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Metal nanocages exhibit localized surface plasmon resonance that strongly absorbs and scatters light at specific wavelengths, making them potentially valuable for photothermal therapy and biological imaging applications. However, investigations on metal nanocages are still confined to high-cost and small-scale synthesis. The comprehensive analysis of optical properties and optimal size parameters of metal nanocages is rarely reported. This paper simulates the effects of materials (Ag, Au, and Cu), size parameters, refractive index of the surrounding medium, and orientation on the light absorption and scattering characteristics of the nanocages using the finite-element method and the size-dependent refractive-index model for metal nanoparticles. The results show that the Ag nanocages have excellent light absorption and scattering characteristics and respond significantly to the size parameters, while the refractive index and orientation of the surrounding medium have less effect on them. The Au nanocages also possess superior light absorption properties at specific incident wavelengths. This study also identified the optimized sizes of three metal nanocages at incident light wavelengths commonly used in biomedicine; it was also found that, under deep therapy conditions, Ag nanocages in particular exhibit the highest volume absorption and scattering coefficients of 0.708 nm−1 and 0.583 nm−1, respectively. These findings offer theoretical insights into preparing target nanocage particles for applications in photothermal therapy and biological imaging. [ABSTRACT FROM AUTHOR]

Dynamic neutralizers, also known as dynamic absorbers, are efficient means of mitigating vibrations in structures. They have been particularly effective in addressing broad-band passive vibration control in structures with high modal density through the use of multi-degrees of freedom (MDoF) and viscoelastic materials (VEMs). Therefore, sandwich-type or constrained-layer beams can offer great potential when used as MDoF control devices. However, there is limited literature exploring these structures as auxiliary systems, with coupling typically assumed to be single-point and limited to only translational degrees of freedom (DoFs). In this context, this article presents a methodology to determine the dynamic behavior of a compound system, coupling the displacement and rotation DoFs between a metal structure–referred to as the primary system–and a MDoF auxiliary system. The coupling is achieved by utilizing an equivalent dynamic stiffness obtained at the base of the auxiliary system through ANSYS finite-element software, providing a robust and comprehensive approach. A Matlab code transfers the auxiliary system's geometry and properties to ANSYS, where the dynamic stiffness at the base is determined and subsequently coupled to the primary system. A MDoF auxiliary system of the constrained-layer type with VEM was studied, and both single-point and distributed coupling were analyzed. The auxiliary system was attached to a cantilever metal beam for numerical and experimental validation. The proposed generalized equivalent dynamic stiffness model accurately estimates the response of the compound system, offering a 25% reduction in response computation time compared to the finite-element model of the complete compound system. This methodology enables the accurate representation of compound system dynamics while minimizing computational time, making it valuable for the optimal design of a set of MDoF viscoelastic dynamic neutralizers. [ABSTRACT FROM AUTHOR]

Inspired by buckle-induced structural deformation, a new type of tensegrity robot using bending bars is proposed. First, a combination of numerical calculation and the finite-element simulation method was adopted to determine the influence of geometric parameters on equivalent stiffness, and the basic configuration parameters were determined. Then, the tensegrity dynamical model and the ground contact model were established using a nonlinear finite-element method, and four rolling gaits of the robot were realized by driving diagonal cables. Finally, an experimental prototype of the bending bar tensegrity robot was built for rolling gait experiments. The results show that the experimental rolling motion is in good agreement with the theoretical model. Through continuous curve path rolling, the minimum turning radius of the robot was determined, and the motion mode of the prismatic tensegrity robot was enriched. Practical Applications: Tensegrity structure is a self-balancing system composed of compression bars and tension cables, which has aroused numerous scholars' research interest in civil architecture, mechanical engineering, aerospace, biomedical, and other fields. The results cover model design, form-finding analysis, static equilibrium stability analysis, optimization design, dynamic response analysis, and so on. In fact, when the tensegrity mechanism is applied to a mobile robot, a change in shape can be achieved by shortening some cables with the actuator, so the system's stiffness contradicts the ability to deform. The focus of this work is to propose a new type of bending bar design that can replace the spring to meet the needs of large deformation and avoid weakening the structure's overall stiffness. This design realizes the rolling motion mode of the robot and can be applied to the motion mode of other prismatic tensegrity robots. [ABSTRACT FROM AUTHOR]

The real-time, full-field simulation of the tube hydroforming process is crucial for deformation monitoring and the timely prediction of defects. However, this is rather difficult for finite-element simulation due to its time-consuming nature. To overcome this drawback, in this paper, a surrogate model framework was proposed by integrating the finite-element method (FEM) and machine learning (ML), in which the basic methodology involved interrupting the computational workflow of the FEM and reassembling it with ML. Specifically, the displacement field, as the primary unknown quantity to be solved using the FEM, was mapped onto the displacement boundary conditions of the tube component with ML. To this end, the titanium tube material as well as the hydroforming process was investigated, and a fairly accurate FEM model was developed based on the CPB06 yield criterion coupled with a simplified Kim–Tuan hardening model. Numerous FEM simulations were performed by varying the loading conditions to generate the training database for ML. Then, a random forest algorithm was applied and trained to develop the surrogate model, in which the grid search method was employed to obtain the optimal combination of the hyperparameters. Sequentially, the principal strain, the effective strain/stress, as well as the wall thickness was derived according to continuum mechanics theories. Although further improvements were required in certain aspects, the developed FEM-ML surrogate model delivered extraordinary accuracy and instantaneity in reproducing multi-physical fields, especially the displacement field and wall-thickness distribution, manifesting its feasibility in the real-time, full-field simulation and monitoring of deformation states. [ABSTRACT FROM AUTHOR]

In this research, we present the results of analyzing the technical feasibility of an old invention by Henry Muncaster from the perspective of mechanical engineering, specifically focusing on the resistance of materials. The invention is a two-cylinder steam engine with a parallel motion crosshead, for which plans were published in the Model Engineer magazine in 1957. This complex device, composed of 76 elements and lacking descriptive information, has been the subject of a recent article that illustrated its design through the engineering drawing discipline and a 3D CAD model. To provide reliable information and conduct a comprehensive study of its technical feasibility, an extensive linear static analysis was performed. This analysis considered two critical positions of the piston inside the cylinder: upper dead center and lower dead center. We determined the optimal range of working pressures necessary to achieve a safety factor within the optimal design range of two to four. The results include von Mises stresses, displacements, and safety factor distributions, confirming that the optimal working pressure range for steam intake is between 1.885 and 3.550 MPa. This ensures that the safety factor values remain between 2.01 and 3.78. [ABSTRACT FROM AUTHOR]

The present work is a contribution to the study of the effects of temperature on vibrations and stability of laminated composite plates using the finite element method. Thus, a DMQP/ml bending finite element with 4 nodes and 3 degrees of freedom based on the first order shear theory is extended to consider the effects of temperature on vibration and stability of laminated composite plates. The effect of the dependence of material properties on temperature as well as the effect of the of thermal stresses on the natural frequencies of laminated plates are studied simultaneously. A parametric study was carried out to highlight the effect of certain parameters on the vibration behavior of the laminated plates. The study showed that in most cases, the natural frequencies of vibration decrease with the increase in temperature. On the other hand, if the temperature inflicted on the plate coincides with the critical buckling temperature, the natural frequencies tend towards zero. Moreover, based on experimental data, this paper presents a study of the effect of temperature on the vibration behavior of a laminated T300/5208 Graphite/Epoxy plate. The study showed that temperature significantly changes the properties of the materials as well as the vibration behavior of the plate.

Numerical investigation of free-standing cantilever walls subjected to horizontal seismic loads was carried out using nonlinear elastoplastic finite-element approach. The numerical model was validated using centrifuge tests and a numerical study. This study emphasizes the acceleration response, deformation mechanism, and active earth thrust (Pae) of seismically induced cantilever retaining walls. A detailed parametric study was conducted to analyze the effect of the entire earthquake motion, wall dimensions, and soil characteristics on the active earth thrust behind the wall stem (Pae_stem) and along the virtual plane passing through the wall heel (Pae_vp). The study found that the Pae_stem and Pae_vp decrease with an increase in peak ground acceleration (PGA) up to approximately 0.55 g because they are impacted significantly by the translational and rotational displacement of the cantilever wall. In addition, the magnitude of Pae_stem is smaller than that of Pae_vp. Based on the parametric investigation and regression analysis, an equation for Pae_stem and Pae_vp is proposed and was verified by comparing it with the results of the finite-element study and existing numerical work. The proposed equation provides improved prediction of the active earth thrust of a cantilever wall at an early design stage. [ABSTRACT FROM AUTHOR]

The present work is a contribution to the study of the effects of temperature on vibrations and stability of laminated composite plates using the finite element method. Thus, a DMQP/ml bending finite element with 4 nodes and 3 degrees of freedom based on the first order shear theory is extended to consider the effects of temperature on vibration and stability of laminated composite plates. The effect of the dependence of material properties on temperature as well as the effect of the of thermal stresses on the natural frequencies of laminated plates are studied simultaneously. A parametric study was carried out to highlight the effect of certain parameters on the vibration behaviour of the laminated plates. The study showed that in most cases the natural frequencies of vibration decrease with the increase in temperature. On the other hand, if the temperature inflicted on the plate coincides with the critical buckling temperature, the natural frequencies tend towards zero. Moreover, based on experimental data, this paper presents a study of the effect of temperature on the vibration behaviour of a laminated T300/5208 Graphite/Epoxy plate. The study showed that temperature significantly changes the properties of the materials as well as the vibration behaviour of the plate. [ABSTRACT FROM AUTHOR]

The dynamics of three-layer cylindrical elements with an inhomogeneous filler rested on the Winkler elastic foundation under various boundary conditions is studied. The distances between ribs in the light filler are much larger than the dimensions of the ribs cross-sections. Because of this, the theory of independent static and kinematic hypotheses is applied to each layer. In accordance with the Hamilton-Ostrogradsky variational principle the motion equations of the three-layer cylindrical shells rested on the Winkler elastic foundation and natural boundary conditions are obtained using the models of Timoshenko's shell and rod theory. This made it possible to produce an adequate finite-element model for three-layer cylindrical shells of different materials and obtained numerical results of the nature of dynamic behavior of a three-layer structure on an elastic foundation by employing the finite element method. The influence of the physical-mechanical parameters of layers of cylindrical structures on natural frequencies, methods of fastening their ends, parameter of shells elastic foundation on their dynamics under axisymmetric internal impulsive loading is investigated. New mechanical effects are revealed. [ABSTRACT FROM AUTHOR]

Advancements in audiology and medical engineering have generated growing interest in enhancing titanium implants for middle ear restoration. In our study, we employed a finite element model of the middle ear to assess the behavior of the TORP prosthesis and the stapes under an acoustic pressure of 90 dB across a frequency range of 250 to 8000 Hz. The results were compared to experimental measurements obtained using a Doppler-effect-based laser vibrometer while varying the materials of the prosthesis to evaluate their mechanical impact. A satisfactory correlation between the simulation and experimental measurements validated our model [ABSTRACT FROM AUTHOR]

When designing steel members with nonsymmetric cross sections, it is essential to consider twisting effects when performing stability checks via second-order analysis according to the ANSI/AISC 360-22. Existing line-element formulations for nonsymmetric sections are mostly derived based on thin-walled assumptions, leading to an overestimation of member strength due to the inaccurate prediction of member behavior, especially when the cross sections have moderate wall thickness. This paper proposes an efficient line-element method for second-order analysis of steel members with nonsymmetric thick-walled sections considering the warping degree of freedom (DOF) and the twisting effects along with the transverse shear deformations. Additionally, a two-dimensional (2D) finite-element cross section analysis method employing the constant strain triangle (CST) element is developed to calculate the section properties for arbitrary cross sections, including the Wagner and the shear coefficients. The proposed method is implemented in the educational structural analysis software MASTAN2 and verified through two sets of examples. [ABSTRACT FROM AUTHOR]

In the evolving field of electric power transmission networks, high-voltage direct current (HVDC) transmission has garnered attention for its efficacy in long-distance power delivery. However, HVDC systems are susceptible to corona discharges, which generate ions that disrupt the electric field distribution and pose safety concerns. To address these challenges, this study introduces new calculation techniques for predicting the electric field and ion current density around HVDC transmission lines using the finite-element method. The onset fields for the corona discharge were established at 14 and 13 kV/cm for positive and negative ions, respectively. Three novel techniques—average (A), cosine (C), and average–cosine combination (AC)—were introduced for continuous charge distribution. Additionally, an enhancement factor $\beta$ was incorporated to reflect the various climatic conditions, enhancing the model’s adaptability. This approach streamlines the analysis by reducing the reliance on complex parameters such as conductor roughness coefficient and climate constants. The techniques were validated across four different bundle configurations of transmission lines, with the AC technique demonstrating superior accuracy in predicting the electric field and ion current density, affirming its robustness in diverse scenarios, including under wind conditions. This research marks a significant advancement in modeling electrical discharge phenomena in HVDC environments, providing a simplified yet precise tool for ensuring electrical safety.

Metal nanocages exhibit localized surface plasmon resonance that strongly absorbs and scatters light at specific wavelengths, making them potentially valuable for photothermal therapy and biological imaging applications. However, investigations on metal nanocages are still confined to high-cost and small-scale synthesis. The comprehensive analysis of optical properties and optimal size parameters of metal nanocages is rarely reported. This paper simulates the effects of materials (Ag, Au, and Cu), size parameters, refractive index of the surrounding medium, and orientation on the light absorption and scattering characteristics of the nanocages using the finite-element method and the size-dependent refractive-index model for metal nanoparticles. The results show that the Ag nanocages have excellent light absorption and scattering characteristics and respond significantly to the size parameters, while the refractive index and orientation of the surrounding medium have less effect on them. The Au nanocages also possess superior light absorption properties at specific incident wavelengths. This study also identified the optimized sizes of three metal nanocages at incident light wavelengths commonly used in biomedicine; it was also found that, under deep therapy conditions, Ag nanocages in particular exhibit the highest volume absorption and scattering coefficients of 0.708 nm−1 and 0.583 nm−1, respectively. These findings offer theoretical insights into preparing target nanocage particles for applications in photothermal therapy and biological imaging.

The real-time, full-field simulation of the tube hydroforming process is crucial for deformation monitoring and the timely prediction of defects. However, this is rather difficult for finite-element simulation due to its time-consuming nature. To overcome this drawback, in this paper, a surrogate model framework was proposed by integrating the finite-element method (FEM) and machine learning (ML), in which the basic methodology involved interrupting the computational workflow of the FEM and reassembling it with ML. Specifically, the displacement field, as the primary unknown quantity to be solved using the FEM, was mapped onto the displacement boundary conditions of the tube component with ML. To this end, the titanium tube material as well as the hydroforming process was investigated, and a fairly accurate FEM model was developed based on the CPB06 yield criterion coupled with a simplified Kim–Tuan hardening model. Numerous FEM simulations were performed by varying the loading conditions to generate the training database for ML. Then, a random forest algorithm was applied and trained to develop the surrogate model, in which the grid search method was employed to obtain the optimal combination of the hyperparameters. Sequentially, the principal strain, the effective strain/stress, as well as the wall thickness was derived according to continuum mechanics theories. Although further improvements were required in certain aspects, the developed FEM-ML surrogate model delivered extraordinary accuracy and instantaneity in reproducing multi-physical fields, especially the displacement field and wall-thickness distribution, manifesting its feasibility in the real-time, full-field simulation and monitoring of deformation states.

The objective of the investigation was to increase the effectiveness of damage detection in the stator of the squirrel-cage induction machine. The analysis aimed to enhance the operational trustworthiness of the squirrel-cage induction machine by employing nonintrusive diagnostic methods based on a current signal and modern artificial intelligence methods. The authors of the study introduced a diagnostic technique for identifying multiphase interturn short circuits of stator winding. These short circuits are one of the most common faults in induction machines. The proposed method focusses on deriving a diagnostic signal from the phase-current waveforms of the machine. The noninvasive nature of the diagnostic technique presented is attributed to the application of the field model of electromagnetic phenomena to determine the diagnostic signal. For this purpose, a field model of a squirrel-cage machine was developed. The waveforms of phase currents obtained from the field model were used as input into an elaborated machine failure neural classifier. A deep neural network was used to develop a neural classifier. The effectiveness of the developed classifier has been experimentally verified, and the obtained results have been presented, concluded, and discussed. The scientific novelty presented in the article is the presentation of research results on the use of a neural classifier to detect damage in all phases of the stator winding at an early stage of its appearance. The features of this type of damage are very difficult to observe in signal waveforms such as a phase current or torque. [ABSTRACT FROM AUTHOR]

The effect of distributed end-face and local axisymmetric operational non-stationary loads on sandwich cylindrical shell elements of rocket bodies has been studied. The action of the engine is characterized by longitudinal forces that have time-varying frequency and amplitude and are applied to the end of the shell. Additionally, we have simulated local axisymmetric external impulsive loads applied along the directrix of the cylindrical shell to the place of ribs and between them to imitate an explosion of an elongated cumulative instantaneous charge. Given the different material properties of the face layers, light core, and reinforcing ribs, it is advisable to employ the finite-element method. By finite-element modeling of the dynamics of the structure under operational loads, this research enables thoroughly investigating the effect of the light core and facilitates choosing the optimal locations for applying local axisymmetric impulsive loads. The numerical results obtained from real object simulations, based on the developed methodology, allow us to give recommendations for determining the optimal amount of cumulative charge necessary for separating the rocket's spent stage while maintaining its prescribed trajectory. [ABSTRACT FROM AUTHOR]

In this study, the effects in terms of electric stress of composite voltages on a high-voltage disconnector were investigated. The main purpose of this study is to determine and evaluate the effects of the conditions that may occur in real working conditions but out of the type tests. As for the disconnector model, one phase of a center-break disconnector was considered. In order to examine the effects of composite voltages on high-voltage disconnectors, a model is defined in the Comsol Multiphysics program. Different types of voltages such as operating voltage, 50 Hz test voltage, lightning impulse voltage, and composite voltage, were applied to the 170 kV disconnector model separately. After applying a composite voltage consisting of power frequency voltage and lightning impulse voltage to the disconnector, electric potential and electric field distributions were obtained. It has been observed that the maximum electric potential and the maximum electric field strength values on the disconnector are higher when composite voltage is applied than when non-composite voltage is applied to the disconnector. It is observed that the intensity of the electric field lines increases near the contacts of the current-carrying arm and the main contacts of the disconnector. [ABSTRACT FROM AUTHOR]

Many technical objects use the electromagnetic DC actuators, which, unlike AC actuators, are more reliable, simpler in terms of manufacturing technology and have greater wear resistance. The listed advantages are the reason for the significant use of DC actuators in various industries including application as drive mechanisms of electrical devices. The DC actuator as a part of any technical object almost always plays one of the main roles from the point of view of reliable operation of entire device. Therefore the question of studying the designs of actuators and their characteristics is a rather topical task. Three designs of forward-moving electromagnetic DC actuators with the same overall dimensions and winding data are studied. They differ in the shapes of the supporting surfaces of poles, in other words, the surfaces with flat, conical and cut-conical shapes. As established, the shape of the supporting surfaces of poles has a significant impact on the thrust characteristics of the actuator and depending on the length of air gap this effect has a different character. The patterns of magnetic field of the studied actuators with an attracted armature are constructed, and the nature of magnetic field distribution and magnetic flux density distribution in operated gap are evaluated. The nature of the influence of cutting angle on static thrust characteristic for actuators with conical and cut-conical pole shapes is studied too. References 21, table 1, figures 7. [ABSTRACT FROM AUTHOR]

This study aims to identify and evaluate the significance of the key design factors that impact the stability of Earth retaining wall anchor-supported structures during excavations in urban areas. Although there are many previous studies on the deformation of Earth retaining walls during excavation, there is a lack of verification studies that quantitatively examine the stability of various influencing factors such as wall, ground characteristics, and external influencing factors. To this end, finite-element analyses were conducted, and their results were compared and validated with field measurements. These comparisons demonstrated that the numerical modeling technique employed in this study effectively simulates the wall's behavior under excavation conditions. Subsequently, the impact of the main design factors, including ground properties, external conditions, and structural stiffness, on the behavior of the wall was quantitatively assessed by applying variation ratios. The findings indicate that the horizontal displacement of the wall, induced by excavation, is significantly dependent on the unit weight and shear strength of the soil. Conversely, the groundwater level location, surcharge load, and structural stiffness exhibit a relatively minor effect. Finally, the variability of the main design parameters was investigated, considering the specific ground layer where the wall is installed, revealing distinct influences of these variables across different ground layers. Consequently, it is expected that the importance of the influencing geotechnical factors will be selected and used for predicting the behavior of Earth retaining walls and actual design, which will help to efficient wall design. [ABSTRACT FROM AUTHOR]

Metro systems provide an efficient, convenient, and expeditious way to travel around crowded routes. Because these systems are established in cities, residential buildings close to metro viaducts are significantly affected by structure-borne noise (SBN). Although most previous studies developed SBN prediction with a focus on the accuracy and computational efficiency of a specific bridge type, only limited studies on parameters for the SBN on bridges were carried out. Thus, eliminating SBN is still a challenging task for both the design and operation phases of bridge design. Therefore, this study integrates simplified experiments with numerical analyses to evaluate the influential parameters on the structure-borne noise level (SBNL) for two types of bridge girders, that is, the double-box pre-stressed concrete girder and the double-box steel girder. The present study also proposes an optimization method for reducing the SBNL in the bridge design and operation phases and identifies the sources of SBN for these two types of bridges. In this paper, the solutions to mitigating SBN are first reviewed and briefly introduced. Theories associated with SBN are then derived and experimentally verified using a concrete or steel plate with a unit area. A hybrid evaluation method is developed to integrate transient finite-element simulation with experimental results, and the main sources (e.g., plate thickness, train speed, fastener stiffness, and track irregularity) that induce SBN are examined by this hybrid method. Consequently, the approach to resolving the SBN problem can be optimally determined. As demonstrated in the results from the hybrid evaluation method, the track condition dominates the SBNL for both types of bridges, and the relationship between train speed and plate eigenfrequency should be carefully investigated to avoid the effect of plate resonance. The pre-stressed concrete box girder is the recommended bridge type for use in urban areas from the viewpoint of minimizing the SBNL. [ABSTRACT FROM AUTHOR]

The split Hopkinson pressure bar (SHPB) is a machine used for obtaining dynamic material properties at high strain rates of 102–104 s−1. In the SHPB test, the material properties obtained vary depending on the shape of the specimen. In other words, it is important to understand the behavior of the specimen when selecting the specimen dimensions. However, specific standards, such as the size of specimens and bars for the SHPB, have not yet been established. This study investigates the effect of changing the specimen diameter on strain and stress results. Comparison and verification with experimental results were performed using the LS-DYNA program. Specimens are cylindrical titanium grade 1. The specifications of bars and length ( L ) of the specimens were not changed. The results revealed that the reflected ratio increased, and the transmitted ratio decreased as the area of the specimen decreased. The ratios of these strains are affected by impedance ( Z = ρ A C ). The area reduction of specimens under the same conditions made it possible to obtain dynamic properties at a higher strain rate. It was shown that the impedance relationship and strain rate can be altered by varying the diameter of the specimen without changing the dimensions or material of the bar itself. [ABSTRACT FROM AUTHOR]

Although nondestructive ultrasonic technologies have been applied in laboratory and field tests in the field of heritage conservation, few studies have quantified the relationship among the real microstructures, micromechanical properties, and macroscopic acoustic responses of earthen-site soils. This paper develops a micromechanics-based multiscale model for quantitatively exploring the ultrasonic propagation characteristics of elastic waves in untreated and consolidated earthen-site soils. Scanning electron microscope images and image processing technology are integrated into the finite-element simulation. The effects of microstructure and wave features on the acoustic characteristics of soils are quantitatively investigated under pulsive loading. The simulation results of untreated and consolidated soils are efficiently compared to ultrasonic test data. It is demonstrated that the integration of microstructure image processing and multiscale modeling can predict the ultrasonic pulse velocity well, which improves the accuracy of laboratory testing and field monitoring and better serves the evaluation and implementation of engineering practice in the field of heritage conservation. [ABSTRACT FROM AUTHOR]

Introduction: Crystalline lens overshooting refers to a situation in which the lens momentarily shifts too much from its typical location immediately after stopping the rotational movement of the eye globe. This movement can be observed using an optical technique called Purkinje imaging.Methods: In this work, an experimental setup was designed to reproduce this effect ex vivo using a fresh porcine eye. The sample was rotated 90° around its centroid using a high-velocity rotation stage, and the Purkinje image sequences were recorded, allowing us to quantify the overshooting effect. The numerical part of the study consisted of developing a computational model of the eye, based on the finite element method, that allowed us to understand the biomechanical behavior of the different tissues in this dynamic scenario. A 2D fluid–structure interaction model of the porcine eye globe, considering both the solid parts and humors, was created to reproduce the experimental outcomes.Results: Outputs of the simulation were analyzed using an optical simulation software package to assess whether the mechanical model behaves optically like the real ex vivo eye. The simulation predicted the experimental results by carefully adjusting the mechanical properties of the zonular fibers and the damping factor.Conclusion: This study effectively demonstrates the importance of characterizing the dynamic mechanical properties of the eye tissues to properly comprehend and predict the overshooting effect.

Introduction. A distinctive feature of CLT panels is the cross arrangement of planks (lamellae) in different layers of the board. Due to the anisotropy of wood, this design allows for high strength and stiffness in different directions of stress action, which has made this material one of the most promising to be studied in recent decades. This article examines the influence of the thickness of transverse and longitudinal layers in five-layer slabs of cross-glued timber boards, or CLT panels, on the deformation and distribution of the resulting normal and tangential stresses. The relevance of the work is conditioned by the necessity of obtaining calculated data to analyze changes in the strength characteristics of boards with different variations in the thickness of longitudinal and transverse layers in order to choose the most effective configuration of the board.Materials and methods. The studies were carried out by numerical methods using SCAD+ PC using FEM (Finite element method). At the same time, the three-dimensional finite elements are parallelepipeds. The design scheme is defined as a general-type system, whose deformations and its main unknowns are represented by linear displacements of nodal points along the X, Y, Z axes and rotations around these axes. As a design structure, a five-layer slab with cross-directed layers was chosen in such a way that the outer (1, 5) and central inner (3) layers are longitudinal, and the remaining inner (2, 4) are transverse. The simplified design scheme is a pivotally supported beam.Results. The results of the study and calculations made using SCAD+ were applied to make tables and graphs showing dependence of deflection, distribution of normal and tangential stresses on the thickness of transverse and longitudinal layers of the board.Conclusions. The obtained data allow us to evaluate the influence of thickness on deformability and stress distribution in five-layer CLT panels. The significance of the conducted research is in the expansion of scientific and technical knowledge base in the field of wooden structures.

In this research, we present the results of analyzing the technical feasibility of an old invention by Henry Muncaster from the perspective of mechanical engineering, specifically focusing on the resistance of materials. The invention is a two-cylinder steam engine with a parallel motion crosshead, for which plans were published in the Model Engineer magazine in 1957. This complex device, composed of 76 elements and lacking descriptive information, has been the subject of a recent article that illustrated its design through the engineering drawing discipline and a 3D CAD model. To provide reliable information and conduct a comprehensive study of its technical feasibility, an extensive linear static analysis was performed. This analysis considered two critical positions of the piston inside the cylinder: upper dead center and lower dead center. We determined the optimal range of working pressures necessary to achieve a safety factor within the optimal design range of two to four. The results include von Mises stresses, displacements, and safety factor distributions, confirming that the optimal working pressure range for steam intake is between 1.885 and 3.550 MPa. This ensures that the safety factor values remain between 2.01 and 3.78.

This article analyzes the mechanical behavior of a single-cylinder horizontal steam engine with a crosshead trunk guide designed by Henry Muncaster. This double-acting steam engine was incorporated as an engine in various means of locomotion, and its drawings were published in Model Engineer magazine in 1957. This historical invention, for which there is no detailed information about its operation, presents great complexity because of the large number of components (44) of which it consists, transforming the reciprocating movement into rotary movement. The research carried out consisted of carrying out a linear static analysis in two critical positions (lower dead center and upper dead center) and determining the optimal range of working pressures in order to achieve a safety factor located in the optimal design range with values between 2 and 4. This linear static analysis was carried out using the Stress Analysis module of the Autodesk Inventor Professional 2024 software, applying the finite-element method (FEM). The results obtained regarding the von Mises stresses, displacements, and safety factors confirm that the optimal range of working pressures (maximum admissible steam pressure during admission) is between the values of 0.165 and 0.320 MPa.

An electric motor mounting bracket is used in electric vehicles, especially hybrid ones using a parallel hybrid configuration. This study aims to analyze the strength and performance of the initial design and topology optimized design. This study uses the finite-element method (FEM) in the bracket design modeling by applying topology optimization. The topology optimization results show a mass reduction of 50% from the initial design mass. In the case of static loading, the results of optimized design 2 have a stress of 142.19 MPa and a safety factor of 3.09. While optimized design 1 has a stress of 313.8 MPa and a safety factor of 1.4. In terms of dynamic loading, the initial design, optimized design 1, and optimized design 2 have the first natural frequency, which is higher than the operating frequency of the electric motor, respectively, 100.49, 69.043, and 74.864 Hz. Optimized design 1 has the lowest natural frequency and the highest amplitude compared to the initial design, and optimized design 2 has lower damping characteristics. The study results conclude that optimized design 2 is superior in static and dynamic loading.

In order to solve the accurate calculation problem of spoke-type permanent magnet machines with multi-layer winding structure in the magnetic field, based on the two-dimensional subdomain analytical modeling idea, a magnetic density analytical calculation method considering the saturation effect at the rotor magnetic bridge and stator multi-layer winding structure is proposed. In this method, the magnetic vector potential calculation of multi-layer armature winding can be calculated by subdomain division in the stator slot. Then, the saturation effect at the spoke-type rotor core magnetic bridge is equivalent by using an equivalent air gap. To ensure the accuracy of calculation, the error check and cyclic iteration are applied in this method. The key contribution of this method is effectively solving the interior permanent magnet machines′ magnetic field calculation problem in the traditional subdomain modeling method due to the inability to consider the finite magnetic permeability of the core. Taking 8-pole 9-slot and 10-pole 12-slot permanent magnet machines as examples, finite element models with different winding structures are built to validate the validity of the proposed method. The results show that the analytical method achieves a reduction in the computation time while maintaining the calculation accuracy.

Abstract Introduction Long-term simulation of tooth movement is crucial for clear aligner (CA) treatment. This study aimed to investigate the effect of maxillary molar distalization with CA via an automatic staging simulation. Method A finite-element method (FEM) model of maxillary dentition, periodontal ligaments, attachments, and corresponding CA was established, and a prescribed 2-mm distalization with 0.1 mm each step of the second molar was simulated. The long-term tooth movement under orthodontic force was simulated with an iterative computation method. The morphologic changes of CA during staging were simulated with the thermal expansion method. Results Twenty steps of molar distalization were simulated. Significant distal tilting of the second molar was revealed, along with the proclination of anterior teeth, which caused the ‘reversed bow effect’. For the second molar, 4.63°distal tilting at the 20th step was revealed. The intrusion of the incisors and the second molar were 0.43 mm, 0.39 mm, and 0.45 mm, respectively, at step 20. All the anterior teeth showed a proclination of approximately 1.41°–2.01° at the 20th step. The expression rate of the designed distalization of the second molar was relatively low (approximately 68%) compared to the high efficacy of interdental space opening between molars with CA (approximately 89%). Conclusion A novel method of simulating long-term molar distalization with CA with FEM was developed. The FEM results suggested distal tilting of the second molar and the proclination of anterior teeth during the molar distalization.

This study aims to identify and evaluate the significance of the key design factors that impact the stability of Earth retaining wall anchor-supported structures during excavations in urban areas. Although there are many previous studies on the deformation of Earth retaining walls during excavation, there is a lack of verification studies that quantitatively examine the stability of various influencing factors such as wall, ground characteristics, and external influencing factors. To this end, finite-element analyses were conducted, and their results were compared and validated with field measurements. These comparisons demonstrated that the numerical modeling technique employed in this study effectively simulates the wall’s behavior under excavation conditions. Subsequently, the impact of the main design factors, including ground properties, external conditions, and structural stiffness, on the behavior of the wall was quantitatively assessed by applying variation ratios. The findings indicate that the horizontal displacement of the wall, induced by excavation, is significantly dependent on the unit weight and shear strength of the soil. Conversely, the groundwater level location, surcharge load, and structural stiffness exhibit a relatively minor effect. Finally, the variability of the main design parameters was investigated, considering the specific ground layer where the wall is installed, revealing distinct influences of these variables across different ground layers. Consequently, it is expected that the importance of the influencing geotechnical factors will be selected and used for predicting the behavior of Earth retaining walls and actual design, which will help to efficient wall design.

The permanent magnet vernier synchronous machine (PMVSM) has the characteristics of high torque density and high power density and has advantages in the field of low-speed and high-torque applications. The PMVSM utilizes rich harmonics for torque enhancement, but it can also cause an increase in radial electromagnetic force and vibration noise. In this paper, we take a 12-slot 10-pole PMVSM as an example to analyze the source of radial electromagnetic force, vibration and noise. The electromagnetic finite-element model and structural finite-element model of the PMVSM are established for calculation. Through the analysis and calculation of two-dimensional electromagnetic fields, the radial electromagnetic force distribution of the PMVSM is obtained. We derive the radial electromagnetic force formula of the PMVSM and verify the correctness of the formula through harmonic analysis of the radial electromagnetic force. The sources of radial electromagnetic forces at various orders and frequencies within the PMVSM are analyzed and summarized by coupling the radial electromagnetic force obtained from the electromagnetic finite-element model to the structural finite-element model and conducting electromagnetic vibration harmonic response analysis on the PMVSM. The measured acceleration spectrum of the prototype is compared with the finite-element method (FEM) results, verifying the correctness of the finite-element simulation results for electromagnetic vibration. [ABSTRACT FROM AUTHOR]

An assembled floor system is a main step in the industrialization of construction in civil engineering, where the stiffness and anti-crack properties under designed loads and its self-weight are the main concerns. This paper presents a new type of assembled integral composite floor system, which is composed of precast ribbed bottom slab, lightweight infills, cast-in-situ upper slab and joints. Through the couplers for squeezing and splicing of longitudinal bars, shear keys and cast-in-situ joints between the precast panels and cast-in-situ upper part, the whole hollow floor system could not only exhibit satisfactory mechanical performance, but also lower the self-weight and shorten the construction time. To study its flexural behaviors, a full-scale specimen sized 9.2 m × 9.2 m was designed and tested under static area load. With the load increased to the designed loads of Chinese design code GB50010-2010, mechanical performance (i.e., crack distribution, deformation and stress distribution) were analyzed. To further study its load-carrying capacity and working mechanism, an effective finite element model was established in ABAQUS and compared with experimental and simulation results. It was found that the deflection of the floor under the normal service load and the crack width met the needs of normal use, and the finite element model could serve as a reliable method for the load-carrying capacity calculation. [ABSTRACT FROM AUTHOR]

Deep excavations in soft clays often demand heavy shoring supports. Closely spaced struts are known to impede construction within an excavation, resulting in longer construction time. This paper presents a novel strut-free retaining wall constructed by deep cement mixing (DCM). A new U-shaped DCM system (UDCM) was developed to support a 6.5-m-deep, 16-m-wide excavation in newly reclaimed land. Field measurements involving inclinometers and surface movement markers were interpreted using a fully coupled three-dimensional finite-element model. Results indicated a rotational deformation mechanism in the DCM wall. The mechanism was triggered by stress relief and basal heave. Due to the rigidity of the UDCM, the occurrence of basal heave caused the DCM walls to deflect outward toward the retained side. Such a mechanism is not typical in conventional retaining wall systems in which lateral props are installed after certain depths of excavation. The present UDCM possesses a distinctive characteristic, which is the capability to implement and activate props prior to excavation. It also is unique in that basal heave is used to regulate the rotation of the wall, thereby limiting lateral displacements during an excavation. This study includes a design chart developed for the prediction of lateral displacements with varying treatment geometries. [ABSTRACT FROM AUTHOR]

The effect of distributed and localized axisymmetric impulsive loads on three-layer cylindrical shell elements of rocket airframes is studied. Localized axisymmetric impulsive external loads applied along the directrix of a cylindrical shell simulate an explosion of a superquick-action elongated shaped charge. Finite-element modeling of transient processes in such elements under such loads allows correct selection of the physical and mechanical parameters of cylindrical rocket airframes. A significant effect of the behavior of dynamic loads on the transient processes in three-layer cylindrical elements is demonstrated. [ABSTRACT FROM AUTHOR]

Phononic crystals are a kind of artificial acoustic metamaterial whose mass density and elastic modulus are periodically arranged. The precise and efficient design of phononic crystals with specific bandgap characteristics has attracted increasing attention in past decades. In this paper, an improved adaptive genetic algorithm is proposed for the reverse customization of two-dimensional phononic crystals designed to maximize the relative bandwidth at low frequencies. The energy band dispersion relation and transmission loss of the optimal structure are calculated by the finite-element method, and the effective wave-attenuation effect in the bandgap range is verified. This provides a solution for the custom-made design of acoustic metamaterials with excellent low-frequency bandgap sound insulation or other engineering applications. [ABSTRACT FROM AUTHOR]

This paper is the first that proposes an extended hybrid analytical method (HAM) based on a two-dimensional (2-D) coupling between the semi-analytical Maxwell-Fourier analysis and finite-element method (FEM) in polar coordinates. The proposed model is applied to any rotating electrical machines. The main objective of this paper is to establish the magnetic field solution in the whole machine by coupling an exact analytical model (AM), proposed for all regions having relative magnetic permeability equal to unity, with a FEM in ferromagnetic regions. The AM and FEM are coupled in both directions (r , θ) in the edge separating teeth regions and all its adjacent regions by applied boundary conditions (BCs). The developed HAM gives accurate results on the magnetic flux density distribution and the cogging torque whatever the operating conditions, the magnetic or geometric parameters. All results obtained give very satisfactory agreement with 2-D finite-element analysis (FEA). [ABSTRACT FROM AUTHOR]

Vibration analysis of bridges induced by train loads is a crucial aspect of railway design, particularly considering the complexity of vehicle components such as bogie-suspension systems. Consequently, railway engineers have endeavored to improve the computational efficiency and applicability of train models using the finite-element method. This paper introduces a toolbox implemented in ABAQUS through a user-defined element (UEL) subroutine, which incorporates the vehicle–bridge interaction (VBI) element theory. This toolbox effectively handles diverse vehicle–bridge interaction systems. In the proposed theory, the wheel-track contact force is derived based on the bridge response, eliminating the need for an iterative process and significantly reducing computational workload compared to classical physics-based analysis. The presented approach is validated through a moving sprung mass model and a moving rigid bar model. Furthermore, a case study is conducted on a three-dimensional finite-element model of a high-speed railway bridge in China, based on a design sketch, to showcase the capabilities of the developed scheme. The study demonstrates the practical application of the proposed methodology in analyzing vehicle–bridge structures with high complexity. [ABSTRACT FROM AUTHOR]

Abstract This work presents photonic crystal fibres made up of four hexagonal shape of four rings. Four structures have been designed and configured. The structures show improvement in optical properties consecutively to achieve the optimum configuration. The full vectorial finite-element method is adopted for this work. COMSOL Multiphysics is used for the simulation. The results show a birefringence of 1.308 × 10−2 at 1.55 µm and tuneable double zero dispersion at wavelengths of 0.99 µm and 1.8 µm for x-polarisation mode. Also, the chromatic dispersion of − 24.062 ps/km nm and nonlinear coefficient of 30.32 W−1 km−1 are obtained at a telecommunication wavelength of 1.55 µm. The proposed photonic crystal fibre can be beneficial in nonlinear and supercontinuum applications since photonic crystal fibres of double zero dispersion demonstrate higher power spectral densities than single zero dispersion.

Below the Arctic sea ice, under the right conditions, a flux of icy brine flows down into the sea. The icy brine has a much lower fusion point and is denser than normal seawater. As a result, it sinks while freezing everything around it, forming an ice channel called a brinicle (also known as ice stalactite). In this paper, we develop a mathematical model for this phenomenon, assuming cylindrical symmetry. The fluid is considered to be viscous and quasi-stationary. The heat and salt transport are weakly coupled to the fluid motion and are modelled with the corresponding conservation equations, accounting for diffusive and convective effects. Finite-element discretization is employed to solve the coupled system of partial differential equations. We find that the model can capture the general behaviour of the physical system and generate brinicle-like structures while also recovering dendrite composition, which is a physically expected feature aligned with previous experimental results. This represents, to our knowledge, the first complete model proposed that captures the global structure of the physical phenomenon even though it has some discrepancies, such as brine accumulation.

Triaxial tests are common laboratory methods to study the mechanical properties of soils. According to international practice, it allows determining the reliable strength and stiffness properties. This research paper describes the results of statistical analysis of the deformation parameters for clay soils obtained from triaxial tests. The research focused on clay deposits of the Quaternary, Jurassic and Carboniferous periods of diverse genesis. The results of 992 consolidated isotropic drained triaxial tests of clay soils in Russia (Moscow) and Belarus (Minsk) were analysed. More than 50% of the tests were carried out under unloading/reloading conditions. As a result, empirical equations enabling evaluation of the effects of physical properties and stress state on stiffness of clay soils with different age and genesis were proposed. Comparison of accomplished tests of Quaternary and Jurassic soils from Thailand, Europe and the USA showed that stiffness for overconsolidated soils is in the same range as soils from Moscow and Minsk sites. The performed studies revealed the values of the Hardening soil model m-parameter depending on soil forming factors and its preconsolidation degree. In overconsolidated soils, values of the m-parameter are on average twice less than in normally consolidated or lightly overconsolidated soils. Proposed equations can be applied for preliminary estimation of the stiffness parameters for finite element method calculation, as well as used in geotechnical models that allow variability, horizontal and vertical distribution of stiffness to be taken into account. In general, geotechnical engineers may utilize the obtained results by applying them to design of complex soil models.

The finite-element (FE) method for three-dimensional (3D) airborne electromagnetic (AEM) modeling can flexibly simulate complex geological structures at high accuracy. However, it has low efficiency and high computational requirements. To solve these problems, one needs to generate meshes more reasonably. In view of this, we develop an adaptive octree meshing scheme for frequency-domain AEM modeling. The octree meshes have the characteristics of regularity and flexibility, while the adaptive algorithm can effectively refine the mesh locally. In our adaptive mesh generation, the posterior errors and weighted coefficients are used to construct the final weighted posterior errors. We verify the accuracy of our method by comparing its results with semi-analytical solutions for a half-space model. Furthermore, we use the spectral-element (SE) method and our method to calculate EM responses for an abnormal block model and compare their computational costs. The results show that our adaptive scheme has obviously technical advantages over SE method for AEM modeling with multiple frequencies and multiple survey stations. Finally, we calculate a model with complex geological structures to verify the feasibility of our algorithm in complex geological circumstances. [ABSTRACT FROM AUTHOR]

Introduction: Long-term simulation of tooth movement is crucial for clear aligner (CA) treatment. This study aimed to investigate the effect of maxillary molar distalization with CA via an automatic staging simulation. Method: A finite-element method (FEM) model of maxillary dentition, periodontal ligaments, attachments, and corresponding CA was established, and a prescribed 2-mm distalization with 0.1 mm each step of the second molar was simulated. The long-term tooth movement under orthodontic force was simulated with an iterative computation method. The morphologic changes of CA during staging were simulated with the thermal expansion method. Results: Twenty steps of molar distalization were simulated. Significant distal tilting of the second molar was revealed, along with the proclination of anterior teeth, which caused the 'reversed bow effect'. For the second molar, 4.63°distal tilting at the 20th step was revealed. The intrusion of the incisors and the second molar were 0.43 mm, 0.39 mm, and 0.45 mm, respectively, at step 20. All the anterior teeth showed a proclination of approximately 1.41°–2.01° at the 20th step. The expression rate of the designed distalization of the second molar was relatively low (approximately 68%) compared to the high efficacy of interdental space opening between molars with CA (approximately 89%). Conclusion: A novel method of simulating long-term molar distalization with CA with FEM was developed. The FEM results suggested distal tilting of the second molar and the proclination of anterior teeth during the molar distalization. [ABSTRACT FROM AUTHOR]

High long-term stress on the plantar fascia (PF) is the main cause of plantar fasciitis. Changes in the midsole hardness (MH) of running shoes are an important factor leading to the alteration of the PF. This study aims to establish a finite-element (FE) model of the foot–shoe, and investigates the effects of midsole hardness on PF stress and strain. The FE foot–shoe model was built in ANSYS using computed-tomography imaging data. Static structural analysis was used to simulate the moment of running push and stretch. Plantar stress and strain under different MH levels were quantitatively analyzed. A complete and valid 3D FE model was established. With an increase in MH from 10 to 50 Shore A, the overall stress and strain of the PF were decreased by approximately 1.62%, and the metatarsophalangeal (MTP) joint flexion angle was decreased by approximately 26.2%. The height of the arch descent decreased by approximately 24.7%, but the peak pressure of the outsole increased by approximately 26.6%. The established model in this study was effective. For running shoes, increasing the MH reduces the stress and strain of PF, but also imposes a higher load on the foot. [ABSTRACT FROM AUTHOR]

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The transmitting and receiving coils used in wireless power transfer (WPT) systems in electric vehicles (EVs) have a larger air gap (~300 mm) and higher transmission power (kW) than those in typical WPT systems used in electrical appliances. However, this could weaken the magnetic field, reduce transfer efficiency, and lead to a public concern regarding potential adverse health effects related to electromagnetic field (EMF) exposure. Therefore, the assessment of compliance with product safety standards, based on international exposure guidelines such as the International Commission on Non-Ionizing Radiation Protection (ICNIRP), is crucial. This study uses the finite element method to analyze a commonly used core-less and core-based WPT system using a composite core material in EVs and scalar potential finite difference method for assessment of human protection. Based on the computational results, two core structures using different types of intermediate insert blocks were analyzed to reduce external magnetic fields and mitigate the human EMF exposure. The WPT system with a core structure improved the transfer efficiency by 34% for a 300 mm air gap over the core-less system. Moreover, this effectively reduced magnetic field leakage by 91.6% and induced electric field by 98.3%, resulting in the reduction of induced electric field in anatomical human body model. The results demonstrated that a WPT system with a composite core can simultaneously improve the transfer efficiency and protect humans from EMF exposure.

Abstract The generalized Schwarz algorithm for a class of elliptic quasi-variational inequalities related to impulse control problems is studied in this paper. The principal result is to prove the error estimate in L ∞ $L^{\infty}$ -norm for m subdomains with overlapping nonmatching grids. This approach combines the geometrical convergence and the uniform convergence.

Background Highly consistent cardiac ablation outcomes through radiofrequency catheter ablation (RFCA) under pulsatile and constant flow profiles (PP&CP) of intracardiac blood were previously indicated by computer modeling, with simplified geometry and lossless receipt of inflow for ablation catheters. This study aimed to further investigate the effects of intracardiac blood pulsatility in an anatomy-based atrium model.Methods Four pulmonary veins were blood inflows at 10 mm Hg. The mitral valve was the outflow, with PP based on pulsatile velocity curve from clinical measurements, and CP was obtained by averaging the velocity curve under PP over an ablation time of 30 s. A numerical comparison between ablation results under PP and CP, without experimental validation, was performed.Results Temperature fluctuations persisted in mid-myocardium, and most clearly in blood and endocardium under PP. At a constant power of 20 W, marked differences in ablation outcome between PP and CP occurred in the middle of unilateral pulmonary veins and the posterior wall of the left atrium (LA) where the blood velocities were significantly decreased under CP. The mid-myocardial, blood and endocardial temperatures, as well as the effective lesion volume at the former position, were decreased by 4.1%, 15%, 13.6%, and 13.8%, respectively under PP. The extents for the latter position were 11%, 22%, 22.5%, and 55.6%, respectively.Conclusion Intracardiac flow pulsatility causes a greater reduction in blood and endocardial temperatures at ablation sites away from the main bloodstream, effective cooling of which is more likely to rely on blood velocities approaching peak PP values.

Geometrically nonlinear analysis is required for resolving issues such as loading causes failure and structure buckling analysis. Although numerical methods are recommended for estimating the exact solution, they lack the necessary convergence in the presence of bifurcation points, making it challenging to find the equilibrium path using these methods. Thus, the modified energy method is employed instead of the numerical method, frequently used to solve quasi-static problems with nonlinear nature and bifurcation points. The ultimate goal of this study is to determine the critical load of structures through the modified energy method rather than other methods in which the relationship between force, displacement, and constraint is used to solve the problem. This study first describes the energy method for this type of problem and then details its computational steps progressively. This method yields numerical results when applied to numerical examples such as truss and frame structures and coded in MATLAB software. These findings are compared to the analytical results. The energy method is more precise than the alternative methods and superior to the Newton–Raphson method at crossing the load–displacement curve’s bifurcation points.