Search Results (191)

Industrial sensor studies often report controlled defects or isolated field events without preserving the commissioning evidence that connects them. This retrospective single-site study evaluates an optical conveyor-belt monitoring system through technical assessment, industrial and belt-loop tests, control-system integration, six investigation groups, and one field-confirmed edge tear. The installation used upper and lower optical camera subsystems with embedded processing, proprietary internal confirmation logic, industrial communication, and connection to the plant programmable logic controller (PLC). Repeated passages of the same defects were treated as non-independent descriptive observations. Among the quantified configurations, scenario-specific descriptive PLC-output proportions ranged from 20.0% for an approximately 0.20-mm nearly closed central slit to 96.0% for a 6-mm V-shaped opening. Fourteen protection-output assertions were assigned to six investigations. Corrective observation preceded re-interlocking on 7 August. On 31 October, the edge-tear indication reached the configured protective-stop state and caused an automatic conveyor stop; inspection confirmed the edge tear, and maintenance repaired the belt. The case demonstrates why camera-interface recognition, confirmed output, plant action, and field confirmation must be reported separately. Internal optical calculations, confirmation parameters, software implementation, configuration details, and decision logic remain proprietary. Full article

This paper presents a method for monitoring damage evolution at sandstone-binding material interfaces by combining a Vision Transformer (ViT) deep learning model with piezoelectric ultrasonic monitoring. Direct shear tests were conducted on bonded weak sandstone specimens. The results indicate that the damage evolution process can be divided into four stages: initial elastic, compaction and stabilization, crack propagation and coalescence, and frictional sliding and interlocking. Ultrasonic signals acquired during loading reveal that interface damage evolution is in good agreement with the time-domain waveforms, Continuous Wavelet Transform (CWT) time–frequency spectra, and wavelet packet energy. Based on the ViT-Small/16 backbone, a ViT model with adaptive frequency-feature extraction was developed for small-sample and cross-specimen interfacial damage-stage identification, using the Stage I health observations of each specimen prior to loading as the reference. Results from five repeated runs with different random seeds show that the method achieved an accuracy of 93.23% ± 0.72% and an F1-score of 92.32% ± 0.90%, demonstrating favorable recognition performance and stability under the current condition. This study offers insights into the damage monitoring and subsequent warning of similar binary interfaces in tunnel engineering, geotechnical engineering, and stone cultural heritage conservation. Full article

Grouted anchors made of glass fiber-reinforced polymer (GFRP) have gained popularity in cold-region construction projects, primarily owing to their resistance to corrosion and low density. Although prior research has addressed the bond–slip characteristics of FRP-to-concrete joints, a theoretical formulation that links cumulative freeze–thaw damage of the mortar matrix to the progressive loss of bond strength at the GFRP bar–mortar interface is still lacking. This work provides a combined experimental and theoretical examination of how the bonding capacity of ribbed GFRP bars in cement mortar declines after 0, 30, 60, and 90 FTCs. Compression and splitting tension tests were carried out on mortar cubes, while pullout specimens were used to assess the interfacial bond strength. Two mortar grades commonly used in anchorage practice (M25 and M35) and two bar diameters (12 mm and 16 mm) were selected as test variables. After 90 FTCs, the maximum bond strength fell by as much as 64.1%, whereas the post-peak residual bond strength suffered an even more pronounced drop of up to 79.3%. Meanwhile, the residual-to-peak-bond-strength ratio decreased steadily with the number of FTCs, marking a shift from a mechanically interlocked interface to a friction-governed one. The higher-grade mortar (M35) experienced clearly superior resistance to freeze–thaw attack compared to M25, while the larger-diameter bars (16 mm) degraded faster. An analytical model for estimating the bond-strength degradation is proposed, where an exponential environmental factor was introduced and the decay constants were calibrated via nonlinear regression against the bond-strength retention ratios at 0, 30, 60, and 90 FTCs. The proposed models are calibrated empirical relationships that reproduce the measured degradation well within the tested parameter ranges and indicate reasonable internal stability under leave-one-group-out cross-validation. This study provides two theoretical provisions: the freeze–thaw degradation of the GFRP–mortar bond can be effectively described by a single exponential damage law whose decay constant quantifies the rate at which the interfacial capacity is exhausted, and the residual-to-peak-bond-strength ratio serves as a mechanistic indicator of the transition from mechanical interlock to friction-controlled failure. These provisions quantitatively link mortar degradation to interfacial capacity loss, thereby providing a theoretical basis for durability design of GFRP grouted anchors in cold regions. Full article

Large-area three-dimensional polyjet printing (3DPP) of continuous photopolymer laminates directly onto knitted fabrics provides a potential route toward technical textile applications beyond localized decorative features. This study investigated acrylic photosensitive resin (APR) laminates measuring 330 × 432 mm deposited onto a Nylon 66 interlock-knitted fabric. 12- and 20-layer laminates were produced in one-sided and two-sided configurations, and their morphology and tensile behavior were evaluated in the wale and course directions before and after 20 h of accelerated xenon-arc weathering. Scanning electron microscopy (SEM) showed a continuous external APR layer with localized resin entry into inter-yarn and inter-filament spaces, indicating a form-fitting physical connection between the resin and the knitted structure; interfacial strength was not measured. Before weathering, the 20-layer two-sided (20L-2S) architecture exhibited the highest maximum engineering stress, reaching 13.11 ± 0.37 MPa in the wale direction and 7.44 ± 0.28 MPa in the course direction. In contrast, the 20-layer one-sided (20L-1S) architecture retained substantially greater extensibility, reaching maximum engineering strains of 183.94 ± 2.45% and 217.34 ± 2.88% in the wale and course directions, respectively. Thus, two-sided printing maximized load-bearing capacity, whereas one-sided 20-layer printing provided a better balance between reinforcement and preservation of the large-strain response of the knitted substrate. Accelerated weathering reduced the maximum engineering stress of fabric-supported laminates by 5.4–18.7% and maximum engineering strain by 2.1–21.1%, depending on architecture and loading direction. Unsupported APR laminates exhibited 59.9–77.2% increases in maximum engineering stress after exposure, without a corresponding increase in strain capacity. The contrasting response is consistent with APR post-curing or stiffening combined with reduced Nylon 66 extensibility, although chemical and interface-specific tests are required to distinguish these mechanisms. The results demonstrate that continuous 3DPP can produce mechanically integrated textile–photopolymer laminates with tunable strength–extensibility relationships relevant to flexible technical textile structures. Full article

The structural use of three-dimensional concrete printing remains limited by the directional weakness introduced during extrusion and layer-by-layer deposition. Although 3DPC offers major advantages in formwork elimination, architectural freedom, and automated construction, its printed architecture produces interfaces, pore networks, and reinforcement discontinuities that do not exist in the same form in conventionally cast concrete. This review examines the anisotropic behavior of 3DPC by linking its architectural arrangement, physical interlayer mechanisms, and chemical durability-related processes. The analysis shows that anisotropy develops from the combined effects of filament orientation, interlayer bonding quality, pore morphology, cold-joint formation, mechanical interlocking, hydration continuity, and reinforcement limitations. Weak interlayer regions act not only as preferred paths for crack initiation and propagation under tensile, flexural, shear, and compressive loading, but also as transport channels that accelerate water absorption, chloride ingress, carbonation, sulfate attack, and freeze–thaw deterioration. The review further highlights that fiber, textile, FRP, and discrete reinforcement strategies can reduce some consequences of anisotropy, but their effectiveness depends on whether they bridge the weaker interlayer regions rather than merely reinforcing the filament direction. SEM-based observations confirm that microstructural discontinuities, fiber-matrix debonding, irregular hydration products, and connected pores provide the material-level basis for the directional response of printed concrete. Overall, anisotropy should be treated as a design-critical feature of 3DPC rather than as a secondary defect. Reliable structural application requires coordinated control of mixture rheology, deposition parameters, interlayer timing, curing, toolpath design, and reinforcement layout. Full article

The viscosity peak phenomenon at the phase inversion point in crude oil emulsions can be understood through the lens of physical gelation. This study employs coarse-grained molecular dynamics (CG-MD) simulations to investigate the gel-like network structures formed at oil–water interfaces across varying water-to-oil particle-number ratios. We reveal that pure water forms a fully connected hydrogen bond network (500 molecules, 313.15 K, 2.68 H-bonds per molecule) behaving as a flexible physical gel scaffold, while pure oil exhibits a dispersed sol-like structure (35.9 clusters average). At the phase inversion point (50% water cut), the water network fragments into 44 gel-like clusters (193 network bonds) while oil forms 76 small clusters acting as physical crosslinking nodes embedded within the water network voids. This creates an interlocked gel structure with a maximum Interlocking Index (LI_CG = 36.67), directly corresponding to the viscosity peak. At 30% water cut, a W/O morphology with (LI_CG = 22.17) represents a weaker gel state. We demonstrate that gel rigidity rather than network existence determines macroscopic viscosity, with $LI$ serving as an effective crosslinking density metric. Model parameters calibrated via differential evolution optimization against experimental data from three oil wells yield $R^2=0.94$. This work provides a molecular mechanism revealing the flexible-network-to-rigid-gel transition as the origin of emulsion viscosity peaks, offering a gel-science perspective on emulsion rheology control in petroleum engineering. Full article

To investigate the influence of tailings content between geotextile layers in tailings dams built with geotextile bags on interfacial shear behavior and dam stability, direct shear tests were conducted to examine the shear mechanical properties of the geotextile interfaces under different tailings water contents (20%, 30%) and different tailings contents per unit area between geotextile layers (0, 0.0125, 0.0250, 0.0500 g/cm²). Based on the distribution patterns of tailings particles at the shear plane, the interface shear mechanism was elucidated, and the influence of interlayer tailings content on the stability of the tailings dam built with geotextile bags was analyzed using the discontinuous–continuous coupling method. The results show that, under the tested material properties and experimental conditions, both the peak shear stress and the interfacial friction angle first increased and then decreased with increasing tailings content between geotextile layers, reaching their maximum values when the tailings content was 0.0250 g/cm², while the cohesion exhibited the opposite trend. An appropriate amount of tailings particles embedded in the pores of the geotextile enhances the mechanical interlock between the particles and the geotextile, thereby improving the shear resistance at the interface. When the tailings content was excessively high, a loose tailings layer formed at the interface, shifting the shear plane into the tailings and, consequently, reducing the interface shear strength. Under the tested conditions, the safety factor of the dam first increased and then decreased as the tailings content between geotextile layers increased, reaching its highest value at a tailings content of 0.0250 g/cm², which was approximately 14.3% higher than under conditions without tailings. When the tailings content increased to 0.0500 g/cm², the safety factor of the dam decreased. This research provides a theoretical basis for quality control in the construction of tailings dams built with geotextile bags and the design of geotextile interfaces under conditions comparable to those investigated in this study. Full article

The sturdy and stable unique polyhedral structure of FeOOH nanoparticles facilitates stress and load transfer, thereby forming a tighter mechanical interlock at the carbon fiber–matrix interface. In this work, the FeOOH nanocrystal layer in situ grown on flexible carbon fiber cloth was rationally designed and fabricated through hydrothermal synthesis. Then, the non-covalent cation–π bond was constructed at the interface between the iron ion-loaded FeOOH nanoparticles and indole-based poly(hexahydrotriazine) (In-PHT). Owing to the collaborative effects of physical anchoring and chemical bonding, the resultant composite exhibited an outstanding tensile strength of 322 MPa, and the friction coefficient significantly decreased by 63% compared with the composites without FeOOH nanoparticles. Moreover, the resultant worn composite showed an excellent self-healing property owing to the introduction of polyethylene wax (PEW) with a low melting point, and the healed friction coefficient remained almost unchanged. Extensive analyses verify that the phase-separated structure and Fe³⁺–π interactions across multiscale interfaces achieve the combined advantages of wear resistance and durability for recyclable carbon fiber-reinforced poly(hexahydrotriazine) composites (PHT-CFRPs). Full article

Natural biological materials achieve synergistic strengthening and toughening through soft–stiff dual-phase architectures, inspiring artificial composites. Despite extensive studies on individual bio-inspired designs, systematic comparative investigations under fully unified experimental conditions remain limited. Here, five representative bio-inspired composite structures (brick–mud, cross-lamellar, interlock, overlap, and concentric) are fabricated via 3D printing and compared under quasi-static three-point bending. Key mechanical parameters—including flexural modulus, flexural strength, crack-initiation displacement, effective fracture displacement, total energy absorption, and post-peak energy dissipation ratio—are derived from force–displacement curves, complemented by high-resolution imaging of crack paths, crack front morphologies, and fracture surfaces. The concentric structure exhibits the highest flexural modulus and flexural strength, yet fails catastrophically with only a 9.95% post-peak energy dissipation ratio. The brick–mud and cross-lamellar structures achieve the highest post-peak energy dissipation ratios (27.69% and 27.42%, respectively), which may be attributed to crack deflection and interfacial debonding, yet at the cost of low flexural strength. The interlock structure, apparently lacking effective deflecting interfaces, shows straight-through propagation and brittle behavior. In contrast, the overlap structure appears to benefit from sustained crack deflection along inclined interfaces, thereby providing a balanced combination of high flexural strength, large deformability, and moderate energy absorption, demonstrating the best overall mechanical performance. Full article

Interlocking permeable pavements (IPPs) are increasingly adopted within sustainable urban drainage systems to reduce runoff, improve water quality, and strengthen climate-resilient urban infrastructure. However, clogging remains the principal constraint on their long-term hydraulic performance and wider implementation. This review synthesises current evidence on clogging mechanisms, hydraulic decline, and lifecycle mitigation strategies for permeable interlocking concrete pavements (PICPs), concrete grid pavements (CGPs), and plastic grid pavers (PGPs). The literature is dominated by PICP studies, with CGP and PGP underrepresented, restricting typology-specific assessment. Sediment accumulation within joints, grid openings, bedding layers, and near-surface interfaces is consistently identified as the primary clogging mechanism, while traffic, rainfall-runoff loading, biological processes, pollutant retention, and sediment inputs from adjacent impervious surfaces further influence hydraulic deterioration. The findings indicate that hydraulic performance is influenced not only by pavement age but also by interactions among pavement design, filler or joint material, drainage configuration, construction quality, sediment exposure, monitoring, and maintenance. Effective mitigation therefore requires lifecycle management, encompassing source control, pretreatment, appropriate material selection, construction quality assurance, routine hydraulic monitoring, and timely preventive and restorative maintenance. Future research should prioritise standardised clogging assessment protocols, improved laboratory–field integration, targeted investigation of CGP and PGP, biological and pollutant-linked clogging processes, climate-driven rainfall extremes, and decision-support. Full article

The dissimilar combination of NiTi shape memory alloy and Ti6Al4V titanium alloy offers superelasticity, biocompatibility and high specific strength, showing broad application prospects in aerospace and medical fields. However, when fabricating NiTi/Ti6Al4V composite components by multi-material laser powder bed fusion (MM-LPBF), brittle cracks or even complete delamination easily occur at the interface. In this paper, without relying on intermediate interlayer materials, we innovatively propose a root-inspired three-dimensional bio-interlocking interface structure. By means of macroscopic three-dimensional geometric interlocking, the crack propagation path and load transfer mode are forced to change. Using the branching angle (45°, 60°) and the structural size multiplier (1.2, 1.5) as variables, the influence of the bio-inspired geometric parameters on the interfacial forming quality, microstructure and mechanical properties was systematically investigated. The results show that the branching angle is the primary factor determining the performance. The 45° low-angle branched specimens exhibit overall brittle delamination along the flat metallurgical reaction interface under shear loading, with an average shear strength of only 17.47 MPa. In contrast, the 60° high-angle branched specimens, owing to their larger normal embedding depth, exhibit a failure mode transitioning to a mixed mode that includes crack deflection, branch shearing and plastic tearing of the Ti6Al4V matrix. Although TEM confirms that a continuous Ti₂Ni brittle phase still exists at the interface, the optimised 60–1.5 structure increases the average shear strength to 128.37 MPa, which is more than six times higher than that of the 45–1.2 group (17.47 MPa). This “geometrical constraint toughening” strategy provides a new paradigm for the interfacial strengthening of dissimilar metals without relying on metallurgical modification. Full article

Interfaces at multiple scales within rocks critically control the mechanical properties of rock masses. However, the mechanisms by which interface roughness characteristics affect non-plastic deformation remain incompletely understood. In this study, particle-flow simulations were used to conduct loading–unloading tests on rough interfaces. The results show that contact surfaces inclined relative to the overall interface provide additional resistance during unloading and recovery, thereby increasing both the magnitude and likelihood of interfacial hysteresis. This mechanism explains why hysteresis can occur under loading normal to the interface. Differences between the static and dynamic friction coefficients, together with dynamic changes in the normal vectors of the contact surfaces, further intensify the hysteretic response. When deformation of the surrounding material is considered, the “lateral compression–expansion effect” caused by asperity extrusion and interlocking under compression, as well as the slip-induced “dilatancy effect,” also contributes substantially to rough-interface hysteresis. In addition, initial stress on crack surfaces can enhance the degree of hysteresis. The grain-based rock model incorporating interface roughness and in situ stress effectively reproduces the non-plastic hysteretic behavior of rocks. Full article

A novel assembled integral multi-ribbed composite floor system consisting of precast panels and a cast in situ topping has previously been validated through full-scale one-way and two-way slab experiments. Although the global load capacity of the system was initially verified, the experiments reveal that the concrete-to-concrete interfacial behavior between the precast panel and the cast in situ topping is a critical factor governing internal force redistribution and its post-cracking performance. To uncover the governing interfacial mechanism, this study develops a refined three-dimensional nonlinear finite element model using a coupled cohesive–frictional interface interaction, where a surface-based cohesive interaction captures the initial interfacial debonding and a penalty-based Coulomb friction model describes the subsequent shear-slip behavior. The model reproduces the cracking patterns, load-deflection relationship, and failure modes, with the relative error of load capacity, initial stiffness and crack load all less than 15%. Parametric analyses further indicate that the interfacial shear-transfer mechanism governs post-cracking stress redistribution across the multi-ribbed section, preventing premature delamination and ensuring efficient mobilization of the section’s flexural resistance. To effectively restrain this interfacial slip, an improved shear-key configuration is proposed to activate an enhanced mechanical interlocking mechanism. Numerical results confirm that the improved configuration effectively suppresses macro-sliding and redistributes local stress concentrations, thereby enhancing the structural integrity and flexural efficiency of precast composite floor systems. Full article

Clayey soils are generally characterized with low strength and high plasticity which may affect the stability of the subgrade in road infrastructure and hence encourage research into sustainable stabilization techniques. The objective of this study was to investigate the possibility of using recycled crumb rubber (CR) mixed with biaxial geogrid reinforcement to enhance the engineering performance and interface shear behaviour of problematic clayey soil. The experiments were performed on biaxial geogrid BX1100, waste crumb rubber, clay subgrade soil, type B subbase granular material and other materials. The subgrade soil of clay has been collected from the airport area of Al-Muthanna region, Baghdad. An extensive programme of laboratory tests was conducted on soil mixtures with 5%, 10% and 15% of crumb rubber (CR) and untreated soil to determine the effect of stabilization with crumb rubber. The protocol consisted of Atterberg limits, modified Proctor compaction, California Bearing Ratio (CBR) and large-scale direct shear testing. The results showed that the engineering properties of the clay soil were improved by using CR. Maximum improvement was observed at 15% CR content where CBR increased by 56.6% and plasticity index decreased by 44% over the untreated soil. In addition, the large-scale direct shear tests showed that the interface shear strength increased with increasing CR content under geogrid reinforcement. The calculated interaction coefficients were greater than unity for all the tested mixtures indicating effective bonding and interlocking between the reinforced soil layers. The results indicate that the synergistic effect of CR and geogrid reinforcement could improve the interface behaviour of the weak clay subgrade soils with sustainable reuse of waste tyre rubber. Full article

Additive manufacturing has evolved beyond monomaterial fabrication, enabling the integration of dissimilar polymers within a single structure to achieve spatially tailored properties. In Fused Filament Fabrication (FFF), however, the discrete, layer-wise deposition and inherent material incompatibilities make the interfacial region a critical determinant of structural integrity. Rather than acting as a simple boundary, the interface governs stress transfer, damage initiation, and failure propagation, especially in biodegradable polymer systems where thermal and rheological mismatches are pronounced. This study investigates bi-component FFF structures manufactured from PLA and PLA/PHA using mechanically interlocked interface geometries (T-type and dovetail configurations). Mechanical performance was assessed through tensile, flexural, and Charpy impact testing, complemented by fracture analysis, surface topography evaluation, and X-ray Computed Tomography (XCT) for internal defect characterization. The results establish correlations between interface design, defect distribution, and overall structural response. Full article