Search Results (2,173)

To address concrete cracking in submerged box-shaped hollow thin-walled piers under static ice and hydrostatic pressure, this study proposes a composite strengthening method employing externally bonded steel plates coupled with concrete infill blocks. Based on mechanical theoretical derivation, the strengthened structure is simplified as a cooperative system comprising compression–truss and suspended-cable mechanisms. Key design parameters—including steel plate span, thickness, infill block height, and plate corner configuration—are optimized using a genetic algorithm. The optimization objective minimizes strengthening cost, subject to constraints of concrete crack resistance, steel plate strength, and deformation control, ultimately determining the numerically optimal composite strengthening solution. Validation through planar finite element models demonstrates that: (1) the proposed system effectively suppresses cracking in the original structure; (2) peak stresses in the steel plates remain below the yield strength of Q345 steel; and (3) the theoretical design is reasonable and effective, which can solve the cracking problem of the wading-tank hollow thin-walled pier under the action of surrounding load. Full article

The growing use of weathering steel in bridge engineering has highlighted the increasing impact of fatigue damage caused by the combined effects of welding residual stress and vehicular loading. This study investigates the fatigue performance of Q500qENH weathering steel bridge decks by proposing a coupled analysis method for residual stress and fatigue crack growth, utilizing collaborative simulations with Abaqus 2023 and Franc3D 7.0. An interaction model integrating welding-induced residual stress fields and dynamic vehicular loads is developed to systematically examine crack propagation patterns in critical regions, including the weld toes of the top plate and the weld seams of the U-ribs. The results indicate that the crack propagation rate at the top plate weld toe exhibits the most rapid progression, reaching the critical dimension (two-thirds of plate thickness) at 6.98 million cycles, establishing this location as the most vulnerable failure point. Residual stresses significantly amplify the stress amplitude under tension–compression cyclic loading, with life degradation effects showing 48.9% greater severity compared to pure tensile stress conditions. Furthermore, parametric analysis demonstrates that increasing the top plate thickness to 16 mm effectively retards crack propagation, while wheel load pressures exceeding 1.0 MPa induce nonlinear acceleration of life deterioration. Based on these findings, engineering countermeasures including welding defect control, optimized top plate thickness (≥16 mm), and wheel load pressure limitation (≤1.0 MPa) are proposed, providing theoretical support for fatigue-resistant design and maintenance of weathering steel bridge decks. Full article

To investigate the effect of laser cleaning on the chromium plating of steel tyre moulds, a solid-state laser with an average power of 500 W was used as the cleaning light source. By varying the energy density and the number of pulses applied to the exact location, the changes in the macro- and micro-morphology of the mould surface, surface element content, and chromium plating thickness before and after laser cleaning were studied. The results show that as the laser energy density increases, the cleaning effect improves significantly. However, when the energy density exceeds $1.02\times {10}^4$ mJ/cm², cracks appear in the chrome-plated layer. By changing the number of pulses applied to a specific location, it was found that cracks also appear in the chrome-plated layer when the number of pulses exceeds three. These results provide a reference for the practical application of laser cleaning in the cleaning of chrome-plated steel tyre moulds. Full article

The study presents an analysis of steel-Ultra-High Performance Concrete (UHPC) composite girders. Five composite girder specimens were designed and tested. Analytical strain solutions for the composite girders under asymmetric axial loading were derived using the energy variation method. Results indicate that asymmetric axial forces significantly exacerbate the shear lag effect. Decreasing the width-to-span ratio reduces the shear lag coefficient, while reducing the width-to-depth ratio increases it. The parametric analysis indicates that, under asymmetric axial loading, increasing the strength of the concrete is an effective method to reduce the shear lag effect of the composite girders. Increasing the thickness of the UHPC slab proves to be effective in reducing the shear lag effect. Furthermore, the study indicates that when the b₂/b₁ ratio is less than 1, it has a tiny impact on the shear lag effect; however, when the b₂/b₁ ratio is greater than 1, the shear lag effect becomes more pronounced with increasing b₂/b₁. Additionally, the thickness of the flange plate and web plate of the steel girder has no significant effect on the shear lag effect. The results of the analysis can provide references for similar designs and constructions of composite structures. Full article

Ship repair is hazardous, often presenting unsuitable working areas and risks due to the ship’s configuration. Welding tasks are particularly dangerous due to the high temperatures generated, high enough to melt the metal in structural elements, bulkheads, linings, and tanks. This study investigates the consequences of temperature distribution during the welding of naval plates and proposes some accident prevention measures. Industry working conditions were reproduced, including the materials, procedures, and tools used, as well as the certified personnel employed. DH 36-grade naval steel, with a composition of C max. 0.18%, Mn 0.90–1.60%, P 0.035%, S 0.04%, Si 0.10–0.50%, Ni max 0.4%, Cr max 0.25%, Mo 0.08%, Cu max 0.35%, Cb (Nb) 0.05%, and V 0.1%, was welded via FCAW-G (Gas-Shielded Flux-Cored Arc Welding), selected for this study because it is one of the most widely practiced in the naval industry. The main sensor used in the experiments was an FLIR model E50 thermographic camera, and thermal waxes were employed. The results for each thickness case are presented in both graphical and tabular form to provide accurate and actionable guidelines, prioritizing safety. After studying the butt jointing of naval plates of various thicknesses (8, 10, and 15 mm), safe distances to maintain were proposed to avoid risks in the most unfavorable cases: 350 mm from the welding seam to avoid burn injuries to unprotected areas of the body and 250 mm from the welding seam to avoid producing flammable gases. These numbers are less accurate but easier to remember, which prevents errors in the face of hazards throughout a long working day. Full article

With the rapid expansion of underground rail transit construction in China, the high carbon emissions associated with subway tunnels and stations have become an increasing concern. This study systematically examines the carbon emissions of prefabricated concrete–filled steel pipe columns (PCSPCs) during the construction phase of a Beijing subway station built via the pile beam arch (PBA) method, applying the life cycle assessment (LCA) methodology as a case study. An analytical framework for the synergistic optimization of carbon emissions and costs was developed. By systematically adjusting key design parameters—such as the column diameter, wall thickness, and concrete strength—it was possible to minimize both carbon emissions and project costs while meeting the ultimate load-bearing capacity requirements. The results indicate that the production phase of PCSPCs accounts for as much as 98.845% of total carbon emissions, with labor, materials, and machinery contributing 10.342%, 88.724%, and 0.934%, respectively. A sensitivity analysis revealed that steel plates have the greatest impact on carbon emissions, followed by steel reinforcement, whereas concrete and cement exhibit relatively lower sensitivities. The ultimate load-bearing capacity of PCSPCs increases with larger column diameters, thicker walls, and higher concrete strength grades, with the relationships displaying a nonlinear trend. The damage modes and performance of PCSPCs under different design parameters were further verified through finite element analysis. On the basis of the optimization algorithm used to adjust the design parameters, the carbon emissions and costs of the PCSPCs were reduced by 10.32% and 21.55%, respectively, while still meeting the load-bearing capacity requirements. Full article

Stainless steel welding plays a critical role in industrial manufacturing due to its superior corrosion resistance and structural reliability. The keyhole tungsten inert gas (K-TIG) welding, renowned for its high efficiency, high precision, and cost-effectiveness, demonstrates particular advantages in medium-to-thick plate joining. In order to synergistically leverage the properties of 2205 duplex stainless steel (DSS) and 316L austenitic stainless steel (ASS), we have implemented K-TIG welding with a single variable under control: a constant current and voltage travelling speeds spanning 280–360 mm/min. Defect-free dissimilar joints were consistently achieved within the 280–320 mm/min speed window. The effects of welding speed on microstructural characteristics, mechanical properties, and corrosion behavior of the weld seams were systematically investigated. The percentage of austenite in the weld zone decreases from 84.7% to 59.9% as the welding speed increases. At a welding speed of 280 mm/min, the microstructural features in the regions near the weld seam and fusion zone were investigated. All obtained joints exhibited excellent tensile properties, with their tensile strengths surpassing those of the 316L base metal. The optimal impact toughness of 142 J was achieved at a welding speed of 320 mm/min. The obtained joints exceeded the hardness of TIG joints by 19%. Notably, the grain refinement in the weld zone not only enhanced the hardness of the welded joint but also improved its corrosion resistance. This study provides valuable process references in dissimilar stainless steel K-TIG welding applications. Full article

Sugarcane, a key sugar crop in China, is predominantly manually harvested. In the main sugarcane-producing areas of China, typhoons cause canes to become lodged, resulting in high field losses and low harvesting efficiency. This study aimed to reduce these losses by analyzing the causes: ineffective stalk pickup, transfer, and conveyance. The tests showed the stalk–steel static friction coefficient (SFC) was lower than the stalk–soil SFC. Conventional basecutters use raised patterns to enhance friction, but soil adhesion makes them ineffective, hindering lodged stalk pickup. Bent stalks also struggle to enter butt lift rollers or pass through roller trains, increasing losses. The proposed improvements included adding toothed plates on the cutter discs, optimized disc–roller positioning, and using fewer rollers (one butt lift and one feed roller pair). Theoretical analysis confirmed the toothed plates improved pickup via grabbing force, while using fewer rollers stopped the stalks detaching from and blocking the roller train. A prototype was tested via orthogonal experiments, showing a field loss ratio of 1.21%, a feed rate of 13.09 kg/s, and a billet qualification rate of 95.82% with optimal settings (chopper speed: 390 rpm; 10 stalks/group; roller speed: 230 rpm; ground speed: 1.41 m/s). Field tests achieved 2.0% loss, demonstrating effectiveness for severely lodged cane, a significant improvement over the conventional harvesters (15–20% loss). These findings aid low-loss-level harvester development. Full article

Ti-Mo-N coatings were deposited on GCr15 bearing steel using arc ion plating. The effect of deposition bias on the coating microstructure, mechanical properties, tribological behavior, and electrochemical corrosion resistance was systematically investigated. The coating prepared at −120 V bias showed optimal overall performance. It achieved the lowest friction coefficient (0.308) and lowest wear rate (1.99 × 10⁻⁶ mm³/N·m). The significant improvement in tribological performance is attributed to the lubricating phase formed during the friction process. XPS analysis confirmed the layered MoO₃ formation within the wear scar. Deposition bias also significantly influenced the coating texture. At −120 V, the coating exhibited the strongest (111) crystal plane preferred orientation. This texture strongly correlated with performance enhancement. Regarding electrochemical corrosion, the −120 V coating displayed the lowest corrosion current density (3.62 × 10⁻⁹ A/cm²) and best corrosion resistance. Its corrosion morphology showed no obvious pitting, grooves, or other damage features. The results demonstrate the critical role of deposition bias in tailoring Ti-Mo-N coating properties. This research provides essential experimental support and a theoretical basis for designing wear- and corrosion-resistant protective coatings on bearing steel. Full article

Addressing the issue of stress concentration at the toe of steel plate shear walls, which is susceptible to local buckling and brittle failure under seismic loading, this paper innovatively proposes a disc spring-laminated rubber energy dissipation device (DSLRDD) newly designed for application at the wall toe of the shear wall structures. Firstly, the structure characteristics and energy dissipation principle of the DSLRDD are described. Secondly, the finite element model of the DSLRDD is established in ABAQUS. Furthermore, the optimal design parameters’ values of DSLRDD are analyzed and given by taking the stacking arrangement of disc springs, the thickness ratio of steel plate to rubber layer, and the yield strength of steel plate as three main parameters. It is recommended that in DSLRDD, the disc spring stacking arrangement adopts either two pieces in series or a composite of series–parallel. At the same time, the range of the thickness ratio between the steel plate and the rubber layer is defined as being between 1.25 and 2.5, and the yield strength value of the steel plate is determined as 400 MPa. Finally, to verify the energy dissipation capacity of the DSLRDD, a double corrugated steel plate shear wall (DCSPSW) is taken as the experimental structure. The model has been verified against the test data, with a maximum damping force error of 14.4%, ensuring reliable modeling. DSLRDD models with the disc spring stacking arrangements of two pieces in series and composite of series–parallel were established, respectively, and they were installed at the toe of the DCSPSW. The seismic performance of the DCSPSW before and after the installation of two different DSLRDDs is studied. The results show that the DSLRDDs have obvious energy absorption capabilities. The energy dissipation factors of DCSPSW before and after installing DSLRDD were increased by 10.0% and 8.9%, respectively. DCSPSW with DSLRDD exhibits better plasticity and bearing capacity under seismic action, and the stress and deformation are mainly concentrated on the DSLRDD instead of the wall toe. Moreover, it is recommended to use the stacking arrangement of two series disc springs with a simple structure. In conclusion, the DSLRDD has excellent energy dissipation capacity and can be fully applied to practical projects. Full article

A common technique used in factories to shape metal panels is shot peen forming, where the panel is sprayed with a high-velocity stream of small steel pellets called “shot.” The impacts between the hard steel shot and the softer metal of the panel cause localized plastic deformation, which is used to improve the fatigue properties of the material’s surface. The residual stress distribution imparted by impacts also results in bending, which suggests that a torque is associated with it. In this paper, we model shot peen forming as the application of spatially varying torques to a Kirchhoff plate, opting to use the language of thermoelasticity in order to introduce these torque distributions. First, we derive the governing equations for the thermoelastic thin plate model and show that only a torque-type resultant of the temperature distribution shows up in the bending equation. Next, to calibrate from the shot peen operation, an empirical “effective torque” parameter used in the thermoelastic model, a simple and non-invasive test is devised. This test relies only on measuring the maximum displacement of a uniformly shot peened plate as opposed to characterizing the residual stress distribution. After discussing how to handle the unconventional fully free boundary conditions germane to shot peened plates, we introduce an approach to solving the inverse problem whereby the peening distribution required to obtain a specified plate contour can be obtained. Given that the relation between shot peen distributions and bending displacements at a finite set of points is non-unique, we explore a regularization of the inverse problem which gives rise to shot peen distributions that match the capabilities of equipment in the factory. In order to validate our proposed model, an experiment with quantified uncertainty is designed and carried out which investigates the agreement between the predictions of the calibrated model and real shot peen-forming operations. Full article

To address the decline in the localization accuracy of magnetic adhesion wall-climbing robots operating on large steel structures, caused by visual occlusion, sensor drift, and environmental interference, this study proposes a simulation-based multi-sensor fusion localization method that integrates an Inertial Measurement Unit (IMU), Wheel Odometry (Odom), and Ultra-Wideband (UWB). An Extended Kalman Filter (EKF) is employed to integrate IMU and Odom measurements through a complementary filtering model, while a geometric residual-based weighting mechanism is introduced to optimize raw UWB ranging data. This enhances the accuracy and robustness of both the prediction and observation stages. All evaluations were conducted in a simulated environment, including scenarios on flat plates and spherical tank-shaped steel surfaces. The proposed method maintained a maximum localization error within 5 cm in both linear and closed-loop trajectories and achieved over 30% improvement in horizontal accuracy compared to baseline EKF-based approaches. The system exhibited consistent localization performance across varying surface geometries, providing technical support for robotic operations on large steel infrastructures. Full article

The kinetics and evolution of hydrogen-induced cracking (HIC) were modeled using a theoretical model developed by Gonzalez to calculate the individual crack growth rate and a computational algorithm based on a Poisson distribution to generate the initial spatial distribution of HIC nuclei. Additionally, the Monte Carlo method was used to model the interconnection of individual HIC cracks. The results of the computational model were compared versus experimental results of HIC induced by cathodic charging experiments in low-carbon steel plates. The model was capable of accurately emulating the kinetics of HIC, considering the first stage of nucleation and growth of randomly dispersed individual HIC cracks, followed by a second stage where the individual cracks interconnect with each other to form large cracks that subsequently grow. The study was complemented with the fractographic examination of the HIC cracks to verify if the fracture mechanism is consistent with the crack morphology and propagation mode in the proposed model. The results indicate that HIC propagation occurs by cleavage and quasi-cleavage mechanisms, with crack interconnection by ductile shear tearing, where the driving force for HIC is the accumulated hydrogen pressure within the internal HIC cracks, explaining why the crack growth rates are nearly constant in each stage of HIC growth. Full article

In the steel manufacturing process, defect classification is a critical step to ensure product performance and safety. However, due to the complexity of defect types and their multi-scale distribution characteristics, surface defect classification for steel plates remains a significant challenge. To address this issue, this paper proposes a deep learning model based on the ConvNeXt architecture, FAX-Net, which is designed to further improve the accuracy of steel surface defect classification. The FAX-Net architecture incorporates a Symmetric Dual-dimensional Attention Module (SDAM), which employs structurally symmetric and parallel modeling paths to effectively enhance the model’s responsiveness to critical defect regions. In addition, a Transformer-Fused Feature Pyramid Network (TF-FPN) is designed by integrating a lightweight Transformer to improve information interaction and integration across features of different scales, thereby enhancing the model’s discriminative capability in multi-scale scenarios. Experimental results demonstrate that the proposed FAX-Net model offers significant advantages in steel surface defect classification tasks. On the NEU-CLS dataset, FAX-Net achieves a classification accuracy of 97.78%, outperforming existing mainstream methods. These findings validate that FAX-Net possesses superior classification capabilities and is well-suited to handle a wide variety of defect types and scales effectively. Full article

It is an urgent issue for preventing slope failure caused by increasingly severe earthquakes and heavy rain. As a conventional construction method, reinforcing bar insertion work uses the tensile force of the core bar to integrate multiple core bars and pressure plates. Meanwhile, landslide deterrence piles are a construction method in which steel or concrete piles are constructed below the slope, and the rigidity of the piles is used to resist slope failure. In this study, these methods are combined to propose a reinforcing bar insertion work that uses pipes as a construction method. The pipes are not embedded in the immovable layer and are not connected to the reinforcing bar insertion work; therefore, the construction is expected to be simple. Two series of model experiments—a lift-up experiment and a water sprinkling experiment—were performed. Through the lift-up experiment, the effectiveness of the proposed method against static load was confirmed, and the evaluation formula of the load applied to the core bar was proposed. Through the water sprinkling experiment, the effectiveness against rainfall was confirmed, that is, the time until slope failure was extended by the proposed method. Full article