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Embossing is a converting process in which the surface of a tissue paper sheet is changed under high pressure, allowing different functions. In this work, the authors intend to study how the embossing pressure affects the main properties of tissue paper, using a laboratory embossing system. An optimum pressure was achieved at 2.8 bar to this embossing laboratory set-up. The effect of pressure when densifying the paper sheet gives it a gain in mechanical strength but no differences in terms of liquid absorbency. The two embossing patterns present different behaviors but both evidence losses in mechanical and softness properties. On the other hand, the finite element method (FEM) does not show clear evidence of how the pressure affects the paper strength. For the deco die, it is possible to observe that the amount of yielding is slightly higher for lower pressure (2.4 bar), but this plasticity state parameter is very similar for 2.8 bar and 3.2 bar. For the micro die, FEM simulations of the manufacturing pressure do not show a considerable impact on the amount of plasticity state of the material; only for 3.2 bar, it shows a change in the pattern of the plasticity state of the paper during the embossing processes. In the end, to achieve a final product with excellent quality, it is important to make a compromise between the various properties. [ABSTRACT FROM AUTHOR]

Embossing is a functional and strategic process for creating high-quality multi-sensory tissue-paper products. Embossing modifies the sheet surface by generating hill and/or valley designs, changing the third-dimension z with a compressive die. This research work specifically concerns the impact study of the engraving finishing geometry on the final properties of tissue paper. This work led us to conclude that, even though the sheets individually present a higher hand-feel (HF) value for the straight finishing geometry, the highest softness was obtained in the two-ply prototype for the round finishing geometry. Moreover, this study confirmed that the HF value reduces with the increase of the bulk, being more accentuated for the micropattern. Relevant differences could not be seen in the spreading kinetics of the liquid droplets over time. Thus, the finishing geometry of the 3D plates did not impact the absorption kinetics on these samples. The finite element model allows us to understand the effect of the plate pattern and its finishing geometry on the paper, and the simulation results were in accordance with the experimental results, showing the same trend where patterns with a round finishing geometry marked the tissue-paper sheet more than patterns with a straight finishing did. [ABSTRACT FROM AUTHOR]

The embossing operation is one of the processes of tissue paper converting. The embossing parameters influence the final properties of tissue products, such as mechanical, softness, and bulk. In this study, the influence of the rubber hardness used against the embossing steel rolls with a pattern created by intaglio engraving was studied. Three different configurations of rubber plates stacking, each plate with different hardness, were studied. After embossing, mechanical properties, softness, and bulk were evaluated to analyze the effect of rubbers hardness on these properties. Furthermore, a Finite Element Model of the embossing operation was used that considered the same rubber plates stacking configurations used in experiments, and it was able to replicate the experimental results. This work led us to conclude that the configuration where two rubber plates with different hardness, where the rubber plate with higher hardness is in contact with the tissue paper sheet, has shown to be the best solution to obtain higher softness. These findings support the use of embossing operations rubber rolls with a low hardness internal layer and a high hardness external layer in industry. Thus, finite element models were also shown to be reliable tools to virtually test other configurations, such as, for example, three or more rubber plates with different hardness. Since embossing is one of the tissue paper transformation operations with the greatest impact on the key properties of the final product, this study allows the producer to optimize them by varying the hardness of the rubber roll, as well as its configuration. [ABSTRACT FROM AUTHOR]

Although the theoretical basis for surface acoustic wave gyroscopes (SAWGs) was first proposed in 1980, their design concepts are still under development. Nevertheless, these sensors are of a great interest in the potential market owing to their exceptional shock resistance, small size, low power consumption, and simple manufacturing process that ensures low cost. This paper aims to conscientiously investigate the ideas that have been proposed over the past decade in this area and evaluate the potential development required to bring SAWGs to market. It should be of interest for researchers in the field who might have missed some useful solutions that could be a missing piece in their own design, or for young researchers to inspire their creativity and open new research on the topic. Additionally, since some of the reviewed SAWG design concepts are based on a combination of several physical principles (for example, optical measurements), researchers from other fields may find useful solutions for incorporating surface acoustic wave techniques into their device concepts. [ABSTRACT FROM AUTHOR]

The early detection of small cracks in large metal structures is a crucial requirement for the implementation of a structural health monitoring (SHM) system with a low transducers density. This work tackles the challenging problem of the early detection of submillimeter notch-type defects with a semielliptical shape and a groove at a constant width of 100 µm and 3 mm depth in a 4.1 mm thick aluminum plate. This defect is investigated with an ultrasonic guided wave (UGW) A0 mode at 550 kHz to investigate the long range in thick metal plates. The mode selection is obtained by interdigital transducers (IDTs) designed to operate with a 5 mm central wavelength. The novel contribution is the validation of the detection by pulse-echo and pitch and catch with UGW transducers to cover a distance up to 70 cm to reduce the transducers density. The analysis of scattering from this submillimeter defect at different orientations is carried out using simulations with a Finite Element Model (FEM). The detection of the defect is obtained by comparing the scattered signals from the defect with baseline signals of the pristine laminate. Finally, the paper shows that the simulated results are in good agreement with the experimental ones, demonstrating the possible implementation in an SHM system based on the efficient propagation of an antisymmetric mode by IDTs. [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]

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]

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]

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]

In this paper, optimization of the control of an electrical machine allowing a minimization of its total losses is described. It is based on the use of an iron loss model [loss surface (LS) model] coupled to the electromagnetic finite-element simulations of the machine. The LS model is a scalar and dynamic hysteresis model developed many years ago at G2Elab and tested for iron loss prediction in several cases of electric machines. It is first characterized and improved in this paper for M330-35A SiFe sheets. Then, it is associated with a finite-element analysis to compute, in a post-processor mode, the local and global magnetic losses in the machine. For electric vehicle application, the whole torque–speed variation should be investigated. To do that, a quick response surface is constructed from a small number of simulations and the iron loss is determined. Then, a suitable optimization algorithm is developed. This approach is then illustrated by a case study and compared with classical optimization in which only the copper losses in conductors are considered. Gains of up to 50% reduction in the total losses of the machine in certain operating areas are observed. [ABSTRACT FROM AUTHOR]

• This paper presents a drained expansion solution of a cylindrical cavity with fabric change effect in the sand. • The problem is formulated as a system of first-order differential equations with the known variables. • A user-defined SANISAND model is implemented as a subroutine, which is applied to FEM simulation. Sandy soil exhibits inherently anisotropy due to its microstructure, also known as 'fabric'. However, the drastic change in fabric observed during the dilatant phase is often overlooked in current cavity expansion research. This paper presents a drained expansion solution of a cylindrical cavity with fabric change effect in the sand using a simple non-associated and anisotropic model, SANISAND. The problem is formulated as a set of first-order differential equations with the unknown variables as functions of an auxiliary coordinate, which can be solved as an initial value problem. A subroutine is implemented into the FEM simulation to verify the proposed method. Additionally, cavity expansion solutions in sand are compared with those based on state-dependent dilatancy. The anisotropic fabric of the sand is studied to investigate the impact of the initial void ratio, initial mean stress, and at-rest coefficient on the void ratio path, stress distributions and paths, and bounding surfaces. The proposed solution provides a framework for the potential use of cavity expansion in sand, considering the fabric change effect, and a benchmark for further developments and numerical calculations by using the SANISAND model. [ABSTRACT FROM AUTHOR]

Severe plastic deformation (SPD) processes offer the possibility of improving the mechanical properties of metallic materials by grain refinement. However, this great potential has so far mostly been applied on a laboratory scale or on small series. Equal-Channel Angular Pressing (ECAP) also enables to integrate the advantages in industrial processes with large output—so far, mainly for bars or thick plates. In this paper, we investigate the ECAP process for sheet metal. Preliminary investigations have shown that cracks form on the surface when aluminum AA5083 sheets are processed. To solve this problem, we determined the Johnson–Cook fracture criterion for the material and modeled the process numerically. The simulation was carried out with the superposition of a backpressure and subsequently implemented and validated experimentally. The semi-finished sheet metal products from the ECAP investigation were then mechanically characterized with microhardness measurements and tensile tests. In addition, the microstructure was investigated with Electron Back Scatter Diffraction (EBSD). Even comparatively small amounts of backpressure (10 MPa) already result in a significant suppression of the crack formation in the numerical and experimental investigations. The microhardness measurements indicate a more homogeneous strain distribution for a sufficient level of applied backpressure which enables the processing of crack-free sheets in multiple ECAP passes. As with ECAP of bulk materials, tensile tests on the processed sheets show a reduced elongation to failure (− 73%) but a significantly increased yield strength (+ 157%) compared to the initial condition of the material. Distinct substructures are found in the EBSD measurements and explain this behavior. The findings provide the basis for using ECAP on an application-oriented scale and demonstrate an advanced manufacturing method for the production of high-strength aluminum sheets. [ABSTRACT FROM AUTHOR]

The accurate modeling of wolfberry plant morphology is the basis for theoretical and simulation analyses of the wolfberry picking process. The curved shape of the fruit branches makes it challenging to model Lycium barbarum (wolfberry) plants. This paper establishes a three-dimensional model of the branches under no gravity through field measurements, and then assesses the morphology of the branches under gravity load, fruit load, and branch load using finite element simulation. An orthogonal rotation combination experiment determined the relationship between branch morphology, length, growth angle, and growth mode parameters. The p-values of the prediction model were 0.0001, 0.0067, and 0.0203, respectively. Finally, the bending shape of the actual branches was verified against the branches generated by the prediction model. The experimental results show that the prediction model accurately models the fruit-bearing branches of Lycium barbarum. This paper introduces a method to quickly predict the bending shape of fruit-bearing branches of Lycium barbarum, providing a theoretical basis for rapid modeling of the L. barbarum plant and a simulation analysis for its harvesting. [ABSTRACT FROM AUTHOR]

In the detection of small size mass loading, such as a single cell, a micro droplet or an aerosol particle, the sensors with longitudinally coupled surface acoustic wave resonator (LC-SAWR) structure can hardly avoid waveform distortions. The relative size of mass loading to the sensitive surface of the detector is the main factor affecting the response of LC-SAWR. The smaller the relative size, the worse the waveform distortion. In order to avoid influences from the mass loading's size, in this paper, a transversely coupled SAW resonator (TC-SAWR) was proposed in order to achieve high performance in sensing small size mass loadings. For the design and simulation of TC-SAWR, the two-dimensional coupling of model (2D-COM) theory and finite element method (FEM) were used in this work. In the experiment, SiO2 was deposited on the sensor's surface as a small size mass loading. The results from simulation and experiment mutually demonstrated the advantage of TC-SAWR to conquer waveform distortion in the detection of small size mass loading. [ABSTRACT FROM AUTHOR]

This paper presents the results of research aimed at assessing the effectiveness of ten selected constitutive equations for hyperelastic bodies in numerical modeling of the first compression load cycle of a polyurethane elastomer with a hardness of 90 Sh A depending on the methodology for determining the material constants in the constitutive equations. An analysis was carried out for four variants for determining the constants in the constitutive equations. In three variants, the material constants were determined on the basis of a single material test, i.e., the most popular and available in engineering practice, the uniaxial tensile test (variant I), the biaxial tensile test (variant II) and the tensile test in a plane strain (variant III). In variant IV, the constants in the constitutive equations were determined on the basis of all three above material tests. The accuracy of the obtained results was verified experimentally. It has been shown that, in the case of variant I, the modeling results depend to the greatest extent on the type of constitutive equation used. Therefore, in this case it is very important to choose the right equation. Taking into account all the investigated constitutive equations, the second variant for determining the material constants turned out to be the most advantageous. [ABSTRACT FROM AUTHOR]

One of the most dominant manufacturing methods in the production of electromechanical devices from sheet metal is punching. In punching, the material undergoes plastic deformation and finally fracture. Punching of an electrical steel sheet causes plastic deformation on the edges of the part, which affects the magnetic properties of the material, i.e., increases iron losses in the material, which in turn has a negative effect on the performance of the electromagnetic devices in the final product. Therefore, punching-induced iron losses decrease the energy efficiency of the device. FEM simulations of punching have shown significantly increased plastic deformation on the workpiece edges with increasing tool wear. In order to identify the critical tool wear, after which the iron losses have increased beyond acceptable limits, the simulation results must be verified with experimental methods. The acceptable limits are pushed further in the standards by the International Electrotechnical Commission (IEC). The new standard (IEC TS 60034-30-2:2016) has much stricter limits regarding the energy efficiency of electromechanical machines, with an IE5 class efficiency that exceeds the previous IE4 class (IEC 60034-30-1:2014) requirements by 30%. The simulations are done using Scientific Forming Technologies Corporation Deform, a finite element software for material processing simulations. The electrical steel used is M400-50A, and the tool material is Vanadis 23, a powder-based high-speed steel. Vanadis 23 is a high alloyed powder metallurgical high-speed steel with a high abrasive wear resistance and a high compressive strength. It is suitable for cold work processing like punching. In the existing literature, FEM simulations and experimental methods have been incorporated for investigating the edge deformation properties of sheared surfaces, but there is a research gap in verifying the simulation results with the experimental methods. In this paper, FEM simulation of the punching process is verified using an electrical steel sheet from real production environment and measuring the deformation of the edges using microhardness measurements. The simulations show high plastic deformation 50 μm into the workpiece edge, a result that is shown to be in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The laser shock adhesive-clinching (LSAC) is an original material joining technique that combines the advantages of clinch-bonded hybrid joining and laser shock clinching, in which two metal foils are bonded by adhesive and clinched by laser shock simultaneously. In this paper, the LSAC joints are manufactured by 1060 Al foils, Henkel EP 5055 adhesive, and perforated 304 stainless steel sheets. Through experiments and FEM simulations, the LSAC process and the deformation of LSAC joints under shear loads are analyzed, and the effect of adhesive on LSAC joint manufacturing is investigated. The results show that bulging is the dominant deformation behavior during LASC, and the cured adhesive with thin thickness is beneficial to the subsequent clinching process. The shear strength of the LSAC joint is greatly enhanced compared to the pure clinched and pure bonded joints. The shear failure process of the LSAC joint is adhesive degumming first, then the interlock separating. [ABSTRACT FROM AUTHOR]

This paper presents the results of field tests of a designed A-frame blade pile system that is used for resisting lateral wind load action in a solar farm project. The developed system contains an A-frame and two blade piles connected by bolts. The design of A-frame leg-to-ground angle is provided, and a cyclic load test was performed to research the ultimate failure criteria. By data interpretation after testing, it is found that two blade piles have different loading capacities. The reason is that these two piles' mechanical behaviour is different. In detail, one pile is subjected to the "pull out" action, whereas the other pile is subjected to the "push in" effect. Further, the mechanical behaviour of soil is found in this research. The FEM result provided very close behaviour of soil and A-frame blade pile system. Based on the onsite test data and FEM data analysis, the FEM model can provide conservative results. Lastly, the ultimate capacity of this newly developed A-frame blade pile system is defined. [ABSTRACT FROM AUTHOR]

For this paper, the possibility of using grain-oriented electric steel for the stator lamination in a double rotor fractional-slot concentrated-wound permanent magnet synchronous motor it was studied using FEM simulations. The results were compared with the ones of the non-oriented electric steel machine having two different stator lamination topologies. The purpose of this study was to estimate the influence of the stator yoke discharge for the proposed structure and to check the possibility of compensating some of its negative effects by using grain-oriented electric steel for stator lamination. The proposed solution gives the advantage of a modular construction of the stator lamination which simplifies the fabrication technology and reduces the production costs, at the same time, without major impact over the machines performances. [ABSTRACT FROM AUTHOR]

This paper aims to develop a new forming technique to manufacture a long semihollow stepped part. Traditionally, hot backward extrusion is used, but this technique is not suitable because it requires a very high forming load to act on the die and punch, especially at the contact between the punch and workpiece. As a result, the service life of the punch is very low. Therefore, a new technique to overcome this problem is needed. A combined bulging–piercing technique was proposed and developed in this research. The main concept of this technique is to bulge the part by upsetting the workpiece between the punch and counterpunch to generate high frictional contact pressure, which will help to restrain the material from sliding down into the die cavity during the piercing step. In other words, this technique utilizes frictional force at the die–workpiece interface to reduce the forming load of the punch. Finite element modeling was employed to investigate and determine a suitable level of the bulging which can reduce the forming load without generating any significantly high force to the counterpunch. Only experiments with the minimum forming load were selected and implemented to validate this concept because other conditions with high load will risk damaging the punch and machine press of the product line. The results show that this technique can reduce the forming load by almost 40% and also control a good concentricity of the part and reduce the wall thickness variation. [ABSTRACT FROM AUTHOR]

In this paper, some practical issues related to the manufacturing, and design criteria related to the application in devices of a hybrid silver grid/poly (3,4-ethylenedioxythiophene) semi-transparent electrode are discussed. The electrodes are fabricated by gravure printing and screen printing. Experiments showed that defects in the printed grid due to imperfect ink transfer from the gravure roll to the substrate are detrimental to electrode performance. Various parameters like gravure cell design, printing speed, or particle size of the ink were investigated to minimize the fraction of defects and to obtain highly conductive grids. It will be demonstrated that overprinting of the lines is a feasible strategy to minimize the number of defects without noticeably broadening the lines. While a defect-free grid is prerequisite for such a hybrid device, for applications even stronger design criteria hold. That is addressed in the second part of the paper, where the electrical properties of the printed grids are simulated. With two exemplary device architectures, namely an organic light-emitting diode (OLED) and an organic photovoltaic cell, artificial load layers are integrated into the device structure, and potential maps are calculated. The examples show how simulations can be deployed to design and optimize grid electrodes for a specific application. [ABSTRACT FROM AUTHOR]

Grain loss in the harvesting process of combine harvesters not only causes economic losses to farmers but also affects the soil environment because of the lost grain covering the soil, influencing crop growth in the next season. Grain sieve loss-monitoring sensors represent an important accessory in combine harvesters, as they can not only provide current grain loss levels for the operator to adopt a rational action in time but also serve as an important performance signal for the control system. To reflect the rice grain sieve loss level of combine harvesters in real time, an indirect grain sieve loss-monitoring system is proposed in this paper. First, the grain collision rise time was obtained by the finite element method (FEM), and the parameters of the grain loss sensor signal processing circuit were determined accordingly to upgrade the monitoring accuracy. Then, grain loss distribution behind the cleaning shoe was analyzed in detail under different working parameters. Grain loss distribution functions at the end of the sieve and a monitoring mathematical model with relevant variables were established based on the laboratory experiment results. Finally, calibration experiments were carried out to verify the measurement accuracy of the sensor on a cleaning test bench, with an obtained relative monitoring error ≤6.41 % under different working conditions. [ABSTRACT FROM AUTHOR]

The filling stage is a critical phenomenon in sand casting for making reliable castings. Latest research has demonstrated that for most liquid engineering alloys, the critical meniscus velocity of the melt at the ingate is in the range of 0.4–0.6 m s−1. The work described in this research paper is to use neural network (NN) technology to propose digital twin approach for gating system design that allow to understand and model its performances faster and more reliable than traditional methods. This approach was applied in the case of sand casting of liquid aluminum alloy (EN AC-44200). The approach is based first on a digital representation of filling process to perform the melt flow simulations using a combination of the gating system design parameters, selected as a training cases from Taguchi orthogonal array (OA). The second step of the approach is the data capture of functional gating design system to train up the feed-forward back-propagation NN model. The validation of the well-trained NN model is assessed by interrogating predicted ingate velocity to it and making reliable predictions with high accuracy. The claim is that such digital twin approach is an effective solution to recognize the functional design parameters from the entire filling systems used during casting process. [ABSTRACT FROM AUTHOR]

The acoustic emission (AE) technique has become a well-established method of monitoring structural health over recent years. The sensing and analysis of elastic AE waves, which have involved piezoelectric wafer active sensors (PWAS) and time domain and frequency domain analysis, has proven to be effective in yielding fatigue crack-related information. However, not much research has been performed regarding (i) the correlation between the fatigue crack length and AE signal signatures and (ii) artificial intelligence (AI) methodologies to automate the AE waveform analysis. In this paper, this crack length correlation is investigated along with the development of a novel AE signal analysis technique via AI. A finite element model (FEM) study was first performed to understand the effects of fatigue crack length on the resulting AE waveforms and a fatigue experiment was performed to capture experimental AE waveforms. Finally, this database of experimental AE waveforms was used with a convolutional neural network to build a system capable of performing automated classification and prediction of the length of a fatigue crack that excited respective AE signals. AE signals captured during a fatigue crack growth experiment were found to match closely with the FEM simulations. This novel AI system proved to be effective at predicting the crack length of an AE signal at an accuracy of 98.4%. This novel AI-enabled AE signal analysis technique will provide a crucial step forward in the development of a comprehensive structural health monitoring (SHM) system. [ABSTRACT FROM AUTHOR]

A novel prefabricated curling rink supported by steel frame and precast concrete blocks has been tested by the 2019 China Youth Curling Open, and that will be responsible for the Beijing Winter Olympics and Winter Paralympics curling competitions in 2022. Due to quite limited researches on the mechanical properties of this professional curling venue, the dynamic behavior of the prefabricated rink under human activities are not well understood. In particular, people and curling stones are potentially more susceptible to the ice vibrations when compared to the traditional curling rink constructed on rammed foundation. Small ice rink vibrations caused by the human locomotion load can make athletes feel uncomfortable, which could affect competition experience, techniques, and skills of the occupancies. At the same time, it can also result in a slightly change of the curling stone trajectories, which ultimately caused the athletes to adopt an erroneous strategy. In order to get a further understanding of the above problems, this paper conducts a series of performance studies based on the 3D finite element model built in ABAQUS and the measured dynamic loads. In this context, it includes the research of on-site measurement of dynamic loads caused by different types of human locomotion on ice sheet, which can provide a reference to the dynamic performance design of prefabricated curling rink supported by similar structural systems. Moreover, the time and amplitude parameters of the footfall forces are extracted to analyze and be compared with the human induced loads results from the existing research, generally obtained on the concrete surface. Then, on the base of the finite element model verified by experiment, the experimental achieved loads are applied for the dynamic analysis to study the vibration acceleration and velocity response of ice sheet. Finally, the vibration response results, including peak acceleration (PA), vibration dose value (VDV), root mean square acceleration (RMS), as well as root mean square velocity were evaluated according to the regulations proposed by the International Olympic Committee and the vibration evaluation standards suggested by AISC design guide, ISO guideline, and VC curves. The analysis results indicate that innovation prefabricated curling ice rink supported by steel-concrete composite floors can meet the requirements of the event and has the prospect of promotion and application. [ABSTRACT FROM AUTHOR]

In recent years, the interest in monitoring the operating conditions of freight wagons has grown significantly to improve the safety of railway vehicles. The railway research group of the Politecnico di Torino has been working for years on the development of solutions to effectively monitor the operating conditions of passenger and freight rail vehicles. As part of the national Cluster ITS Italy 2020 project funded by Italian ministry of education, university and research (MIUR), the Politecnico di Torino has collected a considerable amount of data thanks to the wired and wireless prototypes developed. The data obtained are used in this paper for the validation and calibration of a finite element (FE) model that simulates the temperature variation of a cast iron brake block due to braking operations of an intermodal freight wagon. The developed model can be a useful tool to predict the temperature at the wheel–shoe interface as a function of the current operating conditions since a direct measurement is not easy to perform. [ABSTRACT FROM AUTHOR]

In this paper we present a multidisciplinary modeling of a MEMS-based electrodynamic microsensor, when an additional vertical offset is defined, aiming acoustic applications field. The principle is based on the use of two planar inductors, fixed outer and suspended inner. When a DC current is made to flow through the outer inductor, a magnetic field is produced within the suspended inner one, located on a membrane top. In our modeling, the magnetic field curve, as a function of the vertical fluctuation magnitude, shows that the radial component was maximum and stationary for a specific vertical location. We demonstrate in this paper that the dynamic response of the electrodynamic microsensor was very appropriate for acting as a microphone when the membrane is shifted to a certain vertical position, which represents an improvement of the microsensor's basic design. Thus, a proposed technological method to ensure this offset of the inner inductor, by using wafer bonding method, is discussed. On this basis, the mechanical and electrical modeling for the new microphone design was performed using both analytic and Finite Element Method. Firstly, the resonance frequency was set around 1.6 kHz, in the middle of the acoustic band (20 Hz – 20 kHz), then the optimal location of the inner average spiral was evaluated to be around 200µm away from the diaphragm edge. The overall dynamic sensitivity was evaluated by coupling the lumped elements from different domains interfering during the microphone function. Dynamic sensitivity was found to be 6.3 μV/Pa when using 100 µm for both gap and vertical offset. In conclusion, a bandwidth of 37.6 Hz to 26.5 kHz has been found which is wider compared to some conventional microphones. [ABSTRACT FROM AUTHOR]

Two-point incremental forming (TPIF) shows higher forming limits than single-point incremental forming (SPIF) especially for producing complex industrial functional components. However, unexpected failure still occurs occasionally under certain forming conditions in TPIF. In this paper, the applicability of six damage models for failure prediction in TPIF is evaluated. The procedure of damage parameter calibration and finite element modelling are presented. The predicted failure depth and location with these damage models are evaluated under different loading conditions. Furthermore, the stress and strain and damage evolution in TPIF are provided and discussed in detail. It is concluded that the failure location and depth can be predicted more accurately by the Ayada model than others in this work. It is noted that once double-sided contact occurs in TPIF, it reduces the variation of triaxiality through the thickness, altering the accumulation of damage. [ABSTRACT FROM AUTHOR]

In glass compression molding, most current modeling approaches of temperature‐dependent viscoelastic behavior of glass materials are restricted to thermo‐rheologically simple assumption. This research conducts a detailed study and demonstrates that this assumption, however, is not adequate for glass molding simulations over a wide range of molding temperatures. In this paper, we introduce a new method that eliminates the prerequisite of relaxation functions and shift factors for modeling of the thermo‐viscoelastic material behavior. More specifically, the temperature effect is directly incorporated into each parameter of the mechanical model. The mechanical model parameters are derived from creep displacements using uniaxial compression experiments. Validations of the proposed method are conducted for three different glass categories, including borosilicate, aluminosilicate, and chalcogenide glasses. Excellent agreement between the creep experiments and simulation results is found in all glasses over long pressing time up to 900 seconds and a large temperature range that corresponds to the glass viscosity of log (η) = 9.5 – 6.8 Pas. The method eventually promises an enhancement of the glass molding simulation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Resin transfer molding (RTM) technologies are widely used in automotive, marine, and aerospace applications. The need to evaluate the impact of design and production critical choices, also in terms of final costs, leads to the wider use of numerical simulation in the preliminary phase of component development. The main issue for accurate RTM analysis is the reliable characterization of the involved materials. The aim of this paper is to present a validated methodology for material characterization to be implemented and introduce data elaboration in the ESI PAM-RTM software. Experimental campaigns for reinforcement permeabilities and resin viscosity measurement are presented and discussed. Finally, the obtained data are implemented in the software and then compared to experimental results in order to validate the described methodology. [ABSTRACT FROM AUTHOR]

Finite element simulations are being more and more applied when studying the crash-worthiness of vehicles during impact. This paper deals with setting up such a simulation and discusses several ways to simplify and verify a simulated crash. For this purpose, a notch impact-testing machine will be released from a certain angle and crash into a model constructed with three different wall thicknesses. The plastic and elastic deformation is measured in the front of the model and is then used for validation of the simulation. In the end, the simulation was found to be in good agreement with the real crash data. [ABSTRACT FROM AUTHOR]

Pre-stress hardening grinding (PSHG) is a complex process that combines pre-stress grinding and grinding hardening. Pre-stress, as input stress, has been working throughout the grinding process. Since the grinding heat generates on the surface of material, unloading the pre-stress at different time nodes will affect the phase change after the grinding process. In this paper, the effect between pre-stress unloading time and the grinding hardening is further studied. In order to study the effect of pre-stress unloading time, experiment and simulation are used for analysis and to optimize grinding hardening layer in the PSHG process. After the PSHG experiment, the microstructure of the grinding-hardened surface is observed and investigated by scanning electron microscopy (SEM). And the SEM images are binarized to obtain the martensite content on the hardened surface. It is showed that as the pre-stressed unloading time increases, the martensite content increases. Then, a simulation model is established based on the heat conduction equation, initial boundary conditions, and latent heat of phase change. According to the simulation results, three time nodes are selected to study the unloading pre-stress. The pre-stress unloading time affects the mechanical thermal stress of the material surface layer, but has little effect on the inner layer. In the simulation, the influence of the pre-stress unloading time on the mechanical-thermal stress of the surface is compared. Finally, the effects of pre-stress unloading time on the phase transition and phase transition stress are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Theoretical formulas describing wave propagation in multilayer are derived. • The attenuation is dominated by physical properties of the interface and stride. • The attenuation is regulated by the ratio of single-layer thickness to the FWHM. • A novel dynamic design method for coatings is presented. 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. [ABSTRACT FROM AUTHOR]

Shock wave boundary/layer interactions (SWBLIs) are critical in high-speed aerodynamic flows, particularly within supersonic regimes, where unsteady dynamics can induce structural fatigue and degrade vehicle performance. Conventional measurement techniques, such as pressure-sensitive paint (PSP), face limitations in frequency response, calibration complexity, and intrusive instrumentation. Similarly, MEMS-based sensors, like Kulite® sensors, present challenges in terms of intrusiveness, cost, and integration complexity. This study presents a flexible, lightweight polyvinylidene fluoride (PVDF) piezoelectric sensor array designed for high-resolution wall-pressure measurements in SWBLI research. The primary objective is to optimize low-frequency pressure fluctuation detection, addressing SWBLI's need for accurate, real-time measurements of low-frequency unsteadiness. Fabricated using a double-sided screen-printing technique, this sensor array is low-cost, flexible, and provides stable, high-sensitivity data. Finite Element Method (FEM) simulations indicate that the sensor structure also has potential for high-frequency responses, behaving as a high-pass filter with minimal signal attenuation up to 300 kHz, although the current study's experimental testing is focused on low-frequency calibration and validation. A custom low-frequency sound pressure setup was used to calibrate the PVDF sensor array, ensuring uniform pressure distribution across sensor elements. Wind tunnel tests at Mach 2 verified the PVDF sensor's ability to capture pressure fluctuations and unsteady behaviors consistent with those recorded by Kulite sensors. The findings suggest that PVDF sensors are promising alternatives for capturing low-frequency disturbances and intricate flow structures in advanced aerodynamic research, with high-frequency performance to be further explored in future work. [ABSTRACT FROM AUTHOR]

The grind-hardening process aims to increase the surface hardness of the material through the dual action of the mechanical and thermal load. A novel approach to model the process and predict the hardness penetration depth was developed based exclusively on the prediction of austenite-martensite transformation. A combined micro and macro scale approach was implemented to forecast the temperature reached in the surface starting from the action of a single grain and using its specific cutting power to design a moving heat source representing the interaction between the grinding wheel and the material. The martensitic transformation temperature considered in this paper takes into consideration the fast heat cycle typical of this process. In order to validate the model, tangential surface grinding tests were performed on 42CrMo4 and microstructural analysis with micro-hardness measurements were performed. This research presents a first step in developing a grinding process simulation that includes multi-grain grinding, real grain geometries, binder effect, and real workpiece-grinding wheel kinematics. [ABSTRACT FROM AUTHOR]

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Friction behavior in a sliding contact is strongly influenced by the surface topography of the bodies in contact. This also applies to friction clutches. Even small differences in surface topography may cause significant differences in friction behavior. Thus, it is important to be able to characterize the micro-contact of the rough sliding surfaces, which are, in the case of a clutch, steel plate and friction material. One important measure for the characterization of the micro-contact is the real area of contact. Another important aspect is the contact pattern. The article introduces a method to implement a FEM (Finite Element Method) model from real surface measurements. Real surface topography of the friction pairing is considered. The simulation method is applied to different friction pairings and operating conditions. Computational results with rough and smooth steel plates, new and run-in friction linings, and different nominal surface pressure verify the model. In addition, the results on real area of contact between a steel and a friction plate are compared with published values. [ABSTRACT FROM AUTHOR]

This article presents a research study involving different simulations of crash tests by means of the finite element explicit dynamic software Ansys LS-Dyna to determine the roadworthiness of a fully composite chassis lightweight solar vehicle and its conformity to the World Solar Challenge (WSC) regulations. Furthermore, the paper describes the results of crash test simulations in conditions comparable with those of the standard homologation test, with an initial velocity of 15.5 m/s against a rigid barrier considering overlaps of 50% and 100%. The velocity measured at the base of the seat was later used in a sled test with a dummy to calculate the Head Injury Criterion (HIC), a number proportional to the probability of head injury caused by the impact. The values remained within the threshold of acceptability with overlap at 50% but exceeded the limit with the 100% overlap. With no load limiter implemented in the model, the seatbelt caused contact forces with the chest up to 14 kN against 6 kN of the typical load limiter used in road cars to limit damage to ribs and internal organs. Finally, the possibility of improving the front crash box was investigated by changing the crash box's planar sandwich structure with corrugated ones and layup without foam between the carbon layers. Various values of semi-amplitudes (A) of the sinusoidal profile have been tested. With a value of A of 6 mm, the capacity to absorb energy from an impact at 9 m/s was close to the original configuration. [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]

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]

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]

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]

The pre-stressed hardening grinding (PSHG) combines with the advantages of pre-stressed grinding and grinding hardening. In order to study the characteristic of PSHG, especially its residual stress within a hardened layer after PSHG, the PSHG experiment was carried on. Combining with theory and experiment results, the variation and its mechanism of residual stress were studied. The paper shows the PSHG can obtain a hardened layer with controllable residual stress after the process. The residual stress decreases with the increasing of feeding speed and grinding depth. When the grinding depth is small, the tensile residual stress decreases with the increasing of pre-stress. And when the grinding depth is large, the compressive residual stress decreases first and then increases with the increase of pre-stress because of the comprehensive effect of heat and phase transformation. Then, a finite element method (FEM) simulation was performed to study the variation of thermal stress in a hardened layer after PSHG process. Distribution and variation of thermal stress were obtained. In the end, according to the relationship between residual stress and thermal stress, the distribution and variation mechanisms of phase transformation stress were obtained and studied. They vary along with the level of phase transformation. The compressive phase transformation stress increases with the increasing of grinding depth. And due to the pre-stress's influence on the phase transformation, it decreases first and then increases with the increase of pre-stress. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical trimming process for hot stamped ultra-high strength parts was studied, in which the properties of fracture profile were analyzed and the effects of process parameters were evaluated. The research was carried out by FEM simulation with comparison and chosen of damage models, where the critical damage values were obtained through an iterative “predictor-corrector approach”. In addition, an experimental trimming tool was designed to study the effects of variable process parameters and verify the simulation results. By comparison, it was found that the Oyane damage model agreed with the experimental results better than others. The simulation and experimental results showed that the quality of trimmed hot stamped surface was poor with not straight profile and small burnish zone, but it can be improved by choosing proper trimming angle and blade radius. Such phenomena were discussed and explained in terms of stress state. Tensile stress accelerates the damage value while compress stress inhibits it. This paper helps to better understand the mechanical properties of hot stamped ultra-high strength steel. [ABSTRACT FROM AUTHOR]

This paper summarizes the research work aimed to elaborate a new plating method for axisymmetric metallic parts by precision cold forming on rotary swaging principle and, on this basis, to develop an environmentally friendly technology for net-shape plating. The new technology is intended to create parts with the basic structure made from cheap materials with high fatigue strength, on which, in areas where they require different characteristics (low friction coefficients, greater hardness, greater corrosion resistance, etc.), a layer of more expensive materials that provide these features is applied. At first, the new method of plating through rotary swaging was developed and the net-shape plating technology was preliminarily designed. Then, the experimental technology was analyzed and optimized employing process simulation by finite element method (FEM). A nonlinear finite element analysis (FEA) package, MSC.Marc/Mentat, was used. The full 3D FEM model established in this study eliminates some of the limitations encountered in the previous works using the real movement curve for dies and accurate boundary conditions. The model running tests indicate that the relative positioning between base workpiece and coating tube is of crucial importance in this application. Finally, practical experiments were carried out, the results been used for validation of the 3D simulation model, for physical-mechanical characterization of the joining between base part and coating layer and for technology design finalization. A good agreement between experiments and simulation was found. Also, the experiments indicate that the joint is more tightened when the inside workpiece has a yield strength greater than the outer workpiece. [ABSTRACT FROM AUTHOR]