing the influences on pore structures. In samples that were roller-formed after reheating, porosities slightly decreased, but most pores were retained. Even when the aluminum foam was roller-formed to the same thickness as the initial precursor before foaming, the porosities exhibited around 65%, limiting the reduction in porosities to approximately 15% compared to the as-foamed aluminum foam. Full article

Impact-echo/impact response testing is widely used to detect cracks, voids, and delamination, but transient signals and crowded spectra can complicate diagnosis. This study presents a nonlinear, harmonic-based framework that characterizes delamination using higher-order harmonics in the impact-free response, instead of the amplitude-dependent resonance–frequency shift. The delaminated region is formulated as a locally vibrating nonlinear plate/oscillator with polynomial material and geometric nonlinearities, predicting harmonic components whose levels depend on impact intensity and nonlinearity parameters. The approach is validated on a concrete slab containing an artificial delamination, excited by repeatable impacts, and measured with an accelerometer. Frequency-domain analysis shows that intact regions exhibit a distinct spectral pattern, whereas the delaminated region produces a clear fundamental component and, with modestly increased impacts, a strong second harmonic that serves as a defect signature; time series metrics corroborate nonlinearity. The results demonstrate a nondestructive technique that can localize and characterize delamination without driving the specimen into damaging strain. Looking ahead, the same harmonic signature principle can be extended to vibroacoustic/impact monitoring of lithium-ion batteries to flag mechanically induced internal defects (e.g., separator/electrode delamination) that can precipitate internal short circuits and elevate thermal runaway risk, improving quality control and in-service safety. Full article

The surface quality and production efficiency of continuous-casting steel slabs are predominantly determined by the performance of the mold. To address slab corner defects and enhance operational stability, this study systematically optimized two key components: the broad-face clamping mechanism and the narrow-face copper plate. A disk spring–hydraulic composite clamping mechanism was designed and subjected to mechanical analysis to ensure sufficient and reliable clamping force under high-load casting conditions. Meanwhile, based on the principle of solidification shrinkage, an external chamfer structure for the narrow-face copper plate was proposed to improve heat transfer uniformity at the slab corner. Engineering design calculations and practical application in an export-oriented wide-and-heavy slab continuous-casting project (specification: 250 mm × 2500 mm) demonstrated that the optimized clamping mechanism provides enhanced structural rigidity, while the new narrow-face copper plate effectively mitigates corner cracks and reduces wear. This integrated design approach significantly improves slab surface quality and extends component service life, yielding substantial economic benefits. Full article

Aboveground storage tanks are used to store various fluids and chemicals for many industrial purposes. According to API standard 653, the structural integrity of these tanks must be regularly assessed. The U.S. EPA requires each operator to have a Spill Prevention, Control and Countermeasure Plan (SPCC) for aboveground storage containers. The accepted practice for inspection of these tanks, particularly the tank bottoms, requires removing the tank from service, emptying the tank, and interior entry for direct inspection of the structure. The required inspection operations are hazardous due to the chemicals themselves as well as the requirement to operate within confined spaces. An inspection from outside the tank would have significant cost and time benefits and would provide a large reduction in the risks faced by inspection personnel. Guided wave (GW) testing is a promising candidate for screening of storage tank walls and bottoms from the tank exterior due to the ability of GWs to propagate over long distances from a fixed probe location. The lowest-order transverse-motion guided wave modes (e.g., torsional vibrations in pipes) are a good choice for long-range inspection because this mode is not dispersive; therefore, the wave packets do not spread out in time. A common weakness of guided wave inspection is the complexity of report generation in the presence of multiple geometry features in the structure, such as welds, welded plate corners, attachments and so on. In some cases, these features cause generation of non-relevant indications caused by mode conversion. Another significant challenge in applying GW testing is development of probes with high-enough signal amplitudes and relatively small footprints to allow them to be mounted on short tank bottom extensions. In this paper, a new generation of magnetostrictive transducers will be presented. The transducers are based on the reversed Wiedemann effect and can generate shear horizontal mode guided waves over a wide frequency range (20–150 kHz) with SNRs in excess of 50 dB. The recently developed SwRI MST 8 × 8 probe contains an array of eight pairs of individual magnetostrictive transducers (MsTs). The data acquisition hardware allows acquisition using Full Matrix Capture (FMC) and analysis software reporting of anomalies based on Total Focusing Method (TFM) image reconstruction. This novel inspection package allows generation of reports that map out corrosion locations and provide estimates of defect widths. Case studies of this technology on actual storage tank walls and bottoms will be presented together with validation of processing methods on mockups with known anomalies and geometry features. Full article

This study explores the feasibility of using polyurethane (PU) elastomer as a flexible punch-filling medium in cold forming. Microforming processes encounter challenges such as size effects and friction effects, which can lead to defects including fractures, distortions, and central depressions. The proposed method incorporates a high-hardness PU plate (95A) with excellent elasticity and near-incompressibility to address these issues. By compensating for axial compression through lateral expansion, the PU plate distributes pressure uniformly, reduces central stress, mitigates central acceleration effects, and minimizes defects caused by velocity gradients. Experiments and simulations using aluminum alloy Al 1050-O demonstrate that the PU-assisted extrusion–cutting process improves material flow, redistributes forming pressure, and enhances forming stability compared to conventional methods. This approach shows significant potential for advancing microforming technologies, particularly in industries requiring high-precision components. Full article

Steel plate structural integrity is vital for infrastructure and industrial applications, but surface/subsurface defects severely reduce component reliability. Conventional NDT techniques have limitations: Ultrasonic testing is sensitive to surface roughness, eddy current testing lacks deep flaw sensitivity, and vision-based methods are affected by illumination. Although MOI is promising for defect inspection, it faces noisy/low-contrast images and poor feature extraction; existing deep learning models struggle to balance accuracy and real-time performance. Herein, a real-time MOI defect detection framework with deep feature fusion under alternating magnetic excitation is proposed. It uses Pix2Pix cGAN for data augmentation, integrates S-GhostConv for efficient feature extraction, and adopts an improved PANet with attention mechanisms for multiscale fusion. Experiments on real and 6000 synthetic MOI images (four defect types) show it achieves 0.990 mAP0.5 and 130 FPS, outperforming YOLOv8s by 7.1% in accuracy. This framework provides a reliable solution for industrial steel plate defect inspection with broad application prospects. Full article

This first part of a two-part review examines how Computed Tomography(CT)-based, additively manufactured (AM) porous implants are used to reconstruct large segmental defects of the femur and tibia. We focus on lightweight patient-specific lattice implants, architected cages, and modular porous constructs that incorporate engineered porosity into the load-bearing structure and are deployed with plate-, nail-, or external-fixator-based stabilization. We show how defects are described and classified by size, morphology, and anatomical subsegment; how these descriptors influence fixation choice and the resulting mechanical environment; and where along the femur and tibia porous implants have been applied in clinical and preclinical settings. Across the literature, outcomes appear to depend most strongly on defect morphology and local biology, while fixation feasibility and construct behavior vary by subregional anatomy. Most reported constructs use Ti6Al4V porous architectures intended to share load with fixation, reduce stress shielding, and provide a regenerative space for graft and tissue ingrowth. Finite element analyses (FEA) and bench-top studies consistently indicate that lattice architecture, relative density (RD), and fixation concept jointly control stiffness, micromotion, and fatigue-sensitive regions, whereas early animal and human reports describe promising incorporation and functional recovery in selected cases. However, defect descriptors, fixation reporting, boundary conditions, and outcome metrics remain diverse, and explicit quantitative validation of simulations against mechanical or in vivo measurements is uncommon. Most published work relies on simulation and bench testing, with limited reporting of biological endpoints, leaving a validation gap that prevents direct translation. We emphasize the need for standardized defect and fixation descriptors, harmonized mechanical and modeling protocols, and defect-centered datasets that integrate anatomy, mechanics, and longitudinal outcomes. Across the 27 included studies (may be counted in more than one group), simulation and mechanical testing are reported in 19/27 (70%) and 15/27 (56%), respectively, while in vivo studies (preclinical or clinical) account for 9/27 (33%), highlighting a validation gap that limits translation. Part 2 (under review); of these two series review paper; Patient-Specific Lattice Implants for Segmental Femoral and Tibial Reconstruction (Part 2): CT-Based Personalization, Design Workflows, and Validation-A Review; extends this work by detailing CT-to-implant workflows, lattice design strategies, and methodological validation. Full article

The hands-off detection (HOD) function plays a critical role in accurately identifying driver hand contact in advanced driver assistance systems (ADAS), thereby ensuring system reliability and safety compliance. Capacitive touch pads, which are extensively utilized for this purpose, are prone to various defects arising from their manufacturing process. These defects include pad friction, plating anomalies, pattern deformation, surface scratches, and press gaps. Despite their extensive utilization, a systematic methodology capable of detecting both surface-level and internal microstructural defects remains to be established. The present study proposes a capacitance defect detection algorithm grounded in charge quantity (Q) analysis. A dedicated main control board was developed, integrating signal amplification, analog-to-digital conversion, noise filtering, defect classification logic, and real-time visualization through a graphical user interface (GUI). The system was implemented on an operational automotive production line and validated through the inspection of over 240,000 capacitive touch pads under real-world manufacturing conditions. In this setting, the system successfully identified subtle defects that conventional visual inspection methods failed to detect. The proposed method addresses the limitations of traditional inspection techniques and introduces a structured approach to detecting complex defects in capacitive touch sensors. This research is of practical relevance in industrial settings and contributes a systematic framework for future advancements in HOD system reliability and quality assurance. Subsequent research endeavors will investigate the integration of artificial intelligence (AI) and machine learning techniques to facilitate predictive maintenance and intelligent defect management. Full article

Acoustic emission testing is a non-destructive inspection method in which ultrasonic waves emitted by defects in an object are detected and assessed based on their time of arrival and waveform, which strongly depends on the geometry of the object. Those waves appear in different modes with their own velocity and dispersion and different degrees of attenuation can occur for different wave modes. In previous work, a new method for (semi-)automatic recognition of the arrival time of wave modes was presented and validated on a dataset obtained in laboratory conditions on a flat plate. This paper builds upon the previous research and presents a modified method that can be applied to data obtained from an industrial gas storage sphere. The following two wave modes were commonly detected for this sphere: one similar to the zero-order anti-symmetrical mode (A₀) and the other similar to the zero-order symmetrical Lamb mode (S₀) in a plate. The method was adapted to solve the new challenges that were encountered for the sphere. The performance of the adapted automatic mode recognition method was assessed using a dataset with the following four different source types: Hsu–Nielsen sources, sensor pulses, impact by a metallic object and natural sources. The resulting wave mode recognition was compared to manual recognition to determine the rates of successful recognition. The resulting successful recognition rates range from 97% for A₀ and S₀ for Hsu–Nielsen sources down to 73% for A₀ in signals due to natural sources and 74% for A₀ in signals due to impact by a metallic object. Full article

We report on the non-contact characterization of various plate materials (including aluminum and steel) using a high-pressure, micrometer-scale air jet as a broadband ultrasound source and an optomechanical microphone as a receiver. Through-plate transmission spectra are dominated by zero-group-velocity (ZGV) Lamb modes. We attribute this to the ‘point-like’ nature of both the source and receiver, since ZGV modes are spatially localized and comprise a range of non-normal wave numbers. As is well known, the properties of the ZGV modes, including their frequency and amplitude, are sensitive to thickness variations or the presence of defects. The continuous nature and high acoustic power of the gas jet source enabled us to perform uninterrupted scanning of non-uniform steel plates. Given the ubiquitous and low-cost nature of compressed air systems, our approach might be of interest for the rapid inspection of industrial parts. Full article

This study employed cold metal transfer (CMT) welding technology to repair defects in ZL114A aluminum alloy, investigating the influence of key repair welding parameters (preheating temperature, overlap amount, wire feed speed, welding speed) and ultimately obtaining defect-free repaired joints with relatively high tensile strength. Using a single-layer, single-pass bead-on-plate method, the effects of wire feed speed and welding speed on the spreading behavior of ZL114A melt on the substrate surface were studied. Through a two-pass, single-layer welding method, the influence of inter-pass overlap amount on the morphology of overlap welds was investigated. The effects of preheating temperature on the morphology, microstructure, and mechanical properties of the repaired specimens were examined by repair welding experiments on spherical crown grooves. The results indicate that to achieve favorable spreading of ZL114A droplets on the base material surface, the welding speed should be greater than 5 mm/s, and the wire feed speed should be within 7–9 m/min. When the overlap amounts are 65%, 70%, 75%, and 80%, the overlap welds are relatively flat, and lack-of-fusion defects are less likely to occur between the two weld passes. As the preheating temperature increases, the porosity defect rate in the repair weld decreases significantly, and the average grain size in the repair zone shows an increasing trend. The average grain size at the center of the repair weld is larger than that in the fusion zone. When the preheating temperature is 350 °C, no obvious porosity defects are observed in the repair weld. The proportion of high-angle grain boundaries increases significantly, and the maximum Kernel Average Misorientation (KAM) value also increases. The room-temperature tensile strength and Vickers hardness of the repaired specimens are superior to those of the original base material, with the tensile strength increasing by approximately 6 MPa and the Vickers hardness increasing by approximately 4 HV. Full article