Numerical Experimental Investigation Research Articles

The Numerical Simulation and Experimental Investigation of the Laser Quenching Process of GCr15 Joint Bearings

Joint bearings are widely used in modern industry in order to improve the mechanical properties of the outer surface of its inner ring. A laser quenching experiment was carried out in this paper. First of all, an experimental investigation was conducted on GCr15 ball-bearing material utilizing laser quenching, focusing on the effects of laser irradiation angles ranging from 0° to 10° and laser power levels between 600 W and 1100 W on the degree of hardening and microstructural alterations of the bearing material. Additionally, a reliable finite element analysis model was developed to assess the temperature field throughout the process. The findings indicate that an inclined laser enhances the stability of the hardened layer. Specifically, the hardening effect is minimal when the laser power is below 700 W, and optimal hardening is observed at power levels between 800 W and 900 W. During the laser quenching process when the temperature of the bearing material surpasses Ac1, the cooling rate can exceed 1700 °C/s. In regions where the peak temperature exceeds Ac1, the microstructure will undergo refinement, resulting in a reduction in the size of the martensite and a significant decrease in the number of carbides. In addition, the hardness value of these regions can be increased by 6 to 8 HRC, and the thickness of the quenching layer may exceed 0.3 mm. In the temperature range between Ac1 and Ms, the bearing material undergoes tempering, resulting in lower hardness compared to the base material, along with larger martensite and carbide particles. Furthermore, when using the overlap technique during the laser quenching, there will be a tempering zone both inside and on the surface of the bearing; meanwhile, the heat zones generated by different passes of the laser may have partly interacted, and the hardened zone generated by the previous pass may undergo tempering again.

Research on the infiltration law and enhancing application of dust suppressants in powder materials

ABSTRACT Dust emissions from open-pit mining pose a significant threat to environmental safety and human health. Currently, the range of dust suppressants used in coal mining is limited, often failing to account for their suitability across various stockpiles. This oversight results in poor infiltration after application, leading to insufficient crust formation and reduced durability. To explore the permeability of dust suppressant solutions in different stockpiles and develop a broader range of suppressants, numerical simulations were conducted to analyze the effects of liquid properties on infiltration rates. The results showed that increased liquid surface tension promotes infiltration, whereas higher solid-liquid contact angles and liquid viscosity inhibit it. Building on these findings, experimental work was undertaken using a water-based polyurethane with strong adhesion and low viscosity, combined with xanthan gum and polyethylene glycol, to optimize the dust suppressant formulation. The optimal binder formulation was found to contain 1.5% water-based polyurethane, 0.2% xanthan gum, and 1% polyethylene glycol. Infiltration experiments revealed distinct infiltration patterns for the dust suppressant solution in both rock and coal dust. The appropriate dosage of surfactants was also determined. The study indicated that surfactants enhance wettability and significantly reduce the solution’s surface tension. For hydrophilic rock dust, moderate surfactant addition improves permeability, while excessive amounts disrupt capillary forces. In contrast, for hydrophobic coal dust, wettability governs infiltration, with surfactants enhancing this property. Based on these findings, dust suppressant solutions suitable for both rock and coal dust were formulated. The formulations demonstrated excellent permeability, consolidation effects, and water resistance, as validated by tests measuring wind erosion resistance, crust strength, and water erosion resistance. The significance of this research lies in its comprehensive exploration of dust suppressant efficacy within different particulate media and the factors influencing penetration performance, providing important guidance for industrial and environmental management. With the rapid pace of industrialization, dust generation poses a serious threat to both the environment and human health, making the development of effective dust suppressants increasingly critical. This study employs numerical simulations and experimental investigations to reveal the impact of various solution properties on penetration performance, particularly highlighting the application of a novel aqueous polyurethane binder, which demonstrates strong adhesive properties and low viscosity. Through optimization of the binder composition via orthogonal experiments, the research identifies optimal surfactant concentrations tailored for rock and coal dust, thereby enhancing the penetration and binding capabilities of the suppressants. This finding not only improves the performance of dust suppressants but also provides a scientific basis for practical applications, effectively reducing dust dispersion, improving air quality, and protecting the ecological environment. Furthermore, the study validates the effectiveness and durability of the developed suppressants through wind erosion resistance, crust strength testing, and water erosion experiments. This research offers practical solutions for the mining, construction, and related industries in controlling dust, while also providing reliable scientific support for policymakers in environmental protection. In summary, this study not only holds significant academic value but also offers actionable guidance for dust control and environmental conservation in real-world applications.

Detecting and clustering structural damages using modal information and variational autoencoder with triple loss

Among vibration-based structural health monitoring (SHM), methods based on modal analysis are the most popular and efficient ones for assessing the inherent states of structures. The primary techniques involve tracking changes in modal parameters regularly during the monitoring period. Numerous studies have utilized both modal frequencies and mode shapes for damage detection, as mode shapes help identify damage locations, and the combination is more robust against environmental effects. Obviously, recent advances in machine learning (ML) and artificial intelligence (AI) have revolutionized SHM based on modal analysis. This study aims to develop a clustering technique using variational autoencoder (VAE) for classifying structural damages. To fully expand the entangled spaces that may arise from lower-dimensional representation, the loss function incorporates triplet loss (known as triplet VAE or tVAE) while preserving all dimensions in the encoded space. The proposed approach is thoroughly developed and evaluated using both numerical simulations and experimental investigations of multistory building structures. The effectiveness of detecting changes via VAE-based and tVAE-based modal clustering has been demonstrated under the consideration of environmental variations and uncertainties. Additionally, a procedure is suggested for the field applications and the proposed approach’s capability for structural inspection during long-term monitoring is showcased using a practical scenario.

Numerical simulation and experimental investigation of novel developed medium-pressure plasma polishing process of fused silica

Numerical simulation and experimental investigation of novel developed medium-pressure plasma polishing process of fused silica

Numerical simulation and experimental investigation of pressure riveting connection using the smoothed particle Galerkin method

Numerical simulation and experimental investigation of pressure riveting connection using the smoothed particle Galerkin method

Numerical simulation and experimental investigation of the propagation law of plasma pulse shock waves

Abstract Plasma pulse shock wave rock-breaking technology represents a novel approach to rock fracturing. Present research on this subject largely addresses rocks and electrodes, yet often neglects the critical influence of shock waves in the rock-breaking process. Therefore, it is necessary to further study the propagation law of the shock wave and its reflection and transmission. This paper undertakes experimental simulations using the RHT rock model to explore the propagation process of plasma pulse shock waves based on two variables: the medium and the shape of the electrode. Integrated with one-dimensional stress wave theory, the study examines the impact of four specific parameters—dielectric thickness, surrounding rock height, surrounding rock density, and surrounding rock porosity—on the reflection and transmission rates of shock waves. Pressure data collected from experimental platform are utilized to validate the study’s conclusions. The findings indicate that the propagation behaviors of shock waves differ significantly between water and air mediums. The shape of the electrode causes significant differences in the pressure exerted by the shock wave at the same location. Both the thickness of the dielectric and the porosity of the surrounding rock show a positive correlation with the reflection coefficient and a negative correlation with the transmission coefficient, while the density of the surrounding rock exhibits an inverse relationship. The height of the surrounding rock is irrelevant to both reflection and transmission coefficients.

Development of Piezoelectric Inertial Rotary Motor for Free-Space Optical Communication Systems.

This paper presents the design, development, and investigation of a novel piezoelectric inertial motor whose target application is the low Earth orbit (LEO) temperature conditions. The motor utilizes the inertial stick-slip principle, driven by the first bending mode of three piezoelectric bimorph plates, and is compact and lightweight, with a total volume of 443 cm3 and a mass of 28.14 g. Numerical simulations and experimental investigations were conducted to assess the mechanical and electromechanical performance of the motor in a temperature range from -20 °C to 40 °C. The results show that the motor's resonant frequency decreases from 12,810 Hz at -20 °C to 12,640 Hz at 40 °C, with a total deviation of 170 Hz. The displacement amplitude increased from 12.61 μm to 13.31 μm across the same temperature range, indicating an improved mechanical response at higher temperatures. The motor achieved a maximum angular speed up to 1200 RPM and a stall torque of 13.1 N·mm at an excitation voltage amplitude of 180 Vp-p. The simple and scalable design, combined with its stability under varying temperature conditions, makes it well suited for small satellite applications, particularly in precision positioning tasks such as satellite orientation and free-space optical (FSO) communications.

Dual Role of TRPV1 Channels in Cerebral Stroke: An Exploration from a Mechanistic and Therapeutic Perspective.

Transient receptor potential vanilloid subfamily member 1 (TRPV1) has been strongly implicated in the pathophysiology of cerebral stroke. However, the exact role and mechanism remain elusive. TPRV1 channels are exclusively present in the neurovascular system and involve many neuronal processes. Numerous experimental investigations have demonstrated that TRPV1 channel blockers or the lack of TRPV1 channels may prevent harmful inflammatory responses during ischemia-reperfusion injury, hence conferring neuroprotection. However, TRPV1 agonists such as capsaicin and some other non-specific TRPV1 activators may induce transient/slight degree of TRPV1 channel activation to confer neuroprotection through a variety of mechanisms, including hypothermia induction, improving vascular functions, inducing autophagy, preventing neuronal death, improving memory deficits, and inhibiting inflammation. Another factor in capsaicin-mediated neuroprotection could be the desensitization of TRPV1 channels. Based on the summarized evidence, it may be plausible to suggest that TPRV1 channels have a dual role in ischemia-reperfusion-induced cerebral injury, and thus, both agonists and antagonists may produce neuroprotection depending upon the dose and duration. The current review summarizes the dual function of TRPV1 in ischemia-reperfusion-induced cerebral injury models, explains its mechanism, and predicts the future.

Numerical Simulation and Experimental Investigation on Friction and Lubrication Behaviors of Chevron Micro-Textured Valve Plate/Cylinder Block Interface With Various Area Densities

Abstract As the critical friction pairs of swashplate-type axial piston pumps, the cylinder block/valve plate lubricating interface is the primary source of friction, wear, and leakage in axial piston pumps. Surface micro-texturing has been widely employed in cylinder block/valve plate conjunctions to ameliorate tribological performance. However, little research has been conducted to investigate the influence of chevron micro-texture area density on the tribological behaviors and lubricating properties of cylinder block/valve plate interface both experimentally and numerically. In this article, the chevron micro-textures with various area densities were manufactured on H62 brass by micro-milling and subsequently characterized with a laser scanning confocal microscope (LSCM). The friction and wear performance of H62 brass/38CrMoAl conjunctions were obtained via disc-on-disc tribological tests to simulate the cylinder block/valve plate lubricating interface. Moreover, the load-carrying capacity of untextured and chevron micro-textured samples was numerically investigated under hydrodynamic lubrication. It was found that the chevron micro-textured surface with an area density of 30.1% displayed the lowest friction coefficient and the shallowest wear depth. Although the load-carrying capacity of chevron micro-textured samples with a high dimple area density was larger, the severe stress concentration induced by the reduced micro-texture spacing caused the increment and large fluctuations of friction coefficient.

Numerical simulation and experimental investigation on the thermal-fluid-solid multi-physical field coupling characteristics of wet friction pairs considering cavitation effect

The coupling characteristics of thermal-fluid-solid multi-physical fields are crucial in determining the operational performance and service life of wet clutches. However, the underlying mechanism behind the influence of cavitation effect on these coupling characteristics remains unclear. Therefore, we propose a numerical solution method for considering cavitation effect in the coupling characteristics based on the multi-physical field coupling platform MPCCI combined with ABAQUS and FLUENT. The distribution patterns and intercoupling relationships among temperature field, flow field, and stress-strain field are comprehensively analyze. The influence of relative speed, cross-sectional shape of oil grooves, and oil flow on the coupling characteristics is investigated. Experimental validation confirms that the proposed model accurately predicts temperature variation by accounting for cavitation effect. The temperature distribution of steel discs is notably affected by the cavitation effect, leading to an elevation in the maximum temperature and uneven distribution characterized by localized hot spots along the circumferential direction. Accounting for the cavitation effect reduces errors between calculated and experimental values of temperature rise. The convective heat transfer coefficient gradually decreases radially, with a more pronounced decrease in the cavitation region. An increase in relative speed and a decrease in oil flow both lead to greater cavitation volume, resulting in higher temperature of steel discs. Among three different cross-sectional shapes of oil grooves investigated, rectangular grooves exhibit larger areas affected by cavitation compared to triangular grooves. These research findings provide a theoretical basis and technical support for accurate prediction of thermal characteristics within high-power wet clutches.

Thermo-hydrodynamic performance and geyser boiling flows of a novel co-axial condensing heat pipe (CCHP) for low-grade green energy exploitations

Due to their excellent heat transfer efficiency, two-phase closed thermosiphons (TPCTs) are essential for solar applications and the cooling of electronics. In this research, a novel coaxial condensing heat pipe (CCHP) was proposed, which has a more compact structure compared to traditional heat pipe, given the same volume and heat transfer area. Numerical modeling and experimental investigation were fully utilized to examine the influences of heat inputs, inclination angles, liquid filling ratios, and working mediums on the heat transmission properties of CCHP. The vapor-liquid flow phenomenon along with the thermal and mass transmission mechanism of CCHP under various operating conditions were explored. Our findings demonstrated that CCHP exhibited optimal thermal transmission performance at the tilt angle of 60° when the filling rate is 50 % and the input power is 100 W, the minimum thermal resistance of CCHP is 0.284K/W. At the tilt angle of 60° and input power of 100 W, CCHP has the lowest thermal resistance of 0.267K/W. Besides, the utilization of ethanol as a working medium could simultaneously reduce the evaporator temperature and enhance the thermal properties of CCHP. Inside CCHP, "geyser boiling" phenomena was further observed. Our experimental findings and numerical ones agreed well for each other. This innovative heat pipe could be confident and robust applied in the solar energy collection and relevant heat transfer enhancement fields.

Rotationally Induced Local Heat Transfer Features in a Two-Pass Cooling Channel: Experimental–Numerical Investigation

Turbine blades for modern turbomachinery applications often exhibit complex twisted designs that aim to reduce aerodynamic losses, thereby improving the overall machine performance. This results in intricate internal cooling configurations that change their spanwise orientation with respect to the rotational axis. In the present study, the local heat transfer in a generic two-pass turbine cooling channel is investigated under engine-similar rotating conditions (Ro={0…0.50}) through the transient Thermochromic Liquid Crystal (TLC) measurement technique. Three different angles of attack (α={−18.5°;+8°;+46.5°}) are investigated to emulate the heat transfer characteristics in an internal cooling channel of a real turbine blade application at different spanwise positions. A numerical approach based on steady-state Reynolds-averaged Navier–Stokes (RANS) simulations in ANSYS CFX is validated against the experimental method, showing generally good agreement and, thus, qualifying for future heat transfer predictions. Experimental and numerical data clearly demonstrate the substantial impact of the angle of attack on the local heat transfer structure, especially for the radially outward flow of the first passage, owing to the particular Coriolis force direction at each angle of attack. Furthermore, results underscore the strong influence of the rotational speed on the overall heat transfer level, with an enhancement effect for the radially outward flow (first passage) and a reduction effect for the radially inward flow (second passage).

Numerical approach and experimental investigation of a stratified hot water storage tank for domestic hot water production

Thermal stratification within storage tanks plays a critical role in the efficiency of thermal energy storage systems. In this paper, one-dimensional numerical model of a stratified storage tank is developed to simulate the thermal stratification process within a storage tank during the charging and the discharging processes, capturing the temperature distribution inside the storage tank over time. This work investigates the evolution and transient behavior of stratified flows during the heating and cooling process within sensible-heat energy storage systems under ReD=167 and ReD=616 for heating process. For that purpose, an experimental campaign was performed in an instrumented water storage tank to measure the stratification process when a hot water round jet was injected into a slender cylindrical tank filled with an initially uniform hydrostatic water field stabilized at a lower temperature. This information was used to develop a simple 1D model able to be applied during long-term charging/discharging transients of these kind of systems. The 1D model developed was validated against the experiments performed following prototypical charging/discharging tests according to the standard EN16147 and can be used to describe the energy performance of this kind of systems during long-term charging/discharging sequences. The present model provides a reduction of about 5 % of the error of the time of the water cooling process with respect to other models in the literature.

Modeling of a metal hydride energy storage tank dynamics using hybrid numerical, experimental, and machine learning methods

This study presents an integrated analysis combining numerical simulations, experimental investigations, and machine learning models to simulate the performance of metal hydride systems for hydrogen storage under various conditions by using a LaNi5 metal hydride cylindrical tank of 500 NL capacity, with a focus on PCM thermal enhancements and surface water heating and cooling. Numerical simulations offer insights into thermal and reaction dynamics, while experimental data are used for model validation and supplemented with additional numerical data for training a FFNN model to predict dynamic hydrogen flow, surface temperature, and surface heat flux. The obtained mean RMSEs for charging/discharging experimental data is 2.8 SOC% for the state of charge and 0.3 °C for surface temperatures. The study compares the effectiveness of water cooling and heating in metal hydride surface across different temperatures, highlighting their impact on the efficiency of hydrogen absorption and desorption processes. Energy consumption is shown to be non-linear; during charging, heat flux peaks before decreases rapidly within around 0.2 h. During discharging, heat flux rises steadily. The study also explores the impact of adding copper fins to the PCM covering metal hydride system, revealing significant improvements in charging and discharging efficiency, specifically, the integration of 16 copper fins led to a notable decrease in complete charging time from approximately 6.5 h to just over 5.2 h, and in complete discharging time from around 4.5 h to under 3.96 h. Using PCM, the highest heat flux is 5 times less during charge and 2 times less during discharge than that for water cooling mode.

Experimental–numerical investigation of aerodynamics effects produced by the rear wing mainplane deformation in a formula 1 racing vehicle

Experimental–numerical investigation of aerodynamics effects produced by the rear wing mainplane deformation in a formula 1 racing vehicle

Thermal performance augmentation of microchannel using curved rectangular winglet vortex generators having rectangular perforation

This article innovatively introduces the application of punched curved rectangular wing vortex generators positioned on opposing sides of a rectangular microchannel. Through a comprehensive approach combining numerical simulations and experimental investigations, the flow dynamics and heat transfer performance of these VGs under turbulent conditions are thoroughly examined. This analysis is performed in the turbulent flow regime, specifically at Reynolds number ranging from 2500 to 3500. The governing equations are solved by using SST k-ω model. To evaluate the behavior of mixed vortices, a range of key metrics is utilized, including the Nusselt number ratio, friction coefficient ratio, and thermal enhancement factor (TEF). The study encompasses variations in opening angles (θ = 0°, 5°, 10°, 15°) and pitch ratios (PR = P/H = 15, 30, 45) to determine their impact on the overall system performance. The findings reveal that the punched curved rectangular winglet VGs effectively induce mixed vortices, leading to an enhancement in local heat transfer rates. However, the presence of fluid jets hinders the formation of other vortices. Compared to a smooth tube, the maximum TEF also experiences a 26 % rise. To validate the findings, the field synergy principle and entropy generation theory was utilized.

Numerical modelling and experimental investigations to predict the tool wear of copper electrodes during µ-EDM process

The micro electrical discharge machining (µ-EDM) process is one of the most widely used techniques to produce miniaturized components in micro-electro mechanical system (MEMS) applications due to its inherent advantages. This work investigates the wear phenomena and the morphology of the copper electrodes during the micro-die sinking process. A numerical model of a single spark is developed assuming the Gaussian distribution of heat flux to estimate the crater dimensions formed in the copper tool electrode (tool wear) used as a result of electric discharge. The crater dimension attained from the ABAQUS finite element model is validated with experimental results using a single spark test setup. Moreover, the effect of input parameters namely capacitance and voltage on the electrode wear rate and surface roughness is also studied. The crater dimensions from the single discharge study are used to formulate the wear model for different possibilities of crater distribution, such as non-overlapping craters, craters with less than 30 % overlap, and 50 % overlap. The electrode wear rate (EWR) also displayed a decline from 20.4 % to 11.6 % and further to 8 % when the overlap was permitted up to 30 % and up to 50 % for the wear model respectively. The developed model results are further compared with experimental results in terms of the electrode wear rate and depth of erosion and the deviations are found to be 20.33 % and 20.55 % respectively

High-throughput single cell analysis using multi-focus Raman spectroscopy under randomly interleaved scattering projection

Raman microspectroscopy is a powerful tool for label-free monitoring of single-cell dynamics. However, the traditional single-point acquisition mode is extremely inefficient because it only analyzes one cell at a time. We propose a method that combines multi-focus Raman excitation with random interleaving of scattering projections. The approach uses a time-sharing multi-focus array to simultaneously excite multiple biological cells and synchronously projects their Raman spectra into a single spectral channel with varying shifts. The spectral shifts of the cells are randomly interleaved during data acquisition, resulting in a sequence of mixed spectra from which a compressive sensing method is utilized to reconstruct the time-lapse Raman spectra of the individual cells. The method’s feasibility and performance are validated by numerical modeling and experimental investigations into biological spore germination. The results indicated that the throughput of single cell analysis can be increased by up to a factor of 15. The reconstructed spectra of the individual cells demonstrated exceptional fidelity, faithfully capturing the cellular changes in the individual cells. The developed technology paves the way towards high-throughput, label-free monitoring of living single cells, which has promising applications in cell biology.

Prediction of the keyhole TIG welding-induced distortions on Inconel 718 industrial gas turbine component by numerical-experimental approach

Welding technologies represent a paramount joining process for ensuring the quality and reliability of critical industrial components; therefore, their innovation constitutes a driving force in realizing increasingly competitive products. A recently developed technology is the keyhole TIG welding, a new high energy–density alternative to the conventional TIG process. A key role in improving innovative manufacturing processes such as the keyhole TIG is covered by numerical simulation; indeed, it allows the development of a process digital twin able to support decisions and work as a predictive tool. Within this framework, the paper deals with the numerical-experimental investigation of the keyhole TIG technology, successfully employed on a simplified mock-up of an industrial gas turbine component consisting of two 6.5-mm-thick Inconel 718 rings. Numerical analysis aimed at predicting welding-induced distortions was performed employing two different computational approaches, namely the moving heat source and the simplified imposed thermal cycle methods. The numerical-experimental comparison of the results demonstrates an innovative approach in the field of the current keyhole TIG numerical simulation since, besides verification of numerical thermal analysis, further substantial validation of the post-weld distortion predictions is provided through comprehensive three-dimensional experimental data. Moreover, the comparative assessment of the two computational approaches and experimental evidence revealed that the imposed thermal cycle method implementation does not compromise the accuracy of welding distortion forecasting in industrial applications such as that investigated. Therefore, it can be regarded as a valuable tool for supporting the process engineer in designing the ideal set-up to comply with a variety of industrial requirements, among them strict design tolerances.

Numerical Simulation and Experimental Investigation of Microstructure Evolution and Flow Behavior in the Rheological Squeeze Casting Process of A356 Alloy

Numerical Simulation and Experimental Investigation of Microstructure Evolution and Flow Behavior in the Rheological Squeeze Casting Process of A356 Alloy