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The Proton Exchange Membrane Fuel Cell (PEMFC) performances are strongly impacted by the compression of the Gas Diffusion Layer (GDL). Despite its fibrous microstructure, this material is usually considered as a continuous medium and characterized with uniform loading. However, the GDL is subjected to a heterogeneous compression onto rib/channel patterns in the fuel cell assembly. In the present study, a complex behavior of the GDL response is experimentally revealed when the material is loaded with a rib/channel pattern, compared to uniform compression. The tests are simulated by finite element modeling using a classical strain-dependent elastic law, using parameters fitted from uniform compression experiments. It is shown that the numerical results do not reproduce the effect of pattern observed experimentally. Hypotheses to interpret these results involve mechanisms at the fiber microscale including fiber fracture, cross-link breakage and fiber rearrangement, which are exacerbated by larger material deformation caused by the heterogeneous loading. • Unexpected impact of rib/channel patterns on GDL compression. • Experimental investigation of the effect of rib/channel width on GDL deformation. • Numerical study with classical model unable to reproduce experimental results. • Interpretations based on mechanisms at the fiber microscale. [ABSTRACT FROM AUTHOR]

The dynamic mechanical behavior and cushioning performance of honeycomb sandwich panels, which are extensively employed in product cushioning packaging due to their exceptional energy absorption capabilities, were examined using a combination of experimental and numerical methods. Several factors, such as maximum acceleration–static stress, cushioning coefficient–static stress, and other curves, were analyzed under various impact conditions. The simulated stress–strain, deformation modes, cushioning coefficients, and other parameters demonstrate consistency with the experimental results. The acceleration, maximum compression, and cushioning coefficient obtained from the experiment and simulation calculation were 30.68 g, 15.44 mm, and 2.65, and 31.96 g, 14.91 mm, and 2.79, respectively. The results indicate that all error values were less than 5%, confirming the precision and reliability of the model. Furthermore, the model was utilized to simulate and predict the cushioning performance of honeycomb sandwich panels with different cell structures and paper thicknesses. These results provide a solid basis for enhancing the design of subsequent honeycomb element structures. [ABSTRACT FROM AUTHOR]

Optical eigenstates with a high quality (Q) factor provide substantial advantages for a broad spectrum of optical devices, particularly those demanding strong light–matter interactions. Recently, it has been demonstrated that ultrahigh- Q resonances can be realized in planar photonic structures by merging multiple bound states in the continuum (BICs) in the momentum space. Photonic lattices with thin-film geometry are known to support abundant TE-polarized and TM-polarized BICs. While prior research has explored the merging of TE-polarized BICs, this paper presents analytical and numerical results concerning the merging of TM-polarized BICs in laterally periodic one-dimensional photonic lattices. As the thickness of photonic lattices increases, TM-polarized accidental BICs descend along the dispersion curves and eventually merge at the upper edge of the second stop band. Employing coupled-mode analysis, we calculate the analytical merging thickness at which multiple TM-polarized BICs come together at the second-order Γ point. We confirm the merging of TM-polarized BICs through finite-element method simulations. Our results can be beneficial for achieving ultrahigh- Q resonances through the merging of BICs. [ABSTRACT FROM AUTHOR]

Electroporation is a complex, iterative, and nonlinear phenomenon often studied through numerical simulations. In recent years, simulations of tissue electroporation have been conducted with static models. However, the results of a static model simulation are restricted to a fixed protocol signature of the pulsed electric field. In this paper, we describe a novel dynamic model of tissue electroporation that also accounts for tissue dispersion and temperature to allow time-domain simulations. We have implemented the biological dispersion of potato tubers and thermal analysis in a commercial finite-element method software. A cell electroporation model was adapted to account for the increase in tissue conductivity. The model yielded 12 parameters divided into three dynamic states of electroporation. The thermal analysis describes the dependence of tissue conductivity on temperature. The model parameters were evaluated using experiments with vegetal tissue (Solanum tuberosum) under electrochemotherapy protocols. The proposed model can accurately predict the conductivity of tissue under electroporation from 100 to 1000 V/cm. A negligible thermal effect was observed at 1000 V/cm, with a temperature increase of 0.89 ° C. We believe that the proposed model is suitable to describe the electroporation at the tissue level and provides a hint of the effects on the cell membrane. [ABSTRACT FROM AUTHOR]

An epiretinal membrane (ERM) is a fibrocellular proliferation on the inner surface of the retina causing blurred and distorted central vision. Surgery is the only effective method for ERM removal. This paper investigated the mechanical properties of ERM peeling using the finite element (FE) method. A FE model of ERM formation on the retina surface was constructed. The failure criterion was applied to the attachment pegs to represent the adhesive force between the ERM and retina. The simulation results were consistent with the experimental data in published research. The maximum peeling force was 4.1 mN at a peeling velocity of 2 mm/s and an angle of 30°. The peeling force was minimum at the peeling angle of 45° and increased with the increase in peeling velocity and Young's modulus of the membrane. The outcome of this paper can improve the safety and efficiency of ERM removal. [ABSTRACT FROM AUTHOR]

The concept of digital twins in bridge engineering is still vague and even confused with the Bridge Information Model (BrIM). Therefore, this study provides a detailed review of 42 papers related to digital twins in bridge engineering, focusing on a proper definition, key features and creation techniques for bridge digital twin (BDT). The paper also compares BDT and BrIM from the perspectives of their elements, features, fidelity, services provided, and degree of development. The applications of BDT at different life cycle stages are identified, and the related technologies are analyzed in detail. The results show that the research clusters of BDT are divided into geometric model generation, finite element model updating, and management and are focused on the operation and maintenance phase while lacking attention in the design and construction phase. Besides, a reference framework of BDT based on the life cycle of bridges is proposed, and directions for future research are suggested. [ABSTRACT FROM AUTHOR]

Based on the perspective of flight technology and flight safety, the unsaturated clayey foundation soil of a high plateau airport in the mountainous area of southwest China is taken as the research object, and the calculation method of the composite modulus of CFG pile composite foundation with the soil between the piles as the unsaturated soil is established according to the relevant characteristics of unsaturated soil, and the calculation method of the composite foundation's settlement is carried out on the basis of this method. At the same time, Plaxis finite element analysis software is used to model the actual project and numerically analyze the settlement characteristics of the composite foundation. Finally, the calculation results of the two methods are compared and studied with the actual settlement monitoring values on site. The study shows that: 1) the theoretical analysis method is able to consider the effects of pile length, pile modulus, and matrix suction in unsaturated soil of rigid piles on the composite modulus, which is more in line with the reality than the conventional composite modulus method that does not consider the unsaturated nature of the soil between the piles; 2) the resultant values computed by the theoretical and numerical analysis methods recommended in this paper are both smaller than those measured at the site but the difference is within the range of 10%, so that in the actual plateau of the High Plains airports can choose the two analysis methods recommended in this paper to conduct related research. [ABSTRACT FROM AUTHOR]

The wear of backup rolls will have a great impact on the quality of the shape of hot rolled strip sheet. In order to overcome the limitations of the finite element method (FEM) in calculating backup roll wear in terms of efficiency and accuracy, this paper proposes a tandem FEM + ML hybrid model to optimise the predictive effect of the finite element method (FEM) on backup roll wear. Firstly, a backup roll wear model based on FEM is established. Secondly, in order to select the optimal machine learning (ML) algorithm as the finite element error compensation model, three types of finite element error compensation models were established based on the random forest (RF) algorithm, the radial basis function (RBF) neural network algorithm, and the particle swarm optimisation support vector machine (PSO-SVM) algorithm. Finally, the three types of finite element error compensation models were connected in series with the FEM model to compare the prediction performance of the three types of FEM + ML models on backup roll wear. The numerical experimental results show that the FEM + PSO-SVM model can better predict the wear of the backup roll, and the PSO-SVM algorithm is the most suitable for building the finite element error compensation model. It is proved that the FEM + ML model proposed in this paper can effectively improve the accuracy and computational efficiency of the FEM model for predicting backup roll wear without adding microelements. In addition, among the hot rolling parameters, the rolling force has the greatest influence on the backup roll wear, and excessive rolling force for a single pass should be avoided to slow down the backup roll wear. [ABSTRACT FROM AUTHOR]

In this paper, a ground-based experimental system for solar array active vibration suppression has been established. Firstly, in order to establish an accurate model of the solar array, the solar array is regarded as a flexible cantilevered thin plate, and the corresponding dynamical equations are derived using the absolute nodal coordinate method. In addition, in this paper, the more advanced MFC piezoelectric patch is used instead of the traditional PZT piezoelectric ceramic patch. The electromechanical coupling finite element model of the P1-type MFC patch is established and substituted into the kinetic equation of the solar array. Finally, the accuracy of the electromechanical coupling modeling and the control effect of active vibration suppression were verified using the PID control. A set of experimental frameworks for evaluating the active vibration suppression effect, including the free vibration test, sinusoidal perturbation test, and white noise perturbation test, as well as the analysis strategy of the test data, are established. [ABSTRACT FROM AUTHOR]

This paper presents a forced vibration analysis of open doubly curved sandwich panels subjected to a moving constant force. In this paper, the effect of softness of the core is considered by implementing a semi-layerwise theory. To this aim, the first-order shear deformation theory is adopted for the face sheets and a higher-order theory which was obtained based on 3D elasticity theory is considered for the core. The presented formulation is general and as the deepness parameter is accounted in the strain–displacement relations, the formulation can be used for a wide range of deep as well as shallow doubly curved shells. To obtain the dynamic response of the system, the finite element method (FEM) along with the Newmark method is used. The proposed element is a higher-order one with nine nodes and each node has fifteen degrees of freedom. The effect of various parameters such as length-to-thickness ratio, in-plane aspect ratio, boundary conditions, lamination scheme, and fiber orientation angles on the dynamic response of the structure is examined. Additionally, the critical velocity of the force at which the structure experiences maximum dynamic deflection is obtained in each case. The results show that as the length-to-thickness ratio of the structure increases, the dynamic magnification factor curve increases with respect to non-dimensional velocity. This study provides insights into the dynamic behavior of doubly curved sandwich panels with soft cores and can aid in the design of such structures for specific applications. The results of this study can also serve as a benchmark for future studies on the forced vibration behavior of doubly curved sandwich panels. [ABSTRACT FROM AUTHOR]

This paper introduces a novel index for static eccentricity (SE) fault diagnosis in synchronous reluctance motors (SynRMs). Although SynRMs with rotor barriers under SE have been modeled in a few papers, any indices for the fault detection have not yet been reported. The proposed index is a specific frequency pattern in the motor current, which can also determine the fault severity. A novel analytical magnetic field investigation is applied to ascertain the proposed index. An accurate nonlinear numerical method is proposed for the motor inductances calculation. The model considers the rotor flux barriers, magnetic saturation, and the stator slots effect. The air gap flux density and the motor current are then achieved. The fast Fourier transform is exploited as a signal-processing tool to calculate motor current spectra. Then, a two-dimension time-stepping finite element method is used to attest of the proposed numerical model. Effectiveness of the proposed index is verified by simulation and experimental tests. [ABSTRACT FROM AUTHOR]

This paper has proposed an efficient analysis method to calculate interface stress intensity factors (SIFs) based on a proportional stress field of a reference problem whose exact solution is available. In the previous proportional methods, the same crack length and the same element size were applied to both reference and unknown problems so that the same FEM error can be produced. Therefore, when analyzing many unknown problems, the conventional method needs to analyze many reference problems at the same time. Since this approach is time-consuming, this paper considers how to calculate many crack lengths efficiently by using only one single reference solution modeling. For this purpose, several general relations of SIFs are derived for the unknown and the reference problems when both crack length and element size are different. To analyze many unknown problems accurately by using a single reference solution modeling, how to choose the most suitable element dimension of the reference model is clarified. The proposed method is especially useful for crack propagation analysis. [ABSTRACT FROM AUTHOR]

Kalman filter has emerged as a powerful tool for unbalance identification in rotating machinery. Recently, the augmented Kalman filter combined with the finite element model has grown up and projects its potential for complex rotor systems. This paper investigates the application of the augmented Kalman filter (AKF) to a practical turbofan engine. The current study reveals that using steady-state responses as measurements can cause fluctuation in the estimated results, even divergence for some cases, while the available signals in practice are steady-state responses generally. To the authors' knowledge, this practical problem is revealed for the first time. To address the problem, the convergence criterion is employed to improve the AKF and formulates the adaptive fading augmented Kalman filter (AFAKF) proposed in this paper. Results indicate that the increase of the amplification factor, the insufficient measurement points, and the complexity of the dynamic model can all lead to the deterioration of the estimated unbalance. The proposed AFAKF method shows favorable convergence and can achieve accurate estimation with less than 5% relative errors, and the superiority over AKF in computation cost is also observed. [ABSTRACT FROM AUTHOR]

The finite element limit analysis solution presented in this paper offers novel approaches for estimating the ultimate bearing capacity of annular foundations on Hoek–Brown criterion. The study examines the effects of five of dimensionless parameters, including the ratio of internal to external radii, the depth ratio, the adhesive factor, the yield parameter, and the geological strength index, on the findings of bearing capacity as well as the processes of collapse. Furthermore, one of the soft-computing regression methodologies, the multi-objective evolutionary polynomial regression analysis (MOGA-EPR) method, is utilized along with the requirement of the FELA outcomes as input data. This paper provides accurate limit-state predictions for annular footings on diverse rock masses using the MOGA-EPR model. By using the MOGA-EPR approach, the findings are highly precise and trustworthy, empowering designers to choose the best annular foundation design for various Hoek–Brown material varieties. Moreover, this study extends its scope by encompassing the application of multiple linear regression, multiple nonlinear regression, and artificial neural network models for an extensive comparative analysis. The amalgamation of these models widens the evaluative framework, fostering a more comprehensive exploration of predictive capabilities and insights into the stability assessment of annular footings across rock mass conditions. Through this multifaceted approach, a holistic comprehension emerges, thereby enhancing the decision-making process pertaining to the design of annular foundations within diverse Hoek–Brown material contexts. [ABSTRACT FROM AUTHOR]

This paper designs, analyzes, and implements a finite element analysis for the simulation of the nonlinear advection-diffusion model. The key feature of the proposed work is to provide novel a priori error estimates in Bôchner norms L 2 (0 , T ; H 0 1 (Ω)) and L ∞ (0 , T ; H 0 1 (Ω)) simultaneously. To achieve the desired error estimates for both semidiscrete and fully discrete schemes, our idea is to introduce the Ritz projection operator that allows us to enforce the known estimates for P 1 and P 2 finite elements in the formulation of the desired results. Further, this paper establishes the stability, existence, and uniqueness in the precise normed spaces. Finally, we prove the fully discrete error estimates using the Backward Euler and Crank-Nicolson's schemes which are corroborated by numerical experiments to validate the developed theory on various domains for both schemes. To the best of author's knowledge, this is the first finite element simulation that provides the estimates in the L 2 Bôchner norm for any such types of time-dependent problems. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to make a contribution towards reducing the deflections of silicon wafers. The deformation of silicon wafers used in the manufacture of electronic micro-components is one of the most common problems encountered by industrialists during manufacturing. Stack warping is typically produced during the process of depositing thin layers on a substrate. This is due to the thermal-mechanical stresses caused by the difference between the thermal expansion coefficients of the materials. Reducing wafer deformation is essential to increase reliability and improve quality. In this paper, the authors propose an approach based on minimal geometrical modifications to reduce the deformation of a silicon wafer coated with two thin layers. Numerical finite element models have been developed to evaluate the impact of geometrical modifications on warping amplitude. Finite element models have been validated compared with experimental models. The results obtained are encouraging and clearly show a considerable reduction in wafer deformation. Design/methodology/approach: Reducing wafer deformation is essential to increase reliability and improve quality. In this paper, the authors propose an approach based on minimal geometrical modifications to reduce the deformation of a silicon wafer coated with two thin layers. Numerical finite element models have been developed to evaluate the impact of geometrical modifications on warping amplitude. Finite element models have been validated compared with experimental models. Findings: The results obtained are encouraging and clearly show a considerable reduction in wafer deformation. Originality/value: This paper describes the influence of geometric modification on wafer deformation. The work show also the cruciality of stress reduction in the purpose to obtain less wafer deformation. [ABSTRACT FROM AUTHOR]

In this paper, the flow of an incompressible fluid is thermally studied. Investigations into the heat transfer process have been conducted in non-Newtonian fluid flows with chemical reactions and heat sources present. The application of this work is the fluid flow around the stretching sheet; fluid flow on a stretching sheet can be applied to polymer extrusion, drawing or plastic films, hot rolling, casting and other engineering problems. The novelty of this paper is that the governing equations have been solved by a new and efficient semi-analytical approach, the Akbari–Ganji method (AGM). In order to investigate the issue, the finite element method (FEM) has also been applied. Comparing the results of problem-solving with the applied methods with the results of the previous research shows a perfect agreement. The results show that the parameters of Hartmann number and interaction improve the velocity profiles. Additionally, for greater Hartmann number values, raising the parameter of interaction decreases the temperature value, but a smaller value has the reverse effect. As the Hartmann number increases, the fluid velocity decreases and it shows that with the increase of electromagnetic force, the velocity of fluid flow decreases. [ABSTRACT FROM AUTHOR]

Determining the mechanical properties of a composite material represents an important stage in its design and is generally a complicated operation. These values are influenced by the topology and geometry of the resulting composite and the values of the elastic constants of the components. Due to the importance of this subject and the increasing use of composite materials, different calculation methods have been developed over the last fifty years. Some of the methods are theoretical, with results that are difficult to apply in practice due to difficulties related to numerical calculation. In the current paper, using theoretical results offered by the homogenization theory, values of engineering elastic constants are obtained. The finite element method (FEM) is used to determine the stress and strain field required in these calculations; this is an extremely powerful and verified calculation tool for the case of a material with any type of structure and geometry. In order to minimize errors, the paper proposes the method of least squares, a mathematical method that provides the best estimate for the set of values obtained by calculating FEM. It is useful to consider as many load cases as possible to obtain the best estimates. The elastic constants for a transversely isotropic material (composite reinforced with cylindrical fibers) are thus determined for a real case. [ABSTRACT FROM AUTHOR]

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]

In order to further study the cushioning performance of concave hexagonal cores (CHCs) and expand their application range, the in-plane finite element model of CHCs is established in this paper. A dynamic cushioning coefficient method was proposed to characterize the cushioning performance of CHCs. The dynamic cushioning coefficient curve and minimum dynamic cushioning coefficient (MDCC) of CHCs with different impact velocities and structural parameters are obtained. The influence rules of structural parameters and impact velocities on the MDCC are analyzed; the deformation mode and transformation empirical formula are also obtained. The results show that when other parameters are constant, the MDCC of CHCs decreases with the increase of impact velocity, increases with the increase of wall thickness and side length ratio, and decreases with the increase of expansion angle. The theoretical analysis is consistent with the finite element results, which further verifies the reliability of the model. This paper provides a solid theoretical basis for the industrial application of the cushioning performance of CHCs and forms a key technical support. [ABSTRACT FROM AUTHOR]

Purpose: In a coaxial ultrasonic flow sensor (UFS), wall thickness is a vital parameter of the measurement tube, especially those with small inner diameters. The paper aims to investigate the influence of wall thickness on the transient signal characteristics in an UFS. Design/methodology/approach: First, the problem was researched experimentally using a series of measurement tubes with different wall thicknesses. Second, a finite element method–based model in the time domain was established to validate the experimental results and further discussion. Finally, the plane wave assumption and oblique incident theory were used to analyze the wave propagation in the tube, and an idea of wave packet superposition was proposed to reveal the mechanism of the influence of wall thickness. Findings: Both experimental and simulated results showed that the signal amplitude decreased periodically as the wall thickness increased, and the corresponding waveform varied dramatically. Based on the analysis of wave propagation in the measurement tube, a formula concerning the phase difference between wave packets was derived to characterize the signal variation. Originality/value: This paper provides a new and explicit explanation of the influence of wall thickness on the transient signal in a co-axial UFS. Both experimental and simulated results were presented, and the mechanism was clearly described. [ABSTRACT FROM AUTHOR]

The injection of the Direct Current (DC) bias component will lead to oversaturation of the transformer core and affect its safe operation. In this paper, the vector magnetic potential A and winding current I are used as the variables solved in the time-step finite element method to simulate the nonlinear transient magnetization characteristics of the transformer under DC bias, and the fixed-point reluctivity is introduced to deal with the nonlinear iterative problem. The field-circuit coupling relationship is established through the electromagnetic induction law, and the two-dimensional time-step finite element model of the transformer core is found. The dynamic J–A hysteresis model is used to deal with the hysteresis effect of iron cores. The fixed-point reluctivity of difference form is introduced to solve the problem of uneven transition and multi-value of magnetization curve with hysteresis in the iterative process. The determination scheme for the equivalent thickness of the core model and the initial iterative value are discussed. A laminated core transformer is made for experiments, and the accuracy and applicability of the model proposed in this paper are verified by comparing the calculation and experimental results. The influence of different voltages and different DC bias components on the electromagnetic characteristics of the transformer is analyzed. [ABSTRACT FROM AUTHOR]

This paper summarizes the effective components of computer-aided design and computer-aided manufacturing (CAD-CAM) resin composites that contribute to achieving greater mechanical properties and further development. In silico multi-scale analysis, in silico nonlinear dynamic finite element analysis (FEA), and artificial intelligence (AI) were used to explore the effective components of CAD-CAM resin composites. The effects of the filler diameter and silane coupling ratio on the mechanical properties of CAD-CAM resin composites have been clarified through multi-scale analysis. The effects of the filler contents, and filler and monomer compositions have been investigated by AI algorithms. The fracture behavior of CAD-CAM composite crown was analyzed using in silico non-linear dynamic FEA. The longevity of CAD-CAM composite crown was assessed through step-stress accelerating life testing (SSALT). As the filler diameter decreases, there is an increase in elastic moduli and compressive strengths at the macroscale. At the nanoscale, a decrease in the filler diameter results in a decrease in the maximum value of the maximum principal strain. When the silane coupling ratio decreases, there is a decrease in the elastic modulus and compressive strength. According to the exhaustive search and feature importance analysis based on the AI algorithm, the combination of certain components was narrowed down to achieve a flexural strength of 269.5 MPa. The in silico non-linear FEA successfully detected the sign of the initial crack of the CAD-CAM composite molar crown. The SSALT revealed that CAD-CAM resin composite molar crowns containing nanofillers with a high fraction of resin matrix demonstrated great longevity. This paper summarized the effective components of CAD-CAM resin composites for their further development. The integration of in vitro and in silico approaches will expedite the advancement of CAD-CAM resin composites, offering benefits such as time efficiency and reduction of material waste for researchers and manufacturers. • The effective components of CAD-CAM resin composites (RC) have been summarized. • A smaller filler and a high silane coupling ratio enhance the mechanical properties of CAD-CAM RC. • Non-linear FEA has detected the sign of the initial crack in the CAD-CAM composite crown. • AI has been utilized to narrow down the effective components that achieve high flexural strength. • CAD-CAM composite crowns with a high fraction of resin matrix demonstrate remarkable longevity. [ABSTRACT FROM AUTHOR]

In this paper, a software framework is presented through an application that is able to jointly optimize an electric motor and a gearbox for the design of a drive system for electric vehicles. The framework employs a global optimization method and uses both analytical and finite element method (FEM) models to evaluate the objective functions. The optimization process is supported by a statistical surrogate model, which allows a large reduction of runtime. An earlier version of this framework was only suitable for electric motor optimization. In the application presented in a previous paper, the motor of a belt-driven electric drive system was optimized. In this paper, the optimization of the same drive system is shown, but now with a combined optimization of a gear drive and motor. The objective functions of optimization are minimizing the total loss energy and the weight of the drive system. The optimization results are compared with previous results to demonstrate the further potential of joint optimization. [ABSTRACT FROM AUTHOR]

For insulated gate bipolar transistor (IGBT) modules using wire bonding as the interconnection method, the main failure mechanism is cracking of the bonded interface. Studying the mechanical properties of the bonded interface is crucial for assessing the reliability of IGBT modules. In this paper, first, shear tests are conducted on the bonded interface to test the bonded interface's strength. Then, finite element–cohesive zone modeling (FE-CZM) is established to describe the mechanical behavior of the bonded interface. A novel machine learning (ML) architecture integrating a convolutional neural network (CNN) and a long short-term memory (LSTM) network is used to identify the shape and parameters of the traction separation law (TSL) of the FE-CZM model accurately and efficiently. The CNN-LSTM architecture not only has excellent feature extraction and sequence-data-processing abilities but can also effectively address the long-term dependency problem. A total of 1800 sets of datasets are obtained based on numerical computations, and the CNN-LSTM architecture is trained with load–displacement (F–δ) curves as input parameters and TSL shapes and parameters as output parameters. The results show that the error rate of the model for TSL shape prediction is only 0.186%. The performance metric's mean absolute percentage error (MAPE) is less than 3.5044% for all the predictions of the TSL parameters. Compared with separate CNN and LSTM architectures, the proposed CNN-LSTM-architecture approach exhibits obvious advantages in recognizing TSL shapes and parameters. A combination of the FE-CZM and ML methods in this paper provides a promising and effective solution for identifying the mechanical parameters of the bonded interfaces of IGBT modules. [ABSTRACT FROM AUTHOR]

In order to solve the deficiencies of traditional board-level assembly CubeSat, such as low modularity, complex assembly process and poor scalability, a sandwich module assembly structure and method with no drive components is proposed, which can achieve quick connection and flexible assembly between modules. First, the proposed CubeSat standard module can be compatible with the standard interface of traditional CubeSat. The 4-in-1 interface of Mechanical-Electrical-Thermal-Data does not occupy the internal space of the standard module, and the electrical and thermal interfaces meet the requirements of CubeSat in-orbit work. Secondly, in order to improve the reliability of the connection between the modules, a plug-in connection scheme of the mechanical interface was designed. Finally, a genetic algorithm was used to optimize the interface size, so that it has better plug-in performance. The simulation results show that the performance of the male interface of titanium alloy material is the best, and the error between the finite element analysis and genetic algorithm results is less than 4.8 %, which is consistent with the actual tensile test results of the optimized prototype, and meets the mechanical requirements of the launch process and space orbit operation for CubeSat. The test results can guide production and provide a reference for subsequent engineering applications of CubeSat modular assembly. • In this paper, a standardized modular assembly method of CubeSat sandwich structure is designed. The assembly structure does not include driving parts, is simple in form, can be quickly connected, is flexible in assembly mode, and does not occupy the internal space of the standard module. • A standard 4-in-1 connection device was designed in this paper, including four interfaces: mechanical, electrical, thermal and data, which can achieve "plug and play". • This paper uses genetic algorithm to optimize the structure of the mechanical connection male joint, and obtains the optimal configuration of the male joint. This ensures the reliability, firmness and stability of mechanical connections, and meets the mechanical requirements of CubeSats during launch and in orbit. [ABSTRACT FROM AUTHOR]

The reliability of high-voltage circuit breakers (HVCBs) depends critically on the dynamic characteristics of their hydraulic operating mechanisms (OMs). However, previous analyses have been limited to discrete components due to the lack of models capturing multi-physics couplings. This paper proposes a novel co-simulation approach for hydraulic OMs that enables system-level analysis. Specifically, the hydraulic system is modelled using the lumped parameter method, and the transmission mechanism is modelled via finite element analysis. The subsystem models exchange inputs and outputs through shared memory, realizing coupling without compromising simulation performance. Experiments on a 550 kV HVCB validate that the model accurately captures OM transient responses. The co-simulation framework has diverse capabilities, including predicting dynamics under varied operating parameters and quantifying stress distributions and response evolution patterns. Overall, this paper proposes an advanced multi-physics analysis capability for hydraulic OMs to support reliabilityoriented design and optimization. [ABSTRACT FROM AUTHOR]

The bone lacunar-canalicular system (LCS) is a unique complex 3D microscopic tubular network structure within the osteon that contains interstitial fluid flow to ensure the efficient transport of signaling molecules, nutrients, and wastes to guarantee the normal physiological activities of bone tissue. The mass transfer laws in the LCS under microgravity and hypergravity are still unclear. In this paper, a multi-scale 3D osteon model was established to mimic the cortical osteon, and a finite element method was used to numerically analyze the mass transfer in the LCS under hypergravity, normal gravity and microgravity and combined with high-intensity exercise conditions. It was shown that hypergravity promoted mass transfer in the LCS to the deep lacunae, and the number of particles in lacunae increased more significantly from normal gravity to hypergravity the further away from the Haversian canal. The microgravity environment inhibited particles transport in the LCS to deep lacunae. Under normal gravity and microgravity, the number of particles in lacunae increased greatly when doing high-intensity exercise compared to stationary standing. This paper presents the first simulation of mass transfer within the LCS with different gravity fields combined with high-intensity exercise using the finite element method. The research suggested that hypergravity can greatly promote mass transfer in the LCS to deep lacunae, and microgravity strongly inhibited this mass transfer; high-intensity exercise increased the mass transfer rate in the LCS. This study provided a new strategy to combat and treat microgravity-induced osteoporosis. [ABSTRACT FROM AUTHOR]

Grinding damage of hard and brittle materials has a direct impact on part strength and subsequent polishing efficiency. Damage suppression is one of the key research issues in hard and brittle material processing. Due to the uncertain damage evolution law, there is still a lack of optimization methods for the multi-step grinding process under given damage constraints. In this paper, the extended finite element method is used to establish a model between the prefabricated crack depth and final crack depth, which reveals the influence of various existing subsurface damages on crack propagation. It is found that only when the prefabricated crack depth is close to the indentation crack depth on the perfect surface, the final crack depth will be affected to some extent. To optimize the grinding process to achieve low damage, a semi-empirical model for predicting grinding damage is proposed which is suitable for process optimization and does not rely on some difficult-to-obtain parameters. Finally, based on the damage evolution law and prediction model, the core content of this paper is proposed, that is, a multi-step grinding process optimization method with variable grinding depth. This method can minimize the damage while ensuring the same processing efficiency, the damage depth is reduced by 25 %. The effectiveness of the optimization method and the correctness of the damage evolution law are proved by experiments. This method is suitable for engineering applications and has practical significance for understanding the damage evolution mechanism, which is helpful for the suppression of grinding damage and the optimization of the grinding process. • Reveal the evolution mechanism of various existing subsurface damage on crack propagation by XFEM. • Propose a semi-empirical model for grinding damage prediction suitable for process optimization. • Propose a multi-step grinding process optimization method for hard brittle materials with variable grinding depth. • Prove the effectiveness of the optimization method and the evolutionary model through experiments. [ABSTRACT FROM AUTHOR]

In this paper, further in-depth research on chip formation mechanism is conducted on the cutting of metallic glasses. The study of chips contributes to a better understanding of the machining nature of materials, which is of significant importance for improving product quality, reducing energy consumption, and resource utilization. This paper employs a combination of simulation and experimental methods, wihch not only analyzes the mechanism of chip formation in depth, but also investigates the time-varying characteristics of cutting forces. The results indicate that, when comparing simulation with experiments, the average error in cutting forces is 7.62%, and the chip morphology is also quite similar. Observations in the simulation show that as the cutting thickness increases from 7.96 μm to 23.87 μm, the free surface of the chip exhibits serrated features, and the main shear zone of the chip becomes clearer. Cutting forces exhibit periodic variations, with alternating peaks and valleys representing the formation of shear zones in the chip. In the experiment, observed chips displays a wrinkled free surface and a smooth non-free surface, with some chip edges exhibiting a burr phenomenon. By selecting appropriate machining parameters, the generation of secondary shear bands on the free surface was effectively reduced. By observing the chip morphology, it is found that the chip formation is accompanied by the material removal of plasticity and brittleness, which is the result of the combined action of heat, stress, and free volume. It should be considered to lower temperature to reduce the phenomenon of chip adhesion, providing guidance for further optimizing the cutting process of metallic glass. This paper can provide to readers further understanding of the chip formation mechanism in milling metal glass. • 2D finite element modeling was used to simulate the chip formation. • The shear zones appeared on the serrated chips. • The experimental results verified the accuracy of the simulation model. • The chips of BMG have smooth non-free surface and wrinkled free surface. • The serrated chips are the result of heat, stress, and free volume. [ABSTRACT FROM AUTHOR]

This paper proposes probabilistic demand models to assess fragilities for high-rise buildings with three types of outrigger systems under seismic and wind loads. Parameters of the structural model are determined based on the structural material and geometric conditions. Parameters of the excitation model are determined based on the hazard characterization that varies with the hazard type. This paper involves three types of hazards: high-frequency ground motions, near-fault ground motions, and stochastic wind loads. With the input information from the structural model and the excitation model, 3D finite element models are built and computed using ANSYS to obtain structural responses (output information). Based on a database with the input-output pair obtained, we formulate probabilistic demand models for high-rise buildings with three types of outrigger systems under three types of hazards. These probabilistic models are proposed to estimate three response quantities of interest, the maximum inter-story drift, the maximum top acceleration, and the maximum top displacement. They, therefore, include univariate, bivariate, and tri-variate models. The probabilistic demand models account for both aleatory and epistemic uncertainties and provide unbiased estimates. With a direct and parsimonious formula, they have high accuracy and are extremely convenient to be used in practical engineering. They are finally used to formulate fragility estimates with bounds for an example high-rise building with three types of outrigger systems under three types of hazards. The results indicate that damped outrigger systems can effectively reduce fragilities for high-rise buildings under three types of hazards. [ABSTRACT FROM AUTHOR]

In electron optics, calculation of the electric field plays a major role in all computations and simulations. Accurate field calculation methods such as the finite element method (FEM), boundary element method and finite difference method, have been used for years. However, such methods are computationally very expensive and make the computer simulation challenging or even infeasible when trying to apply automated design of electrostatic lens systems with many free parameters. Hence, for years, electron optics scientists have been searching for a fast and accurate method of field calculation to tackle the aforementioned problem in the design and optimization of electrostatic electron lens systems. This paper presents a novel method for fast electric field calculation in electrostatic electron lens systems with reasonably high accuracy to enable the electron-optical designers to design and optimize an electrostatic lens system with many free parameters in a reasonably short time. The essence of the method is to express the off-axis potential in an axially symmetrical coordinate system in terms of derivatives of the axial potential up to the fourth order, and equate this to the potential of the electrode at that axial position. Doing this for a limited number of axial positions, we get a set of equations that can be solved to obtain the axial potential, necessary for calculating the lens properties. We name this method the fourth-order electrode method because we take the axial derivatives up to the fourth order. To solve the equations, a quintic spline approximation of the axial potential is calculated by solving three sets of linear equations simultaneously. The sets of equations are extracted from the Laplace equation and the fundamental equations that describe a quintic spline. The accuracy and speed of this method is compared with other field calculation methods, such as the FEM and second order electrode method (SOEM). The new field calculation method is implemented in design/optimization of electrostatic lens systems by using a genetic algorithm based optimization program for electrostatic lens systems developed by the authors. The effectiveness of this new field calculation method in optimizing optical parameters of electrostatic lens systems is compared with FEM and SOEM and the results are presented. It should be noted that the formulation is derived for general axis symmetrical electrostatic electron lens systems, however the examples shown in this paper are with cylindrical electrodes due to the simplicity of the implementation in the software. [ABSTRACT FROM AUTHOR]

This paper presents a computer-based methodology to support the design for additive manufacturing of metal components. Metal additive manufacturing, and in particular powder bed fusion systems, are playing a prominent role in the industry 4.0 scenario. The state of the art concerning design methods and tools to support design for additive manufacturing is reviewed by the authors. The key phases of product design and process design to achieve lightweight functional designs and reliable processes are deepened, and the computer-aided technologies to support the approaches implementation are described. Indeed, the state of the art design for additive manufacturing general workflow can be enriched by holistic approaches, use of numerical simulation, and integration and automation between the required tasks. The paper provides a methodology based on the systematic use of numerical simulation to achieve the optimization of both products and associated processes. To take advantage of the holistic perspective, the approach relies on the use of integrated product-process design platforms, allowing to streamline the digital process chain. Product design is based on the systematic integration of topology optimization and automatized tools for concept development and selection and subsequent product simulation driven design refinement. Process design is based on a systematic use of process simulation to prevent manufacturing flaws related to the high thermal gradients of metal processes and minimize residual stress and deformations. This is achieved by working on both the build cycles layouts and the 3D models' distortion compensation. An automotive use case of product and process design performed through the proposed simulation-driven integrated approach is provided to assess the actual method suitability for effective re-designs of additive manufacturing high-performance metal products. The bridged gaps are systematically outlined, and further developments are discussed. [ABSTRACT FROM AUTHOR]

Determining the properties of composite materials (knowing the properties of the component phases) is a primary objective in the design phase. Numerous methods have been developed to determine the elastic constants of a composite material. All these methods are laborious and require significant computing time. It is possible to make experimental measurements, but these too are expensive and time-consuming. In order to have a quick estimate of the value of the engineering constants of a new composite material (in our study a polymeric matrix reinforced with carbon fibers), this paper proposes a quick method for determining the homogenized material constants, using the finite element method (FEM). For this, the eigenfrequencies of a beam specimen manufactured by the studied composite material will be computed using FEM. The model will consider both phases of the composite, with the geometry and real size. The mechanical properties of the constituent's material phases are known. With the help of this model, the torsional, longitudinal and transverse vibrations of the beam are studied. Based on the eigenvalues obtained by this calculation, it now is possible to quickly estimate the values of homogenized material constants required in the design. An example for a fiber-reinforced polymer composite material is provided in the paper. [ABSTRACT FROM AUTHOR]

Purpose: The rock drill's drill tail experiences high-frequency fretting simultaneously in the rotational and axial directions. Due to the complex working characteristics and the low viscosity of the water medium, the pure water seal is susceptible to damage and failure. The purpose of this paper is to enhance the water seal's performance. Design/methodology/approach: The Y-shaped seal ring is modeled and simulated using orthogonal testing. Through analysis of the impact of various seal section parameters on sealing performance, the maximum contact stress and maximum Von Mises stress are selected as indicators of sealing effectiveness. Findings: The maximum contact stress is proportional to lip thickness and chamfer length but inversely proportional to lip length. Meanwhile, the maximum Von Mises stress is directly influenced by lip depth and the included angle of the lip and drill tail but is inversely proportional to the lip thickness. The enhanced Y-shaped water seal sees reductions of 15% and 45% in maximum contact stress and maximum Von Mises stress, respectively. Originality/value: This paper used analytical method and model that is helpful for design of the water seal's structure in complex working characteristics and the low viscosity of the water medium. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2023-0366/ [ABSTRACT FROM AUTHOR]

Based on the classical grid theory and related regulations, a structure model of a fiber-wound composite gas cylinder was designed in this paper. Based on the design results, a finite element model of a fully wound composite cylinder of an aluminum alloy inner liner with a working pressure of 35 MPa was established based on the ABAQUS software, and its stress distribution under working pressure and minimum burst pressure was analyzed. According to engineering experience, the pressure tolerance of composite cylinders can be improved by proper autofrettage pressure before working pressure, so the influence of autofrettage pressure was analyzed in this paper. The optimum autofrettage pressure was selected by setting the autofrettage gradient, and damage analysis was carried out on the cylinder with nominal working pressure of 35 MPa based on the Hashin failure criterion. The results show the initial damage sequence: matrix stretching occurs before the fiber stretching, and the damage generally starts from the spiral-wound layer. The tensile damage first appears in the transition section between the head and the barrel body, and the damage of the spiral-wound layer develops from the inner layer of the wound layer to the outer layer, while the damage of the circumferentially wound layer develops from the outer layer to the inner layer. [ABSTRACT FROM AUTHOR]

Strip shape control is a hotspot and challenge in strip rolling, where the development trend of rolling technology is towards high strength, high toughness, and a large width-to-thickness ratio. The influence of material microstructure evolution on strip shape control is being increasingly emphasized. In this paper, a Nb-Ti microalloyed steel is taken as the research object. Thermodynamic and kinetic models focusing on the precipitation of the austenite phase are established to quantify the precipitation process. A coupled model of rolls and strips is built using ABAQUS 2022 software, where the precipitation strengthening model and high-temperature constitutive model are embedded into the finite element model (FEM) through subroutines. A two-dimensional alternating differential model is employed to acquire real-time temperature differences in the width direction of the strip. The effects of precipitation inclusion and exclusion on the strip crown under different operating conditions are compared and analyzed. The results indicate that as the temperature decreases, the strengthening effect increases, reaching around 40 MPa at temperatures above 1000 °C and 96.6 MPa at 800 °C. Furthermore, the inclusion of crown in the precipitation consideration is more sensitive to overall temperature changes, but as the strip width decreases, the sensitivity of crown to temperature decreases. The research findings of this paper provide guidance for improving strip shape control and reducing abnormalities during the rolling process. [ABSTRACT FROM AUTHOR]