Search Results (1,127)

Masonry arch bridges are critical assets in aging transportation networks, yet their Structural Health Monitoring (SHM) remains challenging. Smart bricks—piezoresistive sensing units compatible with masonry structures and capable of acting simultaneously as load-bearing components and strain sensors—offer a promising solution for embedding self-sensing capability directly within the masonry. While previous work by the authors has investigated their use in masonry walls, their application to arched structures remains unexplored. This gap is particularly significant given that arches, characterized by a predominantly compressive stress state, represent a natural context for smart-brick implementation. This study presents a numerical investigation assessing the potential of smart bricks for strain-based SHM of masonry arch bridges. A Finite Element (FE) model, derived from a validated experimental benchmark representative of typical Italian railway arch bridges, was used to virtually embed smart bricks at selected cross-sections along the arch. Damage progression was simulated through cyclic loading–unloading stages, enabling direct correlation between strain evolution and structural deterioration. Results demonstrate that smart bricks accurately capture damage-driven strain redistributions, closely mirroring both the sequence of damage formation and the associated collapse mechanism. These findings support the use of smart bricks for early detection of localized structural changes in masonry arches, providing a foundation for future experimental validation and real-world deployment of minimally invasive SHM systems. Full article

Shot peening is widely used to improve fatigue performance by introducing compressive residual stresses, but the influence of very high coverage levels on medium carbon steels such as AISI 4140 remains unclear. This work investigates conventional and severe shot peening at 100%, 400%, 1000%, and 1500% coverage under a fixed 18A Almen intensity, combining rotating-bending fatigue experiments with a finite element cell (FE-Cell) approach for residual stress quantification. Fatigue tests were conducted at stress amplitudes of 37 MPa, 40.5 MPa, and 44 MPa, supported by surface roughness, hardness, and fractographic characterization. The results show a strong coverage–stress interaction: at 37 MPa, severe shot peening at 1000% coverage yields the maximum fatigue life improvement, whereas at 44 MPa the optimum shifts to 400% coverage, and excessive coverage (1500%) produces over-peening, microcrack networks, and reduced life. FE-Cell simulations reveal that increasing coverage deepens and intensifies compressive residual stresses but also promotes stress redistribution at extreme coverage. The combined findings define an optimal processing window of 400–1000% coverage for AISI 4140, balancing deep compressive residual stresses with controlled surface integrity and providing practical guidelines for industrial severe shot peening of rotating components. Full article

This study proposes a comprehensive methodology for the experimental characterization and non-linear dynamic modelling of Polycrystalline Diamond (PCD) bearings, establishing a high-fidelity digital twin approach for the condition monitoring of rotating machinery. The research addresses complex rotor–stator interactions through the development of a multibody numerical framework. A structural 1D Finite Element (FE) model of the stator assembly was first calibrated via experimental modal analysis, achieving a high correlation with the first four bending modes and a maximum frequency discrepancy of only 1.4%. This validated structure was integrated into a non-linear multibody environment to simulate transient rub-impact events at rotational speeds up to 5500 rpm across varying clearance configurations. The model successfully captures the transition from stable periodic orbital motion to the stochastic and chaotic regimes observed in high-clearance setups. Frequency-domain validation further confirms the model’s accuracy in identifying supersynchronous harmonics and energy distribution patterns. Quantitative analysis shows that high-clearance configurations generate impact forces exceeding 6000 N, providing critical data for structural health assessment. These results demonstrate that the proposed digital twin serves as a robust physical foundation for diagnostic systems, enabling the identification of contact-induced vibrational signatures that are essential for training prognostic algorithms. This approach facilitates the autonomous monitoring of critical rotating machinery in demanding industrial and subsea applications, supporting the transition toward active balancing and model-based vibration control strategies. Full article

TC4DT (ELI) is a damage-tolerant titanium alloy characterized by high fracture toughness and slow crack propagation rates, and is, therefore, considered one of the standard materials for model fasteners in modern equipment. However, its high yield strength leads to excessive tool wear and forming defects. This paper presents a complete FE simulation framework to investigate the thread-rolling process of TC4DT(ELI) bolts M16 × 1.5. Using the actual geometries of the workpiece and rollers, an elasto-plastic three-dimensional finite element model was built in ABAQUS/Explicit to perform verification simulations, with the theoretical blank diameter and forming force as the reference benchmarks. The simulation results agreed well with the actual industrial data. This study carried out single-factor analyses of the effect of three important process parameters—the roll speed, friction coefficient, and initial temperature—on the resulting stress–strain distribution, forming force, and thread formation depth. A modal analysis was performed in ANSYS Workbench to check the structural integrity and avoid resonance while operating. According to the results, the optimized parameters decreased the maximum forming force by 14.8% and improved thread filling. Compared with experimental data, the simulation error in the blank diameter was controlled within 1.2%. The present work, a reliable numerical underpinning for replacing expensive and time-consuming trial-and-error processes, forms a basis for high-performance titanium alloy fasteners and assists in the wider application of such fasteners in modern equipment and any advanced manufacturing industries. Full article

With the increasing application of the Vertical Shaft Machine (VSM) method in ultra-deep shafts, accurate prediction of construction-induced structural stresses is vital for engineering safety. Currently, VSM is predominantly used in soft soils, where structural response analysis still relies on finite element (FE) simulations that are computationally intensive and complex to model. To improve analysis efficiency and understand the structural behavior of VSM shafts in granite composite strata, this study takes the first VSM shaft project in South China—the Guangzhou–Huadu Intercity Railway Shield Shaft—as a case study. A “monitoring-driven, large-sample data, machine learning substitution” framework is proposed for predicting structural stresses during construction. The framework calibrates an FE model using monitoring data. Through full factorial design, key design parameters—including main reinforcement diameter, stirrup diameter, concrete strength grade, and steel plate thickness—are systematically varied. Parametric FE simulations are then conducted to construct large-sample response databases (540 sets for ring 0 and 864 sets for the cutting edge ring). Genetic algorithm is introduced to optimize the hyperparameters of Random Forest, XGBoost, and Neural Network models, and their predictive performances are systematically compared. Results show that the proposed framework effectively substitutes traditional FE analysis and enables rapid multi-parameter comparison. Among the models, GA-XGBoost achieves the highest prediction accuracy across all stress indicators (R² > 0.999, where R² is the coefficient of determination, with values closer to 1 indicating better predictive performance), demonstrating the superiority of its gradient boosting and regularization mechanisms in handling tabular data with strong physical correlations. Moreover, the method exhibits good extensibility to other engineering response predictions beyond construction stresses. Full article

Weight reduction and dynamic performance optimization are critical for airborne direct-drive VICTS satellite communication antennas, which require lightweight, high-speed, and high-precision rotation. Traditional vibration suppression methods, such as uniform support layout and added damping, rely heavily on empirical trial and error, lack targeted modal control, and cannot balance lightweight design with dynamic stiffness. To address these issues, this paper proposes a wave-theory-based dynamic modeling and rapid optimization method for multi-layer rotating components in direct-drive VICTS antennas. The kinematic model of the rotating ring and ball revolution excitation are derived using the annular wave equation and bearing kinematics. A Modal Blocking Mechanism is established: placing support balls at positions satisfying the half-wavelength constraint suppresses target mode shapes via wave interference, achieving vibration attenuation at the source. A homogenization equivalent method based on RVE is developed for irregular cross-section rings, yielding analytical expressions for in-plane equivalent elastic modulus and out-of-plane equivalent shear modulus. These parameters are integrated into the wave equation to analytically solve vibration modes, avoiding iterative finite element computations. A rapid multi-objective optimization framework is then constructed, minimizing the structural weight and maximizing the modal separation interval under dynamic stiffness and excitation frequency constraints. Numerical simulations, FE analysis, and prototype tests validate the method: the maximum analytical error is only 3.1%. Compared with uniform support designs, the optimized structure achieves a 40% weight reduction, a 40% increase in minimum modal separation, and a 65% reduction in the RMS tracking error. This work provides an efficient, deterministic dynamic design method for large-diameter ring structures, transforming vibration control from empirical adjustment into a precise, physics-informed optimization. Full article

Background/Objectives: This paper investigates the application of radial basis function (RBF) interpolation to adapt the Toyota Human Model for Safety (THUMS) version 6 finite element (FE) models to diverse anthropometric profiles using ANSUR II data. The research focuses on generating personalized human body models (HBMs) across 50th, 80th, and 98th percentiles for both sexes in standing and seated postures, evaluating mesh quality with quantitative metrics, and assessing posture-dependent transformations. Methods: The geometric accuracy for the standing configuration was quantified using DICE similarity coefficients and the 95th percentile Hausdorff distance (HD95). Results: While global whole-body DICE similarity averaged approximately 0.40 due to an inherent variability in distal limb positioning, regional analysis demonstrated strong volumetric overlap in the critical chest and torso regions with DICE values ranging from 0.80 to 0.88. Regional HD95 values were within 20–30 mm across most of the surface area. Surfaces distance analyses showed that more than 95% of the nodes were within $\pm 20$ mm of the target surfaces with the distribution centered near zero across all the percentiles. The mesh quality for both standing and seated morphs demonstrated low violation rates with the aspect ratio being 28% to 30%, while warpage, skewness and, Jacobian determinants were less than 15%. The seated morphs preserved anatomical alignment and posture despite mesh density differences between the postures. Conclusions: These findings indicate that the morphing process preserves anatomical fidelity while highlighting the need for further optimization to mitigate localized distortions in dynamic simulations. Full article

This study investigates the fracture initiation and propagation mechanisms of continuously reinforced concrete–asphalt (CRC+AC) composite pavements under the synergistic effects of diurnal temperature fluctuations and non-uniform tire loading. A three-dimensional (3D) thermo-mechanical coupled finite element (FE) model was developed, with its underlying mechanical framework validated through laboratory-scale model tests conducted at 20 °C. The experimental results, involving strain monitoring at varying depths, demonstrated a high degree of consistency with numerical predictions in terms of spatial strain distribution, thereby ensuring the model’s reliability in capturing interlayer load-transfer efficiency. Building upon this validated mechanical foundation, numerical simulations were extended to analyze the low-temperature fracture response. The numerical results indicate that the maximum longitudinal and transverse tensile stresses in the asphalt layer are concentrated at the pavement surface, whereas the maximum shear stress occurs at a depth of 2–3 cm near the leading and trailing edges of the wheel load. Under low-temperature gradients, the Mode I stress intensity factor (K_I) at the crack tip exhibits a distinct diurnal opening–closing–reopening pattern, peaking at approximately 220 kPa·m^1/2 during the early morning hours (05:00–06:00). Furthermore, numerical simulations reveal the significant sensitivity of shear-sliding to axle loads; specifically, the peak Mode II stress intensity factor (K_II) increases monotonically from 190 to 230 kPa·m^1/2 as the axle load rises from 10 t to 16 t. Under non-uniform contact pressure, longitudinal cracking is primarily characterized by a mixed Mode I and Mode II mechanism driven by coupled tensile and shear stresses, whereas transverse cracking is dominated by Mode II shear failure. These findings suggest that implementing targeted traffic restrictions for overloaded vehicles during identified high-risk time windows can significantly enhance the structural durability and service life of composite pavements in cold regions. Full article

This study presents a comprehensive numerical investigation into the combined bending–shear behaviour of hollow-flanged cold-formed steel (HFCFS) beams filled with lightweight concrete (LWC). Although previous research has independently examined the pure bending and pure shear responses of these composite members, their structural performance under simultaneous bending and shear remains unexplored. In this work, advanced three-dimensional finite element (FE) models were developed in ABAQUS to simulate the nonlinear behaviour of LWC-filled HFCFS beams subjected to various shear-span ratios. The modelling approach was validated using published experimental data and extended through a systematic parametric study that considered three beam geometries, two steel yield strengths (350 MPa and 450 MPa), two lightweight-concrete strengths (30 MPa and 50 MPa), and aspect ratios ranging from 1.5 to 3.5. The results demonstrated a clear progression of governing failure modes, from web shear buckling at low aspect ratios to combined shear–flexure interaction at intermediate spans and flexural-dominated failure at larger spans. Normalised shear and bending demand–capacity ratios (V/Vu and M/Mu) were used to identify the dominant limit state, revealing a predictable transition from shear-controlled to flexure-controlled behaviour. The findings enhance the understanding of composite thin-walled steel–concrete systems under combined actions and highlight the need for dedicated design rules for CF-HFCFS beams operating within the bending–shear interaction domain. Full article

This study presents an analytical and numerical framework to describe the debonding behavior of fiber-reinforced cementitious matrix (FRCM)-reinforced flat masonry elements under direct shear tests. A sawtooth shear stress–slip law, initially proposed for Steel Reinforced Grout (SRG) systems by two of the authors, is calibrated for a PBO-FRCM system based on the experimental results available in the literature. These recent experimental outcomes on flat masonry pillars serve to validate the model by capturing essential interface behaviors, including residual strength and pseudo-linear hardening. Furthermore, a finite element (FE) model of the specimens has been developed to simulate the interface response, allowing for a comparison between numerical predictions and experimental results. The sawtooth law is implemented directly in commercial FE software without the need for custom coding. Additionally, a mesh sensitivity analysis was performed to verify numerical stability and identify the optimal discretization parameters for consistent model response. Results show good agreement among experimental observations, the sawtooth analytical model, and FE simulations. The analytical model slightly underestimates the experimental peak load by about 4–6%, while the FE predictions differ from the experimental results by less than 10%, confirming the reliability of the proposed modeling framework. Full article

This study investigates the shear performance of reinforced concrete (RC) beams strengthened with near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) ropes under ambient and elevated temperature conditions. An experimental program comprising twelve RC beams was conducted, including both normal- and high-strength concrete specimens. The beams were strengthened using CFRP ropes installed at two orientations (45° and 90°) and two spacing configurations (150 mm and 200 mm). Ten specimens were exposed to a temperature of 600 °C prior to shear testing. The experimental results were evaluated against finite element (FE) simulations and shear strength predictions obtained from ACI 440.2R provisions. The FE models demonstrated close agreement with the observed experimental response, whereas ACI 440.2R consistently yielded conservative shear strength estimates, particularly for high-strength concrete beams. The results confirm that inclined CFRP configurations and reduced rope spacing significantly enhance shear capacity, even after severe thermal exposure, with measured strength gains reaching approximately 75% relative to unheated control beams and up to 135% compared to heated control specimen. The findings emphasize the sensitivity of NSM CFRP in terms of strengthening effectiveness to elevated temperature and highlight the limitations of existing design provisions when applied to fire-damaged RC members. Full article

During circumferential tensioning of prestressing strands in U-shaped aqueducts, longitudinal tensile stresses may develop and impair crack resistance. Most existing studies rely on three-dimensional finite element (FE) simulations. Although accurate, FE modeling is time-consuming and unsuitable for rapid scheme evaluation during construction. To overcome this limitation, the U-shaped aqueduct was first simplified as a cylindrical shell and the feasibility of this idealization was verified. An approximate analytical solution was then derived from cylindrical shell theory to predict the longitudinal stress induced by circumferential prestressing. Practical factors, including non-uniform wall thickness, non-equidistant strand spacing, and strand positional deviations, were incorporated to improve engineering applicability. FE results confirm good agreement, with RMSE of 0.055–0.169 MPa and NRMSE of 2.3–19.6%, where the upper bound occurs only in localized regions. The method was further applied to an engineering project to optimize the tensioning scheme. With a rational interval-tensioning procedure, the peak longitudinal tensile stress was reduced by 31.6%. Overall, the proposed approach enables rapid stress estimation and supports preliminary screening and optimization of circumferential tensioning schemes. Full article

This study presents a newly conducted comprehensive investigation into the lateral torsional buckling (LTB) behavior of un-bonded pre-stressed (PS) thin-walled steel I-beams subjected to non-uniform bending moments, combining a numerical study with a machine learning (ML) approach and experimental validation. Despite extensive prior work, no exact analytical solution exists particularly for non-uniform bending or can be extremely complicated, as the resulting differential equations contain variable coefficients particularly under non-uniform bending due to the complexity of the PS system. To overcome this limitation, a numerical study using finite element (FE) analysis is first conducted with emphasis on the key geometric and pre-stressing parameters, including unbraced beam length, tendon eccentricity, deviators configurations, and pre-stressing force, to evaluate the LTB behavior. The FE modeling was then validated against experimental testing to ensure the accuracy and reliability of the FE solutions. Subsequently, a comprehensive dataset is generated using FE simulations to train the ML models aimed at predicting the LTB resistance of the PS system. This study presents three ML approaches, including support vector regression (SVR), random forest (RF) and least-square boosting (LSBoost), and their optimal hyperparameters are determined using Bayesian optimization (BO) to enhance the prediction performance. The results indicate that the LTB capacity predicted by the Bayesian-optimized ML models achieve high predictive accuracy and are in close agreement with numerical FE simulations, thereby highlighting their potential in capturing the complex, underlying non-linear interactions influencing the buckling behavior of the PS structural system. Accordingly, the proposed framework offers a robust and effective predictive tool for evaluating LTB resistance, particularly under non-uniform bending where exact analytical solutions are not available, and for supporting the design and assessment of PS steel structures. Full article

This study presents an improved methodology for assessing the environmental sensitivity of the host rock in Huashan art paintings. A hygroscopic experiment was first designed to determine the moisture diffusion coefficient of the rock mass preserving the Huashan rock paintings, as verified by hygroscopic kinetics. Additionally, variations in color difference values were simultaneously used to quantitatively evaluate moisture absorption characteristics. Subsequently, a finite element (FE) simulation was conducted to assess potential damage to the rock art system with respect to varying environmental conditions. Regarding the correlated functions with consideration of the influencing factors, the environmental sensitivity of the host rock in Huashan art paintings was clarified to illustrate the deterioration process resulting from the combined effects of temperature and humidity. It is found that the deformation gradient (F) and maximum tensile stress (σ_max) exhibit a linear relationship with ambient temperature (T_a), and an exponential relationship with heat transfer coefficient (h). The ambient humidity (H_en) and surface humidity exchange coefficient (f) primarily influence the water content of the rock mass. This insight into the host rock in Huashan art paintings provides a valuable approach to highlight the active role of environmental conditions and offers an additional methodology to understand the detachment of large superficial rock flakes and the granular disintegration of the rock. Full article

Rod-end spherical bearings are widely used in heavy machinery, wind power, and transportation. Their bolted connections directly determine structural safety but are prone to pull-out failure under maximum articulation angle and heavy load. This study employs finite element (FE) simulation to elucidate the failure mechanism and, combined with Timoshenko beam theory, systematically analyses the effects of end cap parameters (size, height, modulus) on bolt head lateral force and bending moment. Results show that two-piece end caps induce abnormal contact and severe stress concentration under combined lateral and axial loads. A spigot design with optimised bolt number and contact geometry is proposed, reducing the additional bending moment from $1.882\times {10}^4$ N·mm to $2.193\times {10}^3$ N·mm and lateral load from $8.236\times {10}^5$ N to $7.092\times {10}^4$ N (over 88% reduction), bringing stress within a safe range. Although the numerical analysis was not directly verified experimentally, the experimental confirmation of the design’s functionality supports the optimisation. This study clarifies the pull-out mechanism and provides insight for anti-pull-out connections under high lateral forces. Full article