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Laser peen forming (LPF) is an appealing technique for forming metal sheets using high-energy, shortduration laser pulses. The deformation of the target metal plate is closely related to the magnitude and distribution of laser-induced residual stress. Consequently, the relationship between process parameters and residual stress is worth researching. In this research, two process parameters in LPF, laser energy and coverage ratio (spot distance essentially), and one workpiece parameter, plate thickness, were examined through an element method (FEM) of multiple square-spot laser shock peening (SSLSP). Corresponding experiments of SSLSP on aluminum alloy 2024-T351 test blocks were conducted, together with an X-ray diffraction (XRD) residual stress measurement and a surface morphology observation. The FEM simulation and experimental results show that congested laser spots had a significant influence on the magnitude of compressive residual stress; higher laser energy was beneficial to the depth of the compressive stress layer but could decrease its magnitude. Therefore, for better forming ability, higher laser energy and a higher coverage ratio are beneficial; for surface strengthening, laser energy should not be too large, and the coverage ratio should be larger than 100% to ensure that the residual stress on the treated surface is compressive, resulting in better surface integrity. [ABSTRACT FROM AUTHOR]

Recently, deteriorated masonry structures aged over 30 years have shown serious structural problems. Simple and rapid maintenance plans are urgently needed for aging masonry structures. Polyurea (PU) is an effective retrofitting material for aging structures due to its easy spray application. This process saves time, reduces costs, and allows the structure to remain in use during retrofitting. However, a general PU is not suitable for retrofitting aged masonry and concrete structures due to its low stiffness. In this study, stiff-type polyurea (STPU) was selected as the reinforcement material for masonry structures. It was developed by modifying the chemical mix of general PU to improve stiffness. To evaluate the strengthening effect of STPU on masonry members under static loading, tests were conducted. The flexural load capacity of masonry beams with STPU-sprayed surfaces was assessed. Three different types of STPU applications were used to select the most efficient strengthening method. Reinforcing masonry structures with STPU allows brittle failure modes to achieve ductile behavior. This improves their structural performance under lateral stresses. The experimental data were used to calibrate FEM models for simulation. These models can be used for future parametric studies and masonry structural design. [ABSTRACT FROM AUTHOR]

This work presents an optimum methodology for producing friction stir spot welding (FSSW) joints using a detachable consumable pin. The study is carried out by welding two AA6061-T6 sheets using a consumable pin of the same material attached to the H13 steel tool. Three methods for attaching the consumable pin to the tool are explored: (1) push-fitting the pin in an indentation on the tool, (2) adhesively bonding the pin to the tool with a cyanoacrylate adhesive, and (3) adhesively bonding the pin to the tool with a thermosetting glue. After welding, the pin gets detached and assimilated into the workpiece. Cyanoacrylate adhesive–bonded consumable pin was the most effective in producing exit-hole–free FSSW joints with good joint strength. The use of lubricants along with adhesive-bonded consumable pins resulted in a reduction of energy requirement by 35 − 42% without compromising joint strength. Optimization was carried out using data from experiments as well as finite element method simulations. For simulating the lap shear test, the Cockcroft-Latham damage model was used. The optimum process parameters for obtaining the maximum joint strength were a rotational speed of 900 revolutions per minute and a plunge rate of 15 mm/min. Based on the study, a strategy for batch production is also proposed for enhancing productivity. [ABSTRACT FROM AUTHOR]

This study investigates the influence of ferrite shape modifications on the performance and noise characteristics of an induction cooktop. The goal is to optimize the air gap dimensions between ferrites and cookware, enhancing efficiency while managing noise levels. Using finite element method (FEM) simulations, we analyze the spatial distribution of magnetic forces and their harmonics. Eight ferrite shape models were examined, focusing on both outer and inner air gaps. Model #8 (reduced outer air gap) and Model #9 (reduced inner air gap) were experimentally validated. Noise measurements indicated that Model #8 reduced 120 Hz harmonic noise components, while Model #9 increased them due to enhanced excitation forces. Current measurements confirmed that Model #9 achieved higher efficiency, with RMS current reduced to 94.54% of the base model. The study reveals a trade-off between performance and noise: inner air gap reduction significantly boosts efficiency but raises noise levels, whereas outer air gap reduction offers balanced improvements. These findings provide insights for optimizing induction cooktop designs, aiming for quieter operation without compromising efficiency. [ABSTRACT FROM AUTHOR]

Shot peening is a commonly used method of finishing machine elements in the manufacturing process. One variation of shot peening is the impulse shot peening. This paper presents the influence of impulse shot peening technological conditions on the surface roughness (parameters Ra and Rt), topography, and microhardness. The FEM was used to determine the S11 stresses. In the experiment and simulation tests, AZ31 and AZ91HP magnesium alloy samples were used. Variable parameters in the impulse shot peening process were impact energy E (15–185 mJ), ball diameter d (3–15 mm), and impact density j (3–44 mm−2). As a result of the tests carried out, it was found that after impulse shot peening, the surface topography is change, microirregularities are flattened, and numerous depressions are formed, which can be potential lubrication pockets. The 2D surface roughness parameters for most impulse shot peening conditions are lower than for the pre-machining. The roughness parameters for magnesium alloy AZ91HP are lower than for AZ31. This is most likely due to the lower elongation A. The microhardness after impulse shot peening increased by 20 to 87 HV. As a result of FEM of the impulse shot peening, compressive stresses S11 were created in the surface layer. The depth of occurrence of S11 stresses is from 1.5 to 3.5 mm, and their values for the AZ91HP magnesium alloy samples are 10 to 25% lower than for the AZ31 alloy samples. The most favorable results of the tested properties of the surface layer were obtained for E = 100 mJ, d = 10 mm, and j = 11 mm−2. The abstract serves both as a general introduction to the topic and as a brief, non-technical summary of the main results and their implications. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hematite (α -Fe2O3) is widely used in sensor sensitization due to its excellent optical properties. In this study, we present a sensitivity-enhanced surface plasmon resonance alcohol sensor based on Fe2O3/Au. We describe the fabrication process of the sensor and characterize its structure. We conduct performance testing on sensors coated multiple times and use solutions with the same gradient of refractive indices as the sensing medium. Within the refractive index range of 1.3335–1.3635, the sensor that was coated twice achieved the highest sensitivity, reaching 2933.2 nm/RIU. This represents a 30.26% enhancement in sensitivity compared to a sensor with a pure gold monolayer film structure. Additionally, we demonstrated the application of this sensor in alcohol concentration detection by testing the alcohol content of common beverages, showing excellent agreement with theoretical values and highlighting the sensor's potential in food testing. [ABSTRACT FROM AUTHOR]

We present advancements in a finite element method for computing the physical properties of magnetic microcalorimeters (MMCs). Utilizing the COMSOL package, we conducted 3D simulations of a meander-shaped Nb coil with a realistic geometry. The resulting magnetic field distribution showed good agreement with a previous 2D simulation and revealed non-negligible differences at the side edge of the sensor material. Employing the simulation results, we calculated the MMC properties and compared them with previous measurements. Our calculated values closely align with the measured values for the sensor magnetization, the pulse heights from alpha detection, and the coil inductance. [ABSTRACT FROM AUTHOR]

A multiscale model is developed for vertically aligned carbon nanotube (CNT)-based membranes that are made for water purification or gas separation. As a consequence of driving fluids through the membranes, they carry stress waves along the fiber direction. Hence, a continuum mixture theory is established for a representative volume element to characterize guided waves propagating in a periodically CNT-reinforced matrix material. The obtained coupled governing equations for the CNT-based composite are found to retain the integrity of the wave propagation phenomenon in each constituent, while allowing them to coexist under analytically derived multiscale interaction parameters. The influence of the mesoscale characteristics on the continuum behavior of the composite is demonstrated by dispersion curves of harmonic wave propagation. Analytically established continuum mixture theory for the CNT-based composite is strengthened by numerical simulations conducted in COMSOL for visualizing mode shapes and wave propagation patterns. [ABSTRACT FROM AUTHOR]

Machining hard materials, such as tool steel and tungsten carbide, involves high cutting forces and temperatures that lead to severe tool wear. Frequent tool changes owing to tool wear increase costs and decrease productivity, degrading the surface quality and accuracy of machined parts. Various studies have explored approaches to reduce tool wear in the machining of hard materials, such as micropatterns on the rake face of cutting tools, ultrasonic elliptical vibration cutting, and built-up-edge at the end of the tool. However, limited research has been conducted on the microstructures and patterns of the built-up edges. This study proposes a methodology to stabilize the built-up edge at the end of a tool with microstructures and patterns. The chip morphology and behavior were simulated using FEM software to determine the machining conditions and microstructure required to maintain a constant built-up edge at the tool tip. Several microstructures were machined at the edge of the cutting tool, and orthogonal cutting experiments were conducted to validate the simulation. Additionally, tool wear was evaluated for the tool structure and machining conditions. [ABSTRACT FROM AUTHOR]

Numerical solutions in the field of modelling of the welding process constitute significant support for the production process and are one of the most difficult to perform in terms of the complexity of physical phenomena in the welding process. This is especially true when commercial software such as Abaqus, Ansys, etc. is used in the analysis, where welding conditions are not directly reflected in the modules of the software. This work is focused on the development of mathematical models of a moveable heating source taking into account various welding techniques. The simulations are carried out in Abaqus software, which, in its basic form, does not allow simulations of welding process. The presented work contains the developed mathematical and numerical models necessary for conducting numerical studies in the field of the analysis of the welding process. The presented DFLUX subroutine allows the implementation of any mathematical model of the heating source and modelling of the movement of the source along any trajectory. As a part of the research, mathematical models are developed for three completely different welding techniques: fillet welding, circumferential welding and spiral welding. Each of these three methods requires the use of a completely different approach. Based on the developed mathematical and numerical models, testing calculations are performed. Selected calculations are compared with experimental results presented in the literature. The presented results of calculations allow for the confirmation of the correctness of the developed mathematical and numerical models of heat source power distribution. [ABSTRACT FROM AUTHOR]

On the DIFA II loom, which is a special air jet weaving machine for the production of drop-stitch fabrics with a variable distance, so called 3D or distance fabrics, the main component of the interconnecting yarn creation mechanism is a take-up bar. During the yarn loops formation, the take-up bar is exposed to high loads, while being pulled by a mechanism into a limited wedge-shaped space between the two plain weave faces, thus the bending stiffness of the bar is crucial. Deflection of the bar combined with an elongation of the warp yarns results in an uneven load distribution with an undesirably loosened central section of warp yarns. This phenomenon is deeply examined in this paper. The classical model of a thin beam loaded by a distributed linear force cannot be applied in this case. In this work are new take-up bar designs considering usage and production aspects. The take-up bar variants with different warp yarns stiffness were analysed. A numerical model was created, and calculations were performed by the FEM solver NX Nastran as a 1D solution. Additionally, the problem was analysed analytically and it shows an analogy with a beam on an elastic foundation. The theoretical Winkler's model was used and an idealised analytical solution was found. In both methods, comparable maximal deflections of the take-up bar and widths of loosened yarns were found. The obtained results of the bar deflection were validated with a good agreement on the DIFA II loom using new take-up bars. [ABSTRACT FROM AUTHOR]

Precision machining operations often lead to the failure of protective coatings on cutting tools due to common issues such as cracking, delamination, and peeling from cyclic impacts. While material selection and structural design are crucial for enhancing impact resistance, they primarily focus on static performance with limited consideration from the dynamic sights. This paper presents a novel dynamic design method for coatings, viewed through the lens of stress waves. We investigate the propagation behavior of stress waves in TaN/TiN and CrN/TiN coatings with layered structures. Our findings indicate that the attenuation of stress waves is dominated by the physical properties on both sides of the interface and the stride length. For interfaces with similar physical properties, the attenuation of stress waves is insensitive to the stride length, while for interfaces with different physical properties, the attenuation is regulated by the ratio of single-layer thickness to the full width at half maximum of the stress wave. These insights offer a strategy for extending the life of coatings and improving process safety under dynamic shocks.

In this study, an effective numerical model was developed for the calculation of the deformation of laser-welded 3 mm 304L stainless steel plates with different gaps (0.2 mm, 0.5 mm, and 1.0 mm). The welding deformation would become larger when the welding gaps increased, and the largest deformation values along the Z direction, of 4 mm, were produced when the gap value was 1.0 mm. A larger plastic strain region was generated in the location near the weld seam, since higher plastic deformation had occurred. In addition, the tensile stress model was also applied at the plastic strain zone and demonstrated that a larger welding gap led to a wider residual stress area. Based on the above results, inherent deformations for butt and corner joints were calculated according to inherent strain theory, and the welding formation for the complex structure was calculated with different gaps. The numerical results demonstrated that a larger deformation was also produced with a larger welding gap and that it could reach the highest value of 10.1 mm. This proves that a smaller welding gap should be adopted during the laser welding of complex structures to avoid excessive welding deformation. [ABSTRACT FROM AUTHOR]

Because dike propagation depends on stress state, the geometry of dikes can be used to make inferences about crustal stress conditions during emplacement. Early work relied on analytical solutions for stress in a two-dimensional elastic medium with a pressurized circular magma chamber and biaxial far-field stress. The principal stress trajectories in this classical model depend on the ratio of deviatoric stress magnitude to chamber pressure. Assuming dikes follow principal stress trajectories and bounding plausible magma chamber excess pressures lead to estimates of deviatoric stress magnitudes from the map pattern of dikes. Mériaux and Lister (2002) pointed out that this approach ignored stresses due to the magma-filled dikes themselves, which significantly alter predicted dike trajectories. They estimated deviatoric stresses 2 to 5 times previous estimates. However, Mériaux and Lister (2002) assumed the pressure distribution within the dike rather than computing it from viscous magma flow. We revisit this simplification using a 2D model which fully couples a linear elastic host rock with a pressurized chamber and a fluid-filled dike, assuming the lubrication approximation for viscous flow. This model is solved using the finite element method (FEM). Ensuring that dike propagation is stable limits the dike-tip cavity pressure for realistic fracture toughness. We find that computed trajectories fall between the classical principal stress and Mériaux and Lister (2002) trajectories for given regional stress and chamber pressure conditions. This leads to deviatoric stress magnitude estimates that are 1 to 2 times the classical estimates, and 1/2 to 1/3 the Mériaux and Lister (2002) estimates. We also explore the consequences of chamber depressurization due to magma outflow during dike propagation. For a given melt compressibility, the resulting trajectories align more closely with those obtained from the classical model, compared to those obtained assuming a constant chamber pressure. At higher ratios of tectonic stress to chamber pressure, the trajectories are nearly identical. In both the constant pressure and depressurizing chamber cases, our results suggest that realistic magma pressure profiles within a dike lead to smaller estimated ratios of deviatoric stress to chamber pressure than found by Mériaux and Lister (2002). Future work should extend dike propagation models to three dimensions, and more thoroughly explore effects of magma compressibility. [ABSTRACT FROM AUTHOR]

The paper presents a rigorous analytical approach to predicting the load–settlement behavior of axially loaded piles embedded in sandy soils, adopting the advanced SANISAND model. The problem of the soil state around the pile during loading is formulated as a system of first-order ordinary differential equations, which can be solved as an initial value problem. The derived load–settlement (t–z) curve is then implemented into the load-transfer method to determine the pile's load–settlement behavior in sands and the deformation mechanism of the soil around the pile during axial loading. To verify the proposed analytical approach, a FEM simulation is performed with a user-defined subroutine, demonstrating its capacity to capture the dilatancy behavior of sands as the pile moves downwards. Additionally, a parametric analysis is conducted to assess the influence of the initial void ratio on the stress–strain relationship of the sandy soil around the pile during the loading process. The proposed analytical approach is also compared with a well-established finite-element model and a centrifuge test. The results indicate that the present approach can well predict the elastoplastic load–settlement response of the pile and reflect important phenomena observed from pile tests. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive approach aimed at developing a coupled process-structure simulation that integrates anisotropic and elastoplastic material behavior for plastic components manufactured through Fused Filament Fabrication (FFF) 3D printing. The simulation incorporates material orientation considerations, linking the process simulation with structural simulation. Subsequently, stress and strain values from the simulations are compared with the test results. Moreover, the fracture behavior of components manufactured in this way is also taken into account in relation to material orientation. The executed simulations have yielded successful outcomes, affirming the efficacy of the anisotropic and elastoplastic simulation across all strand orientations. Special attention is paid to the application of the method. Here, the simulation method introduced in this contribution with the approaches for describing the material behavior under mechanical load can be used in the future in the dimensioning of FFF manufactured plastic components to predict the deformation behavior and failure, especially under consideration of a well economic and efficient virtual product development. [ABSTRACT FROM AUTHOR]

Within the scope of this study, the macroscopic temperature distribution in the steady-state temperature condition during Field Assisted Sintering Technique/Spark Plasma Sintering (FAST/SPS) in functionally graded materials (FGM) was investigated. The sample material exhibited a diameter of 50 mm and a thickness of 9 mm. The FGM samples were composed of steel X2CrMnNi 16-7-6 and Mg-PSZ ceramic (MgO partly stabilized ZrO 2). By varying the sintering tool setup, a specific modification of the macroscopic temperature distribution within the sample material and the sintering tool was achieved. The aim of the modifications was to optimize the temperature gradients in order to allow for the simultaneous compaction of all FGM layers under ideal circumstances. This involves achieving enhanced ceramic densification without inducing steel melting. Finite element method (FEM) simulations were carried out to get information about the temperature distribution within the sample material and the sintering tool. Furthermore, for this propose, thermocouple temperature measurements were conducted at various measurement points on pre-sintered FGM within the specific sintering tool setup. Additionally, all findings regarding the temperature distribution within the sample material and the sintering tool were compared with results concerning the temperature distribution from the microstructural and mechanical characterization of the center and edge regions of the FGM samples. The FGM samples exhibited a significant increase in temperature from the center to the edge in the radial direction depending on the used sintering tool setup. While the FGM samples showed only minor vertical temperature gradients in the center, the highest vertical temperature gradients were determined at the edge of the FGM sample using an asymmetric sintering tool setup. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An investigation into the evolution of temperature and stress fields, as well as the phase transformation in marine steel EH36 during multi-pass welding, and their subsequent effects on Charpy impact toughness, remains in great lack. In this study, submerged arc welding (SAW) was employed to carry out multi-pass welding on EH36 steel plates, followed by the low-temperature toughness test of weldments. Comsol software version 6.2 and finite element analysis are utilized to simulate the evolution of the microstructure, temperature, and residual stress fields throughout the multi-pass welding process. As welding progressed, the heat absorption along the vertical direction was enhanced; in contrast, a decrease is observed in the horizontal direction away from the heat source. This complicated temperature history favors the bainite transformation in the vicinity to the heat source, whereas areas more remote from the weld zone exhibit a higher prevalence of acicular ferrite due to the reduced cooling rate. The concentration of residual stress is predicted to occur at the boundary of the melt pool and at the interface between the weld and the heat-affected zone, with the greatest deformation observed near the fusion line at the top surface of the model. Furthermore, multi-pass welding may alleviate the residual stress, especially when coupled with the formation of acicular ferrite upon cooling, leading to improved low-temperature impact toughness in regions remote from the heat source. These findings offer valuable insights for the design and optimization of multi-pass welding in future applications. [ABSTRACT FROM AUTHOR]

Machinery traffic is associated with the application of stress onto the soil surface and is the main reason for agricultural soil compaction. Currently, probes are used for studying the stress propagation in soil and measuring soil stress. However, because of the physical presence of a probe, the measured stress may differ from the actual stress, i.e. the stress induced in the soil under machinery traffic in the absence of a probe. Hence, we need to model the soil-stress probe interaction to study the difference in stress caused by the probe under varying loading geometries, loading time, depth, and soil properties to find correction factors for probe-measured stress. This study aims to simulate the soil-stress probe interaction under a moving rigid wheel using finite element method (FEM) to investigate the agreement between the simulated with-probe stress and the experimental measurements and to compare the resulting ratio of with/without probe stress with previous studies. The soil was modeled as an elastic-perfectly plastic material whose properties were calibrated with the simulation of cone penetration and wheel sinkage into the soil. The results showed an average 28% overestimation of FEM-simulated probe stress as compared to the experimental stress measured under the wheel loadings of 600 and 1,200 N. The average simulated ratio of with/without probe stress was found to be 1.22 for the two tests which is significantly smaller than that of plate sinkage loading (1.9). The simulation of wheel speed on soil stress showed a minor increase in stress. The stress over-estimation ratio (i.e. the ratio of with/without probe stress) noticeably increased with depth but increased slightly with speed for depths below 0.2 m.

The brake system must be reliable and display unchanging action throughout its use, as it guards the health and life of many people. Properly matched friction pair, a drum, and a brake pad have a great impact on these factors. The brake pads are far more complex components. New technologies make it possible to develop materials with various compositions and different proportions and connect them permanently in fully controllable processes. This elaboration shows that all these factors have a greater or lesser impact on the coefficient of friction, resistance to friction wear and high temperature, and the brake pad’s operating life. The friction materials are required to provide a stable coefficient of friction and a low wear rate at various operating speeds, pressures, temperatures, and environmental conditions. The aim of this work is therefore to investigate the possibility of using a Finite Element Analysis (FEA) approach to evaluate the braking performance of a heavy-duty elevator with different non-conventional pad materials including Composite Carbon fiber reinforced, Composite Epoxy SMC and SiC (silicon carbide). The results show that the performance of SiC (silicon carbide) is better than two other materials. In the braking system with SiC, the required time for stoppage of the system is lower than two other materials.

The present paper proposes a new approach for the thermomechanical analysis of small satellites. In the first stage, the heat fluxes acting on the exterior surfaces of the assembly are evaluated with the support of the CubeSat Wizard. The orbital parameters employed ensure adequate radiation heat transfer. Afterwards, the temperature distribution of the entire structure is evaluated with the support of the LISA thermal transient environment. The most critical load case is further use for calculating stress and displacement in a static analysis. Two configurations of CardSat nanosatellites are included in the study for comparison.

With the increasing of tunnel mileage, one of the most vital problems of broad-scale structures is the intelligent identification and location of structural defects, which require massive data storage capacity and high data processing efficiency. The full-field point cloud data collected by terrestrial laser scanning (TLS) can be extracted to construct three-dimensional measured models more accurately, therefore, the fusion of TLS and the finite element method (FEM) is particularly beneficial to the deformation analysis of tunnel structures. This paper combines numerical simulation and full-field measurement to interactively verify the reliability of deformation analysis based on FEM simulation and point cloud processing. The innovation of this paper is that a three-dimensional FEM is validated through the measured point cloud data of the tunnel structure. The result of this study indicated that FEM simulation and the structural health monitoring analysis are consistent. [ABSTRACT FROM AUTHOR]

Cathodic protection is an electrochemical technique used to control the corrosion of metals. It does this by sending a proper amount of current equal to the current required by the cathodic processes at the protection potential. One of the chemical effects of cathodic protection is a local pH increase at the surface, which is an important factor in the reduction of corrosion rate, as carbon steel may work in a passive condition. In the present study, a tertiary current distribution finite element method model is introduced. A dynamic boundary condition is considered, by defining a Fe anodic Tafel slope as a pH function, and oxygen reduction reaction limiting current density as a function of available oxygen at the cathode surface. The model has been validated by direct pH measurement during a short‐term polarization test, and subsequently used to predict the pH and the available oxygen at the cathode surface for long‐term condition. [ABSTRACT FROM AUTHOR]

Skin electroporation for drug delivery involves the application of Pulsed Electric Fields (PEFs) on the skin to disrupt its barrier function in a temporary and non-invasive manner, increasing the uptake of drugs. It represents a potential alternative to delivery methods that are invasive (e.g. injections) or limited. We have developed a drug delivery system comprising nanocomposite hydrogels which act as a reservoir for the drug and an electrode for applying electric pulses on the skin. In this study, we employed a multi-scale approach to investigate the drug delivery system on a mouse skin model, through electrical measurements, numerical modeling and fluorescence microscopy. The Electrical properties indicated a highly non-linear skin conductivity behavior and were used to fine-tune the simulations and study skin recovery after electroporation. Simulation of electric field distribution in the skin showed amplitudes in the range of reversible tissue electroporation (400–1200 V/cm), for 300 V PEF. Fluorescence microscopy revealed increased uptake of fluorescent molecules compared to the non-pulsed control. We reported two reversible electroporation domains for our configuration: (1) at 100 V PEF the first local transport regions appear in the extracellular lipids of the stratum corneum, demonstrated by a rapid increase in the skin's conductivity and an increased uptake of lucifer yellow, a small hydrophilic fluorophore and (2) at 300 V PEF, the first permeabilization of nucleated cells occurred, evidenced by the increased fluorescence of propidium iodide, a membrane-impermeable, DNA intercalating agent. Skin electroporation for transdermal drug delivery assessed by electrical measurements, numerical modeling and delivery of fluorescent molecules. [Display omitted] • Nanocomposite hydrogels function as drug reservoirs and electrodes. • Integrated electrical measurements, numerical modeling & molecule delivery. • Skin resistance drops with electric field strength. • Stratum corneum barrier disruption at 100 V. • Cell membrane permeabilization at 300 V in viable skin. [ABSTRACT FROM AUTHOR]

Soils are known to be inherently anisotropic, resulting in complex responses to loading. This paper aims to develop an elastoplastic solution for the undrained expansion of a cylindrical cavity in sands adopting a non‐associated and anisotropic model, SANISAND. The rigorous derivation of the stress‐strain state of the soil element is provided following a standardized solving procedure. The dilatancy and crushing of the soil are invoked in the three‐dimensional cavity expansion solution by adopting the critical state soil mechanics and limiting compression curve, respectively. By combining this with a governing equation that considers the undrained condition, the stress‐strain state of the surrounding soil around the cavity can be determined. A subroutine is then implemented into the ABAQUS FEM simulation to verify the solution. The solutions are also validated against those based on an isotropic model, and anisotropic sand is used to investigate the effects of the initial effective mean stress, at‐rest coefficient of earth pressure, and overconsolidation ratio on the stress distribution, stress path, and boundary surfaces. [ABSTRACT FROM AUTHOR]

Silver nanoparticles on a glass substrate are experimentally investigated by aperture scanning near-field optical microscopy (a-SNOM). To understand the experimental results, finite-element-method simulations are performed building a theoretical model of the a-SNOM geometry. We systematically vary parameters like aperture size, aluminum-coating thickness, tip cone angle, and tip-surface distance and discuss their influence on the near-field enhancement. All these investigations are performed comparatively for constant-height and constant-gap scanning modes. In the end, we establish a reliable and stable optical model for simulating a-SNOM measurements, which is capable of reproducing trends observed in experimental data. [ABSTRACT FROM AUTHOR]

Machinery traffic is associated with the application of stress onto the soil surface and is the main reason for agricultural soil compaction. Currently, probes are used for studying the stress propagation in soil and measuring soil stress. However, because of the physical presence of a probe, the measured stress may differ from the actual stress, i.e. the stress induced in the soil under machinery traffic in the absence of a probe. Hence, we need to model the soil-stress probe interaction to study the difference in stress caused by the probe under varying loading geometries, loading time, depth, and soil properties to find correction factors for probe-measured stress. This study aims to simulate the soil-stress probe interaction under a moving rigid wheel using finite element method (FEM) to investigate the agreement between the simulated with-probe stress and the experimental measurements and to compare the resulting ratio of with/without probe stress with previous studies. The soil was modeled as an elastic-perfectly plastic material whose properties were calibrated with the simulation of cone penetration and wheel sinkage into the soil. The results showed an average 28% overestimation of FEM-simulated probe stress as compared to the experimental stress measured under the wheel loadings of 600 and 1,200 N. The average simulated ratio of with/without probe stress was found to be 1.22 for the two tests which is significantly smaller than that of plate sinkage loading (1.9). The simulation of wheel speed on soil stress showed a minor increase in stress. The stress over-estimation ratio (i.e. the ratio of with/without probe stress) noticeably increased with depth but increased slightly with speed for depths below 0.2 m. [ABSTRACT FROM AUTHOR]

This paper presents static modelling and simulation of a spherically-shaped hyperelastic balloon actuator subjected to an angular rotation with an internally applied air pressure. These actuators are extensively used in soft robotics because its safe and flexible nature. The balloon actuator is a pneumatic-type actuator made of a polymeric material. A continuum mechanics-based analytical modelling and Finite element method-based simulation are performed to predict the response of the actuator for a given angular rotation with internally applied air pressure. The proposed modelling framework is subsequently utilised to perform the parametric studies for varying pressure, thickness, and rotational speed of the actuator. Various elastic instability curves are also obtained to examine the critical inflation of the rubber balloon actuator. The analytical findings agree well with the FEM simulations. [ABSTRACT FROM AUTHOR]

A Bayesian machine learning (ML) framework was introduced for the comprehensive characterization of bond wires within insulated gate bipolar transistor (IGBT) modules under the influence of thermomechanical loadings. The primary objective of this work was to predict two critical performance metrics, namely, equivalent plastic deformation (EPD) and the number of cycles to failure (Nf). At the core of our investigation was the dependable acquisition of training data via finite element method simulations. Based on the results, exceptional predictive accuracy was achieved, as evidenced by the impressive R-squared values of 0.962 for EPD and 0.927 for Nf, both of which are obtained from the Bayesian ML model. The high performance of the Bayesian model can be attributed to its ability to effectively capture complex relationships within the data while simultaneously being robust in handling uncertainties, rendering it suitable for situations characterized by limited datasets. Furthermore, it was revealed that the weight functions of the input parameters were significantly influenced by the values of the output targets, illustrating the distinct dependencies between each output target (EPD and Nf) and the relevant input features. These findings contribute to a deeper comprehension of the intricate interactions between input parameters and output metrics, ultimately aiding in the development of more precise and dependable models for bond wire characterization in IGBT modules. [ABSTRACT FROM AUTHOR]

In contrast to homogeneous mechanical load according to IEC 61215, photovoltaic modules in the field are mainly exposed to inhomogeneous loads like snow or wind. This paper deals with such inhomogeneous loads using computational fluid dynamics and finite element method simulations. Temperatures different to room temperature and the choice of encapsulates have significant influences on the thermomechanics of a photovoltaic module in case of snow load. Polyolefin is the encapsulant with the lowest storage modulus and has the lowest overall stress in solar cells and glass down to −30°C. Furthermore, with colder temperatures, the first principal stress decreases in solar cells but increases in the glass. For wind loads, the impact of module orientation, wind direction, module inclination angle, and wind speed is analyzed. A crosswind scenario is found to be most critical. Additionally, as a rule of thumb, higher module inclination angles result in higher stresses. Finally, general thermomechanical rules are extracted allowing for a deeper understanding of the underlying effects and therefore help to build more robust modules in the future. [ABSTRACT FROM AUTHOR]

This paper investigates the behavior of transverse defects under significant total strain in conditions of complex vortex metal flow implemented through the radial shear rolling (RSR) method. The aim of this study is to assess the applicability of RSR processing for the in-depth transformation of small ingots of special steel into bars, particularly for the manufacturing of structural elements in specialized construction projects such as nuclear power plants. Although a substantial total strain is anticipated to enhance the steel structure and contribute to defect closure, the question of the development or closure of potential casting defects remains unclear. To address this issue, model tests were conducted to simulate the implementation of RSR processing. Defect behavior data under very complex vortex metal flow and high strain conditions were obtained for the first time and have scientific merit. A small steel ingot with a 32 mm diameter, containing a simulated artificial defect in the form of a transverse through-hole with a 5 mm diameter, was employed. During rolling, the workpiece diameter was progressively reduced by 2 mm with each subsequent pass, reaching a final diameter of 20 mm. Additionally, to provide a more detailed visualization of the defect evolution process, the same defect was modeled in an aluminum bar over six passes, and changes in defect volume and shape were analyzed after each pass. A highly detailed 3D visualization of the actual defect evolution was achieved based on cross-sections from experimental workpieces. These data corresponded to the total strain levels obtained by finite element method (FEM) simulation. Notably, a consistent similarity was observed between the test results for both metals, revealing a reduction in defect volume of up to 67.7%. The deformational welding of defects in the outer sections, encompassing one-third of the rod's radius, occurred in the initial passes. However, defects in the axial zone of the rods remained unclosed, lengthening and gradually decreasing proportionally to the elongation of the rod, akin to conventional rolling. Consequently, the radial shear rolling (RSR) method is unsuitable for ingots with substantial discontinuities in the axial zone post-casting. Nevertheless, the method ensures the total welding of defects located in the outer zones of the ingots, even with minor applied deformations and a slight decrease in the diameter of the deformed ingot. Such data were obtained for the first time and should contribute to future investigations in this field. [ABSTRACT FROM AUTHOR]

Biofilms are ubiquitous at interfaces of natural and technical origin. Depending on type and application, biofilm formation is desired or has to be prevented. Therefore, reliable detection of initial biofilm growth is essential in many areas. One method of biofilm monitoring is the electrochemical impedance spectroscopy. Among other factors, this method is heavily dependent on the electrode geometry. In order to achieve a high measurement sensitivity, the electrode size must be chosen according to the biofilm that is to be measured. This paper presents an approach for simulating and modeling the optimal electrode geometry for a specific biofilm. First, a geometric model of a biofilm with up to 6000 individual bacteria is generated. The simulated impedances are used to calculate which electrode geometry maximizes sensitivity depending on the biofilm height. In the chosen example of an E. coli biofilm in a nutrient solution, the optimum size of an interdigital electrode (bar gap equals width) was 2.5 µm for a biofilm height of up to 2 µm. The used algorithms and models can be simply adapted for other biofilms. In this way, the most sensitive electrode geometry for a specific biofilm measurement can be determined with minimal effort. [ABSTRACT FROM AUTHOR]

Thermal interface materials (TIMs), as important materials for heat dissipation of insulated gate bipolar transistor (IGBT) modules, degrade under long-term thermal cycling, resulting in elevated junction temperatures and threatening the safe operation of IGBT modules. In consideration of the thermal coupling effect in IGBT modules, this paper proposes a three-dimensional thermal network model characterizing the TIM degradation. An IGBT module with the TIM is adopted to establish the finite element method (FEM) model, in which the TIM layer is divided into regular areas. The thermal network is established by simulating the heat transfer paths. The thermal impedance in each path is extracted according to the heat flow through its area considering the TIM degradation. Thereby, the impact of thermal coupling and TIM degradation on junction temperature of IGBT modules could be characterized. Furthermore, the proposed thermal network is verified by simulation from calculation accuracy of junction temperature and TIM temperature.

The use of 3D glass as a cover will significantly improve the stylish sense of the product and provide a wider display interface. However flexible film are notoriously difficult to fully conform to non‐developable surface such as spheres. The greatest challenge when trying to attaching flexible display to 3D spherical glass is avoiding wrinkling phenomenon at the edge of flexible display. In this paper the finite element method is used to study the optimization of the stack‐up to avoid obvious wrinkling phenomenon. We confirm that the modulus and thickness of Optical Clear Adhesive(OCA) between flexible modulus and 3D glass cover have decisive impact on the formation of wrinkles. A wrinkle‐free watch product was successfully fabricated by replacing the low‐modulus OCA with high‐modulus OCA or by reducing the thickness of low‐modulus OCA to 50μm. [ABSTRACT FROM AUTHOR]

This study investigates the influence of ferrite shape modifications on the performance and noise characteristics of an induction cooktop. The goal is to optimize the air gap dimensions between ferrites and cookware, enhancing efficiency while managing noise levels. Using finite element method (FEM) simulations, we analyze the spatial distribution of magnetic forces and their harmonics. Eight ferrite shape models were examined, focusing on both outer and inner air gaps. Model #8 (reduced outer air gap) and Model #9 (reduced inner air gap) were experimentally validated. Noise measurements indicated that Model #8 reduced 120 Hz harmonic noise components, while Model #9 increased them due to enhanced excitation forces. Current measurements confirmed that Model #9 achieved higher efficiency, with RMS current reduced to 94.54% of the base model. The study reveals a trade-off between performance and noise: inner air gap reduction significantly boosts efficiency but raises noise levels, whereas outer air gap reduction offers balanced improvements. These findings provide insights for optimizing induction cooktop designs, aiming for quieter operation without compromising efficiency.

Hematite (α-Fe2O3) is widely used in sensor sensitization due to its excellent optical properties. In this study, we present a sensitivity-enhanced surface plasmon resonance alcohol sensor based on Fe2O3/Au. We describe the fabrication process of the sensor and characterize its structure. We conduct performance testing on sensors coated multiple times and use solutions with the same gradient of refractive indices as the sensing medium. Within the refractive index range of 1.3335–1.3635, the sensor that was coated twice achieved the highest sensitivity, reaching 2933.2 nm/RIU. This represents a 30.26% enhancement in sensitivity compared to a sensor with a pure gold monolayer film structure. Additionally, we demonstrated the application of this sensor in alcohol concentration detection by testing the alcohol content of common beverages, showing excellent agreement with theoretical values and highlighting the sensor’s potential in food testing.