Search Results (1,038)

This research presents a physics-informed deep learning framework for investigating the magnetohydrodynamic flow of a dissipative non-Newtonian micropolar nanofluid induced by a stretching sheet, incorporating Stefan blowing, internal heat generation, and the zero nanoparticle mass flux condition. The physical model consists of the interplay between the microrotation dynamics, resistance of porosity on the microrotation, Brownian diffusion, and thermophoretic transport phenomenon. The numerical solutions for the nonlinear yielded equations that result from the above interaction are obtained by employing a PINN that considers the laws of physics and boundary conditions. With this technique, the flow behavior, temperature, concentration, and microrotation fields can be predicted accurately without requiring huge datasets. This shows the ability of PINNs to numerically treat highly-coupled nonlinear transport equations in a very efficient manner compared to other traditional methods. The important discoveries from this study include that the porous and magnetic factors increased the skin friction coefficient, but the magnetic effect and viscous dissipation decreased the rate of heat transfer, and the thermophoresis effect decreased the rate of mass transfer while the Brownian effect increased it. The precision of the PINN algorithm is confirmed by comparison of the results with the earlier findings, which proves very high accuracy and hence the robustness of the current computing framework. Results of this research are useful for the development of some thermal management systems, energy converters, cooling methods, chemical reaction processes, fuel cell technology, porous media reactors, and ocean engineering involving the transport of complicated non-Newtonian nanofluids. Full article

The elastoplastic behaviour and failure of unreinforced masonry structures under biaxial loading are critically governed by the mechanical response of brick–mortar contact interfaces. Detailed finite element micromodelling explicitly resolves these elements, offering rigorous numerical representation; however, practical implementation requires the determination of contact stiffness parameters, for which no established experimentally calibrated expressions exist. This study presents an experimental-numerical calibration methodology integrating experimental characterisation of constituent materials and small-scale masonry specimens with numerical validation, using a concrete damaged plasticity model for quasi-brittle materials and traction-separation laws for interfaces, applied to a specific ceramic masonry system. The proposed methodology provides a practical and reproducible basis for experimental calibration of the contact stiffness parameters required in the detailed micromodelling of brick–mortar interfaces. Numerical simulations reproduce experimental behaviour, with peak load predictions within ±6% for normal and ±1% for shear loading. Detailed micromodelling reveals that normal stresses develop at interfaces even under nominally pure shear, evidencing coupled normal-tangential behaviour, the key role of normal adhesive contact strength, and the justification for the cohesive–frictional interface characterisation. Full article

During the radial braiding process, spindle motion induces periodic load excitations as they move with the turntable. Based on the kinematics analysis of the spindles, this study derives a tension-load torque mapping model and establishes a multi-degree-of-freedom (MDOF) nonlinear dynamic model that incorporates dynamic torque and gear tooth friction. The system’s governing differential equations are solved numerically using the fourth-order Runge–Kutta method to obtain steady-state responses under various combinations of tension and rotational speed. Results indicate that increasing yarn tension reduces the stability margin of the system’s phase trajectories, and the basin of attraction area for periodic motion decreases approximately linearly as the tension increases. Furthermore, friction exhibits dual characteristics across different frequency regimes: at operating frequencies below 1.05, friction acts as a damping mechanism to maintain system stability; however, beyond this threshold, the friction reversal mechanism triggers chaotic behavior. Full article

Conventional roadheader cutting tools are subjected to substantial forces, intense impacts, and friction during rock excavation, resulting in excessive energy consumption and accelerated tool wear. To address these challenges, undercutting technology has emerged as a promising alternative for integrating disc cutters into roadheaders. In this study, a comprehensive mechanical investigation is conducted on an Oscillating Disc Cutter (ODC) based on the undercutting principle to enhance fragmentation efficiency and minimize energy requirements. A high-fidelity numerical framework, coupling the Finite Element Method (FEM) and Smoothed Particle Hydrodynamics (SPH), is established to simulate the dynamic ODC cutting process. This model is rigorously validated against both theoretical analyses and experimental data. Results demonstrate that the ODC can reduce the minimum specific energy by 78% compared to conventional non-eccentric cutters and attenuates the average rolling, side, and normal forces by 70.9%, 59.4%, and 67.9%, respectively. Furthermore, parametric analysis reveals a strong sensitivity of cutting performance to oscillation frequency and feed rate. These findings confirm that the ODC mechanism effectively mitigates cutting resistance and optimizes rock fragmentation, providing essential theoretical and practical guidance for the development of high-efficiency underground excavation equipment. Full article

A unified transient deterministic lubrication model is developed for the analysis of rough, starved, and coated contacts within a single, fully-coupled numerical framework capable of resolving boundary, mixed, and full-film lubrication regimes. The model is formulated with the finite volume method on a curvilinear grid and extends conventional full-film formulations through the introduction of a semi-system methodology, enabling robust treatment of complex multi-regime conditions. A key distinguishing feature of the framework is the direct resolution of thermal effects within both the lubricant and solid domains through solution of the energy equation. Unlike many existing mixed lubrication models that rely on analytical temperature approximations, the present approach captures transient, asperity-scale temperature evolution explicitly, allowing accurate representation of local thermo-mechanical interactions. Two case studies are presented to demonstrate the capabilities of the model. The first examines transient starvation in rough contacts with isotropic sinusoidal topographies of varying wavelength, as well as random machined surfaces, revealing a strong dependence of lubricant entrainment, asperity interaction, and localised heating on surface morphology. The second study investigates the role of coating thermal properties under transient starved conditions, demonstrating strong coupling between heat transport, viscosity variations, and frictional response. Overall, the proposed framework provides a robust and physically consistent platform for the simulation of transient lubrication phenomena under realistic operating conditions, enabling detailed insight into roughness, starvation, and thermal effects across regimes using a fully-coupled approach. Full article

The accessory gearbox of an aero-engine operates under high-speed and heavy-load conditions, where insufficient lubrication may lead to oil-film failure, increased frictional losses, and reduced transmission reliability. Therefore, understanding oil-jet injection and tooth surface oil-film spreading characteristics is essential for improving lubrication performance. In this study, a three-dimensional geometric model incorporating the meshing region and oil nozzles was established based on a typical accessory gear pair. The model employs the VOF multiphase flow approach and the standard k-ε turbulence model, coupled with dynamic mesh techniques to accurately capture the transient interactions between gear rotation and oil–air two-phase flow. Numerical simulations reveal the dynamic evolution of oil injection, impingement on the tooth surface, oil-film spreading, and transport into the meshing zone, while the effects of injection velocity and nozzle length on lubrication performance are quantitatively analyzed. Results indicate that an injection velocity of 45–55 m/s yields optimal oil-film coverage and uniformity, and a nozzle length of h = 30 mm minimizes jet energy decay and airflow interference, achieving uniform oil filling in the meshing zone. The optimal lubrication performance for accessory gears is obtained at an injection velocity of 45–55 m/s and a nozzle length of 30 mm. This study provides a reference for the design optimization of accessory gear lubrication systems. Full article

To improve the accuracy of discrete element method (DEM) simulation parameters for American ginseng precision seeding and to overcome the reliance of metering device design on empirical trial-and-error—a consequence of the scarcity of physical property data for specialised medicinal seeds and the low transferability of generic parameters—this study focuses on germination-induced American ginseng seeds from the Jilin Baishan production region. Intrinsic parameters, including triaxial dimensions, density, elastic modulus, and Poisson’s ratio, were determined through physical experiments. The free-fall collision method, inclined plane sliding method, and rolling method were employed to measure the contact parameters between seeds and the ABS plastic material. Based on the measured results, a Plackett–Burman design was used to screen for three inter-particle contact parameters that significantly affect the angle of repose (AOR), and the steepest ascent test was subsequently applied to determine their optimal value intervals. A Box–Behnken design was further adopted to construct a second-order regression model and perform parameter optimisation. The calibrated seed–seed static friction coefficient was 0.759, the seed–seed rolling friction coefficient was 0.089, and the seed–seed coefficient of restitution was 0.17. The simulated static and dynamic AORs deviated from the physical test values by only 0.33% and 0.67%, respectively. In the bench validation using a pneumatic scoop-type seed metering device, a DEM–CFD coupling model was established to simulate the seeding process; the relative errors of the multiple rate and missing rate between simulation and bench tests were both below 8%, meeting the requirements of the relevant national standards. The calibrated parameters showed acceptable reliability under the tested conditions and can provide a theoretical basis for the selection of working parameters and the design optimisation of American ginseng precision seed metering devices. Full article

Tribological systems involving rolling and sliding contacts generate coupled mechanical interactions that govern friction, wear, and surface degradation. These interactions produce multiaxial residual stresses that influence crack initiation, accelerate wear, and promote environmentally assisted damage. In corrosive environments, tribo-corrosion further intensifies material degradation through the combined action of mechanical wear and electrochemical reactions. Protective organic and metallic coatings are widely used to mitigate these effects; however, their performance depends on adhesion, stress evolution, and resistance to coupled mechanical and chemical degradation. Among the principal failure mechanisms, cathodic blistering is strongly influenced by diffusion, interfacial stresses, and tribological loading. This review therefore links cathodic blister evolution with coating degradation under combined tribological and corrosive conditions. The review critically examines the Khan–Nazir meso-mechanics Models I, II, and III, which integrate stress-assisted diffusion, residual stress development, mixed-mode fracture, and coating–substrate delamination. Recent developments have extended these models through substrate deformation, multilayer coating architectures, and electro-chemo-mechanical phase-field simulations. The models demonstrate how diffusion-induced and residual stresses interact with tribological loading to initiate and propagate interfacial defects. The analysis shows that blister evolution is primarily governed by elastic modulus mismatch and friction-induced stress fields, while stability criteria predict non-axisymmetric blister morphologies associated with buckling and delamination. Overall, this review highlights the significance of the Khan–Nazir models for understanding wear, friction, and coating durability in engineering systems. The unified framework provides valuable guidance for the design and optimisation of advanced multilayer protective coatings for marine, automotive, energy, and manufacturing applications operating under rolling/sliding contact and tribo-corrosion environments. Full article

To investigate the influence of fin–wall subcooling regulation on moist-air condensation dehumidification, this study numerically investigates the dehumidification performance and energy response of a thermoelectric cooling system under three subcooling control strategies: gradient subcooling, frequency-modulated subcooling, and amplitude-modulated subcooling. Under strictly identical gas-phase parameters and geometric conditions, the moisture removal rate per unit area, the friction-mass-transfer factor, and the moisture-removal energy efficiency are adopted as evaluation indicators. The results show that gradient subcooling exerts a pronounced non-monotonic influence on dehumidification performance, with an optimal subcooling range around 32–33 K. Further increases in subcooling lead to reduced dehumidification performance accompanied by significantly increased energy-related indicators, indicating a transition toward a high-energy, low-benefit operating regime. Compared with gradient subcooling, frequency-modulated subcooling provides a more favorable balance between dehumidification performance and energy efficiency under relatively high subcooling conditions, demonstrating a clear frequency–subcooling coupling effect. In contrast, amplitude-modulated subcooling plays only a secondary role and shows limited influence on both dehumidification performance and energy-related indicators within the investigated parameter range. Full article

The hydroforming performance of trailing arms is governed by the coupled effects of feed parameters, pressure schedules and frictional characteristics. Improper parameter matching readily induces typical forming defects such as wrinkling, cracking and uneven wall thickness. To address this issue, a multi-objective optimization method for hydroforming is proposed in this study. Taking the maximum wall thickness, minimum wall thickness and die-to-workpiece gap of the tubular blank as optimization objectives, and the internal pressure and right-side axial feed velocity as design variables, an integrated numerical simulation framework combining the Archive-based Micro Genetic Algorithm (AMGA) and LS-DYNA is established to analyze the hydroforming process. By adaptively adjusting the key control points of internal pressure and axial feed loading curves, the developed method expands the solution space and realizes the automatic optimization of loading paths. The results reveal that the maximum wall thinning rate of the tubular component drops from 20.4% to 14.8%. Meanwhile, the wall thickness uniformity is improved and forming defects are effectively suppressed while the thickening rate remains stable. Furthermore, a complete round of optimization calculation involving thousands of finite element solutions can yield a complete set of Pareto non-dominated solutions. In this paper, the AMGA multi-objective optimization algorithm is adopted to acquire the optimal loading paths, and physical prototype experiments are carried out relying on self-developed 2000 T hydroforming equipment. Comparisons between measured and simulated wall thickness values of the tubular component show that the maximum relative error is controlled within 7.46%, which verifies the reliable engineering applicability of the proposed optimization scheme and provides new insight into the process optimization for forming similar structural components. Full article

To address the multi-objective optimization of stamping process parameters for vehicle components, a hybrid framework coupling Dynaform simulations, Orthogonal Experimental Design, BPNN, NSGA-II, and TOPSIS was proposed. Taking car door accessories as a case study, OED was utilized to investigate the interacting effects of blank holder force, friction coefficient, stamping speed, and die clearance on the maximum thinning and thickening rates. The simulated data trained a BPNN to construct the highly non-linear mapping relationships. Subsequently, the NSGA-II algorithm generated the Pareto optimal frontier, and TOPSIS objectively selected the best compromise process parameters: a blank holder force of 43,113 N, a friction coefficient of 0.13, a stamping speed of 2496 mm/s, and a die clearance of 1.0 mm. Applying this combination effectively constrained the maximum thinning and thickening rates to 41.4% and 16.8% respectively. The BPNN relative prediction errors against numerical validation were merely 0.0691% and 6.9930%, fully verifying the high fidelity and effectiveness of the proposed optimization methodology. Full article

Lightweight flapping-wing robots are affected by structural flexibility, wind disturbances, and static friction in basal passive joints during perching and attitude-holding tasks. These coupled effects can make conventional PID and sliding mode control (SMC) produce error amplification, torque fluctuation, flexible-response excitation, and attitude-boundary violation. This study establishes an ADAMS–Simulink co-simulation platform for a rigid–flexible coupled flapping-wing robot and proposes a diffeomorphism-based attitude-constrained controller. The inverse hyperbolic tangent mapping transforms bounded physical errors into unbounded virtual errors, allowing smooth small-error regulation and stronger constraint enforcement near safety boundaries. Wind-free tracking, compound wind rejection, pulse wind scanning, mapping-parameter sensitivity, and a CBF-QP safety-filtered baseline are evaluated. In manuscript parameter-synchronized ADAMS 2024 reruns under a 2 m/s steady wind with a 1 m/s pulse, PID and SMC show runaway angular excursions of 1602.56° and 381,330.03°, whereas the proposed method remains bounded at 23.58° with an RMSE of 2.943° and no boundary violation. The CBF-QP baseline still violates the boundary at 1394°. The results show improved tracking accuracy, boundary protection, measured-channel flexible-excitation attenuation, and stable disturbance recovery. Full article

This paper presents a method of using recycled tyre-derived grids (RTDG) as reinforcement materials for mechanical stabilised weathered sand embankment. To demonstrate the effectiveness of the RTDG-reinforced weathered sand on shear behaviour, large-scale triaxial tests were conducted under different confining pressures and reinforcement layers. The test results indicate: (1) RTDG reinforcement significantly alters the shear failure mode of weathered sand, transitioning it from shear failure to bulging failure. (2) RTDG reinforcement enhances the ultimate deviatoric stress of specimens by 20–30%, transforming the stress–strain response from strain softening to strain hardening. (3) RTDG reinforcement causes apparent cohesion to increase at an approximate linear rate of 37.2% per reinforcement layer, whereas the internal friction angle exhibits only a gradual increase. (4) The coupled effect of RTDG reinforcement and confining pressure alter volumetric behaviour from shear contraction–dilation patterns to solely shear contraction. It also reduces maximum dilation strain by about 50% and the dilation angle by 23%. (5) Two shear strength prediction models based on confinement enhancement (CEB) and interface friction (IFB) were proposed. Comparative analysis shows that, within the present dataset, the IFB model exhibits lower prediction error and a more stable error distribution than the CEB model, with a WRAI value of 0.033. Accordingly, the IFB model provides an effective prediction approach for estimating the shear strength of RTDG-reinforced weathered sand within the investigated test range, and the corresponding prediction results may serve as a preliminary reference for the engineering evaluation of RTDG-reinforced weathered sand. Full article

Die forging is a widely used production method for manufacturing high-strength components with high accuracy and good mechanical properties. Since the die forging process involves many complicated thermo-mechanical coupled field physical problems, such as large plastic deformation, high temperature, friction, and heat transfer, etc., experimental studies are difficult and expensive to perform. The numerical simulation method has become the main method of study and optimal design for the die forging process. This paper reviews the published papers on numerical simulation of the die forging process from 2016 to 2026, in a structured literature review of computational simulations dealing with die forging processes. The literature search was conducted using the Scopus and Web of Science databases. After screening and full-text assessment, 24 relevant journal articles were selected for this paper. The articles studied were analyzed in terms of finite element modelling strategies, constitutive and material models used, friction and thermal boundary conditions considered, and process parameters. Typical results obtained from the studies discussed in the paper include stress, strain, temperature, forging load, and metal flow. The current state-of-the-art research has evolved from simple metal-flow predictions to more complex thermo-mechanical models, and even optimization-based models. Most of the current studies are based on experimentally derived constitutive equations, as well as more complex friction and heat-transfer models. Furthermore, studies applying optimization methods (Taguchi methods, design of experiments, machine learning, artificial intelligence) are increasingly common. The growing interest in the digital twin concept and real-time process control is observed. However, experimental validation, thermal contact modelling, and simulation of stress, strain, temperature, and microstructure in one simulation remain key challenges. Full article

Friction stir welding (FSW) is an effective solid-state joining technique for magnesium alloys such as AZ31, owing to its ability to minimize conventional welding defects. Nevertheless, the process generates significant residual stresses that can impair the fatigue performance and dimensional stability of welded structures. In this study, a sequentially coupled thermo-mechanical finite element model was employed to characterize the residual stress distribution in FSW AZ31 Mg alloy. The calculated near-surface longitudinal residual stress was assessed against XRD measurements at five locations on the top surface, giving a root mean square error of about 10.34 MPa. The results revealed an M-shaped longitudinal residual stress profile with marked asymmetry between the advancing and retreating sides, associated with non-uniform heat input and the resulting asymmetric temperature history. Among the three stress components, the longitudinal residual stress was the largest, followed by the transverse component, while the normal stress was the smallest. The thermo-mechanically affected zone and the crown zone exhibited higher residual stresses compared to the heat-affected zone. In addition, the influences of welding speed and tool rotational speed on residual stress evolution were systematically evaluated. The longitudinal residual stress increased with welding speed up to 350 mm/min and subsequently decreased, while a peak value was observed at 1200 rpm. These numerical results provide useful guidance, within the studied parameter range, for welding-parameter selection and residual-stress control in magnesium alloy joints. Full article