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In this work, fringing effect is studied on planar transformers for various frequencies, air gap lengths, core materials and core geometries to aid engineers in choosing the best transformer design with least fringing losses. Using finite element modelling, fringing losses were analysed for four different core geometries, namely EE, EI, ER and ETD, with varying core widths to estimate a generalized fringing losses equation. Emerging core materials like amorphous and nanocrystalline materials were analysed in addition to the common ferrite material for the core of the transformer. Simulations were performed for frequencies ranging from 50 to 400 kHz and air gap lengths varying from 0.05 mm to 0.25 mm. Using curve fitting, an equation was developed to estimate fringing losses. Fringing losses of a planar transformer were found to be directly dependent on its frequency, magnetic flux density, air gap length and core width. The fundamental difference of the proposed equation from the traditional fringing losses formula is that fringing losses were found to be proportional to the square of the frequency instead of the first power of frequency. Fringing losses were also calculated with the traditional formula, to analyse the improvement obtained with the proposed finite element modelling-based equation. It was observed that the proposed formula gave fringing losses results with a minimal error of about 9% for a range of lower and higher frequencies, whereas the traditional formula accounted for about 45% error for higher frequencies and around 11% error for lower frequencies. [ABSTRACT FROM AUTHOR]

This research aimed to assess the stress distribution in lower premolars that were obturated with BioRoot RCS or AH Plus, with or without gutta percha (GP), and subjected to vertical and oblique forces. One 3D geometric model of a mandibular second premolar was created using SolidWorks software. Eight different scenarios representing different root canal filling techniques, single cone technique with GP and bulk technique with sealer only with occlusal load directions were simulated as follows: Model 1 (BioRoot RCS sealer and GP under vertical load [VL]), Model 2 (BioRoot RCS sealer and GP under oblique load [OL]), Model 3 (AH Plus sealer with GP under VL), Model 4 (AH Plus sealer with GP under OL), Model 5 (BioRoot RCS sealer in bulk under VL), Model 6 (BioRoot RCS in bulk under OL), Model 7 (AH Plus sealer in bulk under VL), and Model 8 (AH Plus sealer in bulk under OL). A static load of 200 N was applied at three occlusal contact points, with a 45° angle from lingual to buccal. The von Mises stresses in root dentin were higher in cases where AH Plus was used compared to BioRoot RCS. Furthermore, shifting the load to an oblique direction resulted in increased stress levels. Replacing GP with sealer material had no effect on the dentin maximum von Mises stress in BioRoot RCS cases. Presence of a core material resulted in lower stress in dentin for AH Plus cases, however, it did not affect the stress levels in dentin for cases filled with BioRoot RCS. Stress distribution in the dentin under oblique direction was higher regardless of sealer or technique used. [ABSTRACT FROM AUTHOR]

The present research investigates optimizing the impact resistance of functionally graded sandwich structures using experimental and numerical approaches. The low-velocity impact (LVI) responses of functionally graded sandwich composite (FGSC) with different configurations with skin material jute/rubber/jute (JRJ) and core material having epoxy and sea sand by volume fraction of sea sand at 0%, 10%, 20%, and 30%. Sandwich structures were impacted with LVI (5.89, 10.92, and 15.18 m/s), with the impactor dropped from heights of 0.5, 1, and 1.5 m with precompressed spring loads. FGSC samples are considered a deformable body, and the impactor is modeled as a rigid body using commercially accessible dynamic explicit software. The burnout test and weight method were used to test the core's gradience; both methods' results substantially matched, and the variance in gradation could be observed. The proposed sandwich structure characteristics are examined by energy absorption, peak force, energy loss percentage, and coefficient of restitution. Results showed that SC30S provides greater energy absorption and superior damage resistance when tested on LVI. To evaluate the accuracy of experimental findings in predicting the indentation behavior of the sandwich structure, the finite element analysis was used to compare with the experimental results. According to the examination of these proposed FGSC overall performance, they could potentially be employed as sacrificial materials for LVI applications like claddings to shield major structural components. The systematic approach used in this work serves as a standard for choosing and using FGSC effectively for LVI applications. Highlights • Low-velocity impact behavior of sandwich structures was investigated. • Combining flexible skin and epoxy core enhances energy absorption. • Based on impact energy levels, impact damage areas were determined. • Examined sandwich structure advantages in structural and aerospace uses. • In terms of time and cost, the numerical analysis method would be useful. [ABSTRACT FROM AUTHOR]

For photothermal therapy of cancer, it is necessary to find Ag @TiO2 core-shell nanoparticles that can freely tune the resonance wavelength within the near-infrared biological window. In this paper, the finite element method and the size-dependent refractive index of metal nanoparticles were used to theoretically investigate the effects of the core material, core length, core aspect ratio, shell thickness, refractive index of the surrounding medium, and the particle orientation on the light absorption properties of Ag@TiO2 core-shell nanospheroid and nanorod. The calculations show that the position and intensity of the light absorption resonance peaks can be freely tuned within the first and second biological windows by changing the above-mentioned parameters. Two laser wavelengths commonly used in photothermal therapy, 808 nm (first biological window) and 1064 nm (second biological window), were selected to optimize the core length and aspect ratio of Ag@TiO2 core-shell nanospheroid and nanorod. It was found that the optimized Ag@TiO2 core-shell nanospheroid has a stronger light absorption capacity at the laser wavelengths of 808 nm and 1064 nm. The optimized Ag@TiO2 core-shell nanoparticles can be used as ideal therapeutic agents in photothermal therapy. [ABSTRACT FROM AUTHOR]

In order to achieve low refractive index detection in biomedical and material chemistry, a D-type microstructured optical fiber (MOF) sensor based on surface plasmon resonance (SPR) is proposed in this paper. The sensor uses gold nanofilm as sensing material between the core of the fiber and the plasma on the surface, and is coated at the open ring. Parametric analysis of the open-ring diameter, air hole diameter, and thickness of the gold nanofilm of the sensor was carried out by finite element method. The simulation results show that the sensor has a wavelength sensitivity of up to 10,900 nm/RIU, the refractive index range of 1.20–1.34, optimal resolution of 9.17 × 10−6 RIU, and a decent figure of merit (FOM) is 46.2 RIU−1. The proposed MOF-SPR sensor has high wavelength sensitivity and low resolution in a similar detection range compared to existing studies. The sensor is capable of detecting not only low refractive index substances, such as liquid medical oxygen with a refractive index of 1.22 and sevoflurane with a refractive index of 1.27, but also conventional refractive index substances such as water contamination with a refractive index near 1.33, providing a wide detection range. Therefore, the sensor is competitive in the detection of some low refractive index material detection fields. [ABSTRACT FROM AUTHOR]

• Homogenisation effects on the vibrations of mutlilayered microbeams with an AFG core and metal foam face layers are studied. • Differences in natural frequencies between homogenisation schemes vary with varying power gradation constant. • Higher length scale parameter leads to larger differences in natural frequencies between homogenisation schemes. • Relationship between the rotational natural frequency and the functionally graded core thickness is not linear. This study assesses the significance of homogenisation models in theoretically analysing the vibrations of three-layered microbeams with a core composed of axially functionally graded (AFG) material and with upper and lower face layers composed of metal foam material, especially when the third order shear deformation beam theory and the modified couple stress theory are used. The material of the core is assumed to vary following a power gradation profile. The range of homogenisation schemes, including the Voigt model, Reuss model, Voigt-Reuss-Hill model, Tamura model, Mori-Tanaka model, lower and upper bounds of Hashin-Shtrikman, and the local representative volume element (LRVE) model, are utilised to approximate the material properties of the AFG core. The upper and lower layers of metal foams are modelled using the closed-cell and open-cell solid porosity models. The coupled motion equations are solved for the natural frequencies of the system for the transverse, rotational and axial directions. A software-based finite element analysis (FEA) study of two simplified macrobeam systems was undertaken and the agreement between the FEA and numerical results, using the presented theoretical method, is found to be excellent. It has been confirmed that the homogenisation schemes have a notable effect on the mechanical properties of the AFG core, and hence on the coupled translational-rotational motion's natural frequencies. The largest difference in natural frequencies between different homogenisation schemes is found with a power gradation constant of approximately 0.53. A larger disparity of natural frequencies between different homogenisation methods was seen with an increase in the thickness of the AFG core and the microbeam's length-scale parameter of multilayered porous microbeam. The results of this study highlight the significance of homogenisation scheme employed when investigating the vibrations of a multilayered microbeam with an AFG core and metal foam porous face layers. [ABSTRACT FROM AUTHOR]

In recent years, researchers have shown interest in blocking low-frequency vibrations with the aid of metamaterials due to their inherent wave-filtering properties. However, proposing a practical metamaterial layout remains a challenge, taking into consideration the size, shape, and availability of metamaterial components. This study proposes a new configuration that can increase the range of the attenuation frequency. The configuration focuses on the capability of graded metamaterials in filtering a wide range of wave frequencies that can be generated by low-amplitude waves. To find the best configuration with the widest bandgap, square periodic sections using different materials including steel, rubber, concrete, tungsten, and carbon fiber-reinforced polymer were considered. Unit cells with two layers of materials were examined numerically to determine the attenuation zones and the effect of material properties and core size on the bandgap width and frequency range. Furthermore, the performance of the unit cells in a soil medium under the low-amplitude low-frequency surface and bulk waves is evaluated in the frequency domain using finite element analysis, in which the metamaterial is embedded periodically in a soil medium with different configurations, including a graded distribution. The results show that having an array of unit cells spaced periodically can decrease the transmission of the wave to the protected zone located after the array, and the application of grading can increase the attenuation zones to filter frequencies as low as 4.5 Hz and up to 29 Hz. [ABSTRACT FROM AUTHOR]

Panels made using honeycomb sandwich technique can help aerospace manufacturers maintain weight and fulfill certain strength requirements. Rigidity, stress absorption, fatigue resistance, and resistance to weather, chemicals, fire and isolation are some of the key benefits of honeycomb panels. Due to mechanical and acoustical requirements for high strength and weight target, it is common to select a sandwich design with a cheap and recyclable core material. Among other things, honeycomb sandwich structures are used in ship hulls, automobiles and civil constructions. Usage of these designs is the best way to obtain high strength and title material utilization. In this paper, the designs of hexagonal and square honeycomb constructions are evaluated for the most favorable structural outcomes. A honeycomb panel was produced using SolidWorks software. The proposed model was subjected to structural analysis using LS-DYNA software for four distinct kinds of materials: copper, steel, titanium and aluminum. Finally, the simulation results are presented and discussed. [ABSTRACT FROM AUTHOR]

In recent time, magnetically controlled shunt reactors are widely used in solving power quality problems. These reactors are designed to reduce system reactive power, control high super/special high voltage grid voltage, suppress power frequency, regulate overvoltage, eliminate generator excitation, dynamically compensate transmission line power charge, suppress secondary arc current, suppress system resonance. By using suitably designed silica plate core reactors at the input of the frequency converters in the electrical distribution system, the level of harmonic currents drawn from the electrical power distribution system can be reduced to certain rates. The core material, the air-gapped nature of the reactor core, and the sizing of the reactor have a great influence on the harmonic level of the current and its ability to reduce losses in the reactor. In this study, three reactors with different core materials and different air gap gaps are designed for a certain voltage value. Parametric analysis of the reactors designed to see the changes in inductance values depending on the load level has been made both theoretically and experimentally and using the Finite Element Method. As a result of the analysis, the inductance stability, losses and compliance of the reactors with the standards are presented. The reactor's magnetic circuit is modeled with ANSYS@Maxwell, realizing a solution based on this method. The magnetic circuit is simulated to see the behavior of the reactor. In addition, real-time verification of the designed alternating current reactor has been made. Optimum design was obtained by using different core materials and different core air-gaped tested experimentally. The effect of the air gap distance in the core on the magnetic field and inductance value was also obtained. [ABSTRACT FROM AUTHOR]

The explosion products, such as shock waves, fragments and heat energy formed by explosion, act on the plate structure, which may cause structural damage, material failure and even phase transformation of material. In this paper, the damage mechanism and protective effect of near-field blast load on sandwich structure based on foam-nickel core material were studied. Firstly, the near-field explosion test was conducted to investigate the blast response of the foam-nickel sandwich structure subjected to blast shock from 8701 explosive at near-field position. The deformation characteristics and stress history of the sandwich structure on the acting location of blast load were carefully investigated via experimental methods. A finite element model of near-field explosion was established for effective numerical modelling of the dynamic behaviour of the sandwich structure using the explicit dynamics software ANSYS/LS-DYNA for more comprehensive investigations of the blast shock response of the sandwich structure. The finite element model is reasonable and validated by mesh independence verification and comparing the simulated response behaviour to that from the experimental results for the sandwich structure subjected to near-field blast load. On this basis, the damage mechanism and protection effect of the near-field explosion impact on foam-nickel cores with different density and porosity are simulated more systematically. The investigated results from the experiments and a series of numerical simulations show the large deformation effect due to the extensive energy absorption, which suggests that the sandwich structure based on foam-nickel core material may be expected to become a new choice of protective structure under near-field blast load. [ABSTRACT FROM AUTHOR]

In this paper, a new optimization design strategy is explored to achieve a rapid design of lightweight structures for unmanned aerial vehicles (UAVs) using honeycomb sandwich panels. Based on the existing performance equivalent method of honeycomb core material, an effective mechanical property homogenization model of honeycomb material is proposed and applied to finite element analysis. A finite element model is established to analyze the mechanical response of honeycomb sandwich panels under different bending loads, and the rationality of the model is verified by mechanical tests. The error between the simulation results and the experimental results is about 10%. Based on the variable density method and rational approximation of material properties interpolation method, a topology optimization model with the minimum structural flexibility as the objective is constructed. By comparing with the experiment-based design scheme, it is found that the optimized design scheme has a more reasonable structure and better performance. The optimized design can effectively reduce the structural weight and improve the load transfer path while ensuring structural stiffness. In this way, the influence of stress concentration and large deformation on the structure is avoided, which is of great significance for the design of UAV structures. [ABSTRACT FROM AUTHOR]

High-frequency transformer core materials are used in power converter applications due to high efficiency performance. Their volume and weight can be reduced when higher operating frequencies are used but at the expense of an increase in core material losses. Some studies analyzed transformer core material performance by using finite element method (FEM) analysis, while others used an experimental model. This study proposes an experimental approach to compare the high-frequency transformer efficiency performance of different core material types. In this way, newly produced core material performance can be rapidly analyzed by comparing it against a known core material type, thereby resulting in the fast identification of improved core material design. This empirical approach makes use of a standard half-bridge inverter topology to enable an analysis of high-frequency transformer core material efficiency performance. Actual voltage and current measurements are used to determine the efficiency and output power performance throughout a specified constant current load range at different switching frequencies. Initially commercial standard polycrystalline or ferrite E-core materials were used to validate the characterization jig performance measured curve trends. The usefulness of the jig is then demonstrated by comparatively analyzing and then verifying the expected performance difference between polycrystalline and nanocrystalline toroidal core materials. [ABSTRACT FROM AUTHOR]

Early childhood caries (ECC) involve extensive coronal tooth structure loss, and tooth reconstruction remains highly challenging. To fulfill preclinical assessment, the present study investigated the biomechanics of non-restorable crownless primary molars that were restored by stainless steel crowns (SSC) using different composite core build-up materials. Computer-aided design-integrated 3D finite element and modified Goodman fatigue analyses were performed to determine stress distribution, risk of failure, fatigue life and dentine–material interfacial strength for the restored crownless primary molars. A dual-cured resin composite (MultiCore Flow), a light-cured bulk-fill resin composite (Filtek Bulk Fill posterior), a resin-modified glass-ionomer cement (Fuji II LC) and a nano-filled resin-modified glass-ionomer cement (NRMGIC; Ketac N100) were used as core build-up composite materials in the simulated models. The finite element analysis showed that types of core build-up materials affected the maximum von Mises stress only in the core materials (p-value = 0.0339). NRMGIC demonstrated the lowest von Mises stresses and revealed the highest minimum safety factor. The weakest sites were along the central grooves regardless of type of material, and the ratio of shear bond strength to maximum shear stress at the core–dentine interface of the NRMGIC group was lowest among the tested composite cores. However, all groups provided lifetime longevity from the fatigue analysis. In conclusion, core build-up materials differentially influenced the von Mises stress (magnitude and distribution) and the safety factor in crownless primary molars restored with core-supported SSC. However, all materials and the remaining dentine of crownless primary molars provided lifetime longevity. The reconstruction by core-supported SSC, as an alternative to tooth extraction, may successfully restore non-restorable crownless primary molars without unfavorable failures throughout their lifespan. Further clinical studies are required to evaluate the clinical performance and suitability of this proposed method. [ABSTRACT FROM AUTHOR]

Linear variable differential transformer (LVDT) is a commonly used linear displacement sensor because of its good measurement characteristics. When using laminated ferromagnetic cores in LVDTs, it is very important to take eddy currents into the account during design phase of the sensor. Particularity of the open-type core means that the eddy currents induced by the stray magnetic flux that flow in large loops tangential to the lamination surfaces take on significant values. Due to the open-type core a typical LVDT has, depending on the core material, it is, therefore, very important to take eddy currents into the account when designing the sensor. This paper's goal is to present a methodology for calculating LVDT eddy current losses that can be applied to LVDT design in order to optimize the dimensions and help with selection of materials of the LVDTs, in order to achieve the highest measurement accuracy. Presented approach using an A τ A -formulation with elimination of redundant degrees of freedom exhibits rapid convergence. In order to calculate the relationship between eddy current losses and core displacement, frequency, and material characteristics, a number of 3D finite element method (FEM) simulations was performed. Analysis of the obtained results using presented methodology for eddy current losses calculation in LVDTs enables the designer optimize the design of the LVDT. [ABSTRACT FROM AUTHOR]

Switched reluctance generator (SRG) has become the key focus of research for its usage in wind power generation. The sizing and performance of SRG depend on the core material used for the stator and rotor. This paper analyses the impact of the magnetic loading of different core materials on the performance of SRG in terms of self-inductance, torque, iron losses, ohmic losses, and generated voltage. 1 kW SRG with different pole configuration 8/6 SRG and 12/8 SRG for the wind speed of 3 m/s to 6 m/s has been designed. Static and dynamic analyses using the finite element analysis (FEA) were carried out for analytically designed 1 kW SRG with different core materials with the same lamination thickness. Prototypes of 8/6 SRG and 12/8 SRG are fabricated. The output of simulation results has been validated by experimental measurements. [ABSTRACT FROM AUTHOR]

This study presents a comparative simulation of electrical steels with different grain orientations in three-phase dry-type power distribution transformers. Electrical steels modeled as three-phase transformer cores are analyzed and compared. In this context, time-dependent simulations of three-dimensional transformer models were performed using the coupling method based on finite element analysis to determine core losses and thermal behavior differences. This study reveals the effects of different grades of core materials on time-dependent core temperature depend on power losses and magnetic flux density. For this purpose, a 100 kVA three-strand three-phase dry-type transformer was used to simulate and prove the concept, and the simulation results were compared. As a result, according to mathematical calculations, core losses for M3, M4, and M5 were 298 W, 340 W, and 402 W, respectively, while the error rates between them were found to be 2.95%, 1.1%, and 5.5%, with the simulation results. The maximum temperature values obtained as a result of the time-dependent thermal analysis according to these loss values are 70.71°C, 70.724°C, and 80.619°C, respectively. These results show how important the material selection is in terms of design, efficiency, and transformer life. [ABSTRACT FROM AUTHOR]

Honeycomb materials are commonly used as cores for sandwich panels. While empirical evidence exists showing that the transverse shear strength of a honeycomb core is affected by its thickness, the accuracy of empirical guidelines and the reasons for the changes in strength are not well understood. Four-point flexural testing of sandwich beams and a detailed cellular finite element model are used to investigate transverse shear failure of Nomex™ honeycomb core material. Transverse shear strengths at varying core thicknesses were compared to manufacturer specifications and used to determine normalised strength correction factors for thickness. These factors correlated well with trends shown in previous literature, where core shear strength decreases with increasing core thickness. The failure mode investigation showed a transition between modes as core thickness increased. The thinner cores experience shear fracturing of individual cell walls followed by local cell wall buckling, intermediate thickness cores initially failed by cell wall local buckling, then fractured and larger thickness cores appeared to fail by overall cell column buckling. [ABSTRACT FROM AUTHOR]

Purpose: The stress–strain behaviors of rockfill materials in dams are significantly affected by the anisotropy and grain crushing. However, these factors are rarely considered in numerical simulations of high rockfill dams. This study intends to develop a reasonable and practical constitutive model for rockfill materials to overcome the above problems. Design/methodology/approach: The effects of anisotropy and grain crushing are comprehensively considered by the spatial position of the reference state line. After the improved generalized plasticity model for rockfill materials (referred to as the PZR model) is developed and verified by laboratory tests, it is used with the finite element method to simulate the stress–strain behaviors of the Nuozhadu high core rockfill dam. Findings: The simulated results agree well with the laboratory tests data and the situ monitoring data, verifying the reliability and practicability of the developed PZR model. Originality/value: A new anisotropic state parameter is proposed to reflect the nonmonotonic variation in the strength as the major principal stress direction angle varies. This advantage is verified by the simulation of a set of conventional triaxial tests with different inclination angles of the compaction plane. 2) This is the first time that the elastoplastic model is verified by the situ monitoring data of high core rockfill dams. The numerical simulation results show that the PZR model can well reflect the stress–strain characteristics of rockfill materials in high core rockfill dams and is better than the traditional EB model. [ABSTRACT FROM AUTHOR]

In this research, the flexural behavior of lightweight biodegradable sandwich panel consisting of the outer green composite facesheets with polylactic acid (PLA) matrix and natural kenaf and cotton fibers, with five various stacking types of standard cardboard egg boxes cores under three‐point bending loads as an environmentally friendly alternative to conventional synthetic sandwich structures is investigated. The stiffness of this structure in bending is also studied using finite element simulations. The thickest specimen absorbed the most energy during flexural testing, however, the specimens containing two egg boxes inside each other were found to have a higher strength and stiffness. Using finite element method simulations to investigate the influence of composite facesheet thickness on flexural loads, it was found that the amount of the load carried by each sandwich specimen with doubled thickness was increased at least by about 50%. By changing the core's material from cardboard egg box to bamboo/PLA or kenaf‐cotton/PLA egg boxes, stiffness and strength and also the energy absorption were significantly increased. Therefore, it is possible to fabricate composite sandwich structures which are light and biodegradable for green environment and has the potential to replace many plastic products and structures that are used in food packaging and medium loads structures applications. [ABSTRACT FROM AUTHOR]

Implementation of natural fibers like kenaf in composite laminates has been the focus of many researchers. The considerable price of Low-Velocity Impact (LVI) testing, as well as the time constraints imposed by the short duration of this experiment, and prior reports of the obedience of Quasi-Static Indentation (QSI) test findings to LVI test results, have encouraged researchers to employ QSI instead of LVI. This work compares the mechanical characteristics of composite laminates consisting of chopped glass and kenaf fibers as a core and investigates the effect of hybridizing the mentioned chopped fibers as the core of a laminate. Three types of laminates with different core materials were fabricated to do this research. The results showed that among the laminates with the same weight, kenaf core laminate has the highest resistance against indentation and has the best performance in terms of absorbed energy, peak load, and damaged region. Using chopped kenaf fiber instead of chopped glass fiber can increase the absorbed energy and the peak load by 36% and 17%, respectively. Also, hybridizing the mentioned chopped fibers has not fully maximized the properties of the composite laminate during the QSI test. Finally, finite element modelling of the laminates was performed, and the numerical and experimental results were pretty aligned. [ABSTRACT FROM AUTHOR]

This paper presents the structural behavior of precast concrete sandwich panels (PCSPs) containing recycled tyre crumb rubber core under uni‐axial compression and compared with that containing commonly used expanded polystyrene (EPS) foam. A total of six panels were cast and tested. Two for each category of precast concrete panels that is, solid concrete panel, crumb rubber sandwich panel and foam sandwich panel. Results showed that the ultimate axial load of crumb rubber sandwich panel was found to be 91% of solid concrete panel and also exhibited higher structural response in comparison to foam sandwich panel. It was observed that all panels failed in a similar manner by crushing of concrete at ultimate load. Moreover, a finite element model was developed in ABAQUS using in‐built model of concrete plasticity damage to simulate the ultimate axial capacity of recycled tyre crumb rubber concrete sandwich panel and its failure in uniaxial compression. Analysis showed that the finite element modeling slightly overestimated the experimental results. Furthermore, the experimental test results showed that the recycled tyre crumb rubber can be utilized as an alternate core material in PCSPs without substantially compromising the ultimate strength or any change in structural response. [ABSTRACT FROM AUTHOR]

Purpose: The automotive industry extensively uses switched reluctance motors (SRM) because of their excellent performance. The main purpose of this article is to investigate the design of a particular type of SRM called doubly salient outer rotor switched reluctance motor (DSORSRM) for electric vehicle application in this paper. Design/methodology/approach: Different configurations of DSORSRM motor such as long flux path SRM, reduced flux path mutually coupled SRM and short flux path SRM (SF-SRM) are considered for investigation. The best configuration based on average torque is selected for further investigation by conducting an electromagnetic analysis. Also, in the proposed design, laminating material with low iron loss and superior performance characteristics is selected by doing electromagnetic analysis for SRM with M19, M660-50D, M-19 and M800-100A non-oriented laminating core material. Because vibrations are produced in DSORSRM devices as a result of changing induction, a mechanical analysis was performed to estimate the natural frequencies of vibration and the amplitudes that may lead to acoustic noises. Findings: SF-SRM configuration with three-phase, 12/10, 250 W, 48 V, 1,000 rpm is selected with the impact in the elimination of flux reversals and also has various salient features such as singly excited, no rotor windings, no permanent magnet, pure in construction and high starting torque. Still, this SRM suffers from vibration owing to changing induction. In lamination material selection, M19 is chosen as optimized material to obtain vibration reduction. Vibration analysis was performed for the optimized 12/10 SF-SRM with M19 lamination material, and the corresponding modes for the machine to operate with reduced vibration are analyzed. The current and speed characteristics of the prototype model for the DSORSRM motor are obtained and validated with finite element analysis (FEA) results. Originality/value: The performed FEA result shows that the proposed DSORSRM with short flux path configuration produces a high average torque of 1.915 N m. The M19 lamination material gives a minimum iron loss of 9.056 W. The modal frequencies are estimated and validated with numerical equations. [ABSTRACT FROM AUTHOR]

Prestressed fit is a new type of composite and metal connection. Compared with the traditional connection, it has the advantages of maintaining fiber continuity, high controllability, and high stability. According to the analytical model, the important parameters of the prestressed joint such as friction coefficient, lap length and winding tension are proposed. The influence of the parameters on the joint performance and stress distribution is studied by the finite element method. The abnormal end phenomenon, the stress relaxation phenomenon, and the stress mutation phenomenon caused by demolding during the joint forming process are explained, and the design of the layering method is optimized. The results show that the end effect makes the relationship between the lap length and the peak torque of the joint nonlinear, and increasing the lap length is beneficial to reduce this effect; before and after demolding, the end stress increases sharply; reducing the winding tension and selecting high modulus core mold materials are conducive to reducing stress relaxation; 90°inner ply angle and ± 45°outer ply angle are ideal layup methods for joint composite materials. [ABSTRACT FROM AUTHOR]

This paper presents a reluctance-based model considering the frequency-dependent loss nature of the windings for the analysis of three-phase five-leg transformers under grid voltages with direct current (DC) bias. This is very important especially for proper determination of their harmonic current distortion and maximum loading capability (MLC) under DC-biased grid voltage conditions. To figure out the developed model's validity under sinusoidal and DC-biased grid voltage cases, it is comparatively analyzed with the model based on 2D finite element method (FEM). Thus, for the considered transformer type operated under DC bias, the excitation current's harmonic pollution, losses, and reactive power demand parameters are analyzed by using the developed model. Additionally, by regarding these performance parameters, the DC susceptibilities of the considered-type transformer and the single-phase shell-type transformer are comparatively evaluated. Finally, for the studied grid voltage conditions, the effects of two important design considerations as (i) magnetic core material selection and (ii) legs' cross-sectional area sizing on the MLC are investigated. It is concluded from these investigations that under saturation conditions, the transformers, which have the core material with higher permeability or lower reluctance, draw higher excitation current, and have lower MLC ratio when compared to ones having the core material with lower permeability or higher reluctance. However, for unsaturated transformers, which work under DC bias, the case is the opposite to that in saturation conditions. On the other hand, under DC bias conditions, the effect of cross-sectional area sizing on the MLC ratio is much more for the transformer with high permeable magnetic core material with regards to ones with low permeable magnetic core material. [ABSTRACT FROM AUTHOR]

The size of magnetic components can be reduced with novel designs, but the intricate structures are difficult to make due to the limited sets of conventional magnetic core geometries and materials. Magnetic pastes have the flexibility of forming complicated structures with a pressure-less and low-temperature molding process, and are ideal for making the novel magnetic designs. The conventional approach of developing magnetic pastes involves time-consuming experimental iterations to determine the optimal composition parameters. Instead of relying on the trial-and-error efforts, we explored a computer-aided approach to guiding the magnetic paste development by creating material’s microstructure by discrete element method (DEM) and studying the property by finite element method (FEM). From a starting formula with two different-sized spherical powders, we improved the composition guided by DEM and FEM, and studied the magnetic permeability versus two variables: powder mixing ratio and magnetic volume fraction. The simulated permeability agreed well with the experimental data with an average error of only 10%. With the computer-aided formulation methodology demonstrated in this work, one can develop magnetic pastes with minimum experimental efforts and explore different compositions to meet various magnetic design needs. [ABSTRACT FROM AUTHOR]

The inversed Preisach hysteresis model is widely used to realize the rapid coupling of hysteresis characteristics of core materials in finite element analysis. However, the small major hysteresis loop is difficult to be accurately simulated. In this paper, an improved inversed Preisach model based on an improved parametric distribution function is proposed. By analyzing the magnetic remanence, the waveform factor is coupled with the parametric distribution function, and the identification of the small major hysteresis loop is strengthened. The distribution function parameters can be found from the limit hysteresis loop through the optimization algorithm. In the numerical calculation process of the model, the amplitude correction coefficient in the discrete formula is extracted by the basic magnetization curve. Compared with the previous method, this method simulates the limit hysteresis loop well and has higher simulation accuracy for the small major hysteresis loops. [ABSTRACT FROM AUTHOR]

This paper proposes an automatic design method of typical parameters such as number of phases, number of poles, stack thickness, stator outer diameter, rotor outer diameter, and number of turns of a switched reluctance motor from the requirement of the N‐T characteristic. In particular, a specific parameter related to the magnetic saturation is defined in order to arbitrarily determine how much to use the magnetic properties of the iron core material. In the proposed method, the typical motor parameters in order to realize a miniaturized volume which satisfies an input N‐T characteristic are obtained by setting the parameter related to magnetic saturation, maximum electrical frequency, maximum current density, maximum copper loss, conductor slot fill factor, magnetic properties of material, and input voltage. The designed motor is analyzed using the Finite Element Method (FEM) in order to validate the proposed method. [ABSTRACT FROM AUTHOR]

• Uncompensated gapped-core current transducer are sensitive to nearby currents. • We analyze this crosstalk by 3-D FEM and compare it to the measurements. • Ferrite core with two 2 mm airgaps has and error up to 18 % • By improving the design, the error can be reduced to 0.15 % • However, this type of sensor is very sensitive to the position of the Hall sensor. A detailed analysis of the crosstalk in an uncompensated gapped-core current transducer is presented in this paper. A cut-core current transducer with a magnetic field sensor in the airgap is widely used to measure current in industry and in laboratories. Crosstalk is the effect of a nearby current-carrying conductor on the reading of this type of sensor. We present a study of the dependence of the crosstalk on the position of the external conductor, the core material, and the core geometry, including the number of airgaps. A 3D Finite Element Method (FEM) based model is used to analyze the crosstalk, and the results are compared with measurements. Using a low-permeability ferrite core with two 2 mm airgaps and a single Hall sensor results in a maximum crosstalk error of 18 %. This error can be reduced to 1 % either by using a differential Hall sensor pair, or surprisingly by using a single 4 mm airgap. This error can be further reduced to 0.15 % by using an FeSi core with larger permeability. However, this type of sensor is very sensitive to the position of the Hall sensor in the center of the airgap. Displacement or an angular mismatch can increase the error to 1.5 %, as demonstrated on a commercial sensor. [ABSTRACT FROM AUTHOR]

Accurate modeling of losses in ferrite cores is of high interest for power electronics design. Left aside the problem of modeling the constitutive law, accurate computation of losses require to model the 3d geometry, for instance by Finite Element (FE) analysis, which is computationally expensive. This hinders the practical usage of such models in circuit simulators which require "light" models. In this work we devise a new approximate method to take into account the microscopic structure of toroidal ferrite cores, which boils up into simple analytical formulas. The proposed method is compared to experimental measurements on a T38 ferrite core, and a FE model. • A simplified, analytically model of losses in ferrite cores is presented. • Comparison between simplified model, Finite Element model and measurement is taken on. • The parameters of the model are not fitted, but derived from the knowledge of the structure of the core and of the material used. [ABSTRACT FROM AUTHOR]

In order to improve the mechanical performance of the core energy-dissipating material of the viscoelastic damper, a novel Nanometakaolin-reinforced Fluororubber Sector Damper (NFSD) is proposed for providing a strong guarantee for the seismic safety of the structure joints subjected to seismic earthquake. Firstly, in order to systematically study the shock absorption performance of NFSD, the core energy dissipation material(nano metakaolin reinforced fluororubber composite) of NFSD is prepared by melt blending method, and the vulcanization performance and microscopic mechanism of the nano composite are analyzed by vulcanization test and X-ray diffraction test. Secondly, the nanocomposite material is used as the core energy dissipation material, and NFSD based on nano reinforced fluororubber is proposed. Finally, the dynamic characteristics of NFSD and the structural seismic performance of NFSD controlled reinforced concrete (RC) frames are studied using refined finite element simulation methods. The research results indicate that 20 phr NMK increase the maximum torque M H of FKM by 20 %, while also shortening the scorching time t 10 by 0.28 min. It means greatly improving the vulcanization performance of FKM. Compared to uncontrolled structures, NFSD reduces the peak displacement, interstory displacement angle, and maximum vertex acceleration of the 4-story RC structure by 16.2 %−67.4 %, 12.4 %−64.6 %, and 16.8 %−43 %, respectively. NFSD possesses excellent seismic absorption performance. • The nano metakaolin reinforced fluororubber compositeswas prepared by melt blending method. • The vulcanization performance and microscopic mechanism of the nanocomposites were analyzed by vulcanization test and X-ray diffraction test. • The dynamic characteristics of the NFSD were investigated. • The structural seismic performance of NFSD controlled reinforced concrete (RC) frames were achieved by using refined finite element simulation methods. [ABSTRACT FROM AUTHOR]

• Perforation tests of integrally-3D printed trabecular core sandwiches. • The skin material was found to be rate-independent. • The rate-dependent behaviour was attributed to the core material's rate dependency. • Finite element models should be enhanced to predict the fracture behaviour. Sandwich panels are heavily used in industrial sectors where specific mechanical properties are of utmost importance due to their high weight-stiffness ratio and energy absorption capacity. Lightweight sandwich cores with bio-inspired topologies have been used as an advanced alternative to conventional bulk cores to improve performance. Nowadays, sandwich structures comprised of core and skins are typically manufactured with two different processes and are afterwards adhesively joined together. Here, with a less time-consuming and more efficient assembly procedure in mind, an integrally 3D-printing strategy is proposed. This investigation analyses the low-velocity impact and quasi-static perforation performance of sandwich core designs inspired by the beetle's forewing trabecular structure. It was found that the core material was responsible of the rate dependence observed in the force–displacement curves. More complex finite element models than those employed here are necessary to capture all the fracture modes observed experimentally. [ABSTRACT FROM AUTHOR]

• S-core sandwich panel composites design and manufacturing were done. • Finite element modeling and mechanical tests were performed in three-point bending. • Bending behaviors were compared. Sandwich panel composites have numerous applications in material technology. The sandwich panel composite structure's mechanical behavior and performance are determined by the material properties and geometry of the relevant components. The top and bottom sheets of the designed sandwich panel composite material are made of stainless steel-316, the core material is aluminum 1050A-0, and the binding element is DP-8405 acrylic adhesive. Three-point bending tests and finite element models were utilized to investigate the bending behavior of S-core composite sandwich panels. Finite element models have been developed to characterize the effect of composite element bending behavior on variations. The specific flexural modulus and strength of composite S-core sandwich structures can be compared to core structures in the literature in general. As a consequence, the minimum weight design was used as a guideline to produce weight and density-efficient hybrid composite sandwich panels. The load-carrying capacity of the composite panel increased as the wall thickness of the S-shaped core increased when the damage loads were examined in the variations. It has been ascertained that as the core height increases, the load-carrying capacity of the composite panel decreases. [ABSTRACT FROM AUTHOR]

The magnetically coupled three‐phase dual‐active‐bridge (DAB3) DC‐DC converter is highly suitable for high‐power applications. Although the converter has many advantages, the structure, working mode and electromagnetic effect of its key magnetic component—high‐power medium‐frequency three‐phase transformer (MFT3) is more complex, and the capacity, frequency, loss, temperature rise and leakage inductance restrict each other, forming a complex and systematic design problem. This paper focuses on the overall design method and performance of high‐power MFT3. Based on the analysis of steady‐state voltage and current waveforms of DAB3 converter, the expression of harmonic current is derived by using fundamental wave analysis, and the analytical calculation method of copper loss is proposed. According to the piecewise linear flux density waveform excited by six‐step voltage wave, the modified IGSE method is proposed to calculate the core loss. For MFT3 with three‐phase five column core topology, a lumped parameter thermal network model with 14 temperature nodes is established to obtain the temperature rise. The influence of winding arrangement on leakage inductance is analyzed, and the analytical expression of leakage inductance is presented. On this basis, the design method of high‐power MFT3 is proposed based on the free parameter scanning method. A 5 kHz, 15 kW MFT3 model with the nanocrystalline core material is made, and the leakage inductance, core loss, copper loss and temperature rise are extracted by finite element method (FEM) and experiment. The effectiveness of the proposed method is verified by comparing the design results with the FEM simulation and experimental results. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A low confinement loss of hollow-core photonic crystal Fiber (HC-PCF) for liquid-/gas-sensing applications has been proposed. Various HC-PCF backgrounds such as silica, BK7 and Teflon glass with different core materials such as glycerol, benzene and toluene have been studied using a finite element method with perfectly matched layer-based COMSOL software. The performance of the proposed PCF is analyzed using different metrics such as confinement loss, effective area, numerical aperture, relative sensitivity and effective refractive index for different combinations to compare the effects of different backgrounds in HC-PCF. The proposed HC-PCF structure offers relative sensitivity of 91.96% and 1.74 × 10−14 dB/m of confinement loss using Teflon glass as the substrate for benzene. The proposed PCF can be used for liquid- and gas-sensing applications with its low confinement loss and high sensitivity. The proposed simple cladding structure is easy to fabricate and offers 26% improved relative sensitivity compared to existing PCFs in the literature. [ABSTRACT FROM AUTHOR]

Hybrid scaffolds consisting of a three-dimensional network of hollow struts of β-tricalcium phosphate (β-TCP) with cores filled with polycaprolactone (PCL) were fabricated. For the development of the ceramic structures the additive manufacturing technique known as Digital Light Processing (DLP) was employed. After sintering, cores were infiltrated with molten PCL by suction. The enhancement of the scaffolds' compressive strength and toughness upon infiltration was evaluated through uniaxial compression tests. The effect of the core diameter on the mechanical performance was also analyzed. Moreover, a comprehensive finite element analysis was carried out to broaden the study on the effect of core/shell respective diameters and to analyze the role of the modulus of the core material on the strength of the hybrid structure. [ABSTRACT FROM AUTHOR]

This paper presents a novel point of view for the performance investigation and optimization of energy absorber devices, which is numerically introduced using the finite element method employing corrugated tubes. The numerical results show that structural or material softening leads to an optimal configuration at which the corrugated or circular tube achieves its peak performance. The performance and optimization parameters used in this study are absorbed crash energy and specific energy absorption. The force-displacement (f-d) diagram of the energy absorbers is divided into three parts for numerical investigation. The optimum point of each corrugated tube is observed when the values of energy absorption (EA) at different stages of the stroke (i.e., in the first, middle, and last portions of deformation) are almost equal or close to one another. Furthermore, the effect of material softening is discussed. The effects of cladding a ductile layer on f-d diagram, EA and deformation of thin-walled circular tubes are numerically investigated. Adding soft material layers oriented at 30° to 70° to the model can increase the performance of energy absorbers by approximately 10 % compared with the model that uses only the core material. [ABSTRACT FROM AUTHOR]

This article presents the rotor optimization in an interior permanent magnet synchronous machine (IPMSM) with high-strength non-grain-oriented (NGO) silicon steel material. Different from simple replacement with high-strength NGO, this article presents a customized design to make the best use of rotor iron core material. Specific optimization of the rotor topology is presented, followed with simulation verification by finite element method (FEM). Based on the simulation results, the benefits and limitations of the optimization design with the replacement of high-strength NGO are listed. In order to further overcome the limitations of the presented optimization design, magnetic characteristics of the high-strength NGO laminations subjected to various tensile stresses are measured in the experiment. Finally, experimental results are analyzed, and the conclusions to employ high-strength NGO for IPMSM are summarized. [ABSTRACT FROM AUTHOR]

The residual flux measurement is one of the difficulties in the transformer research field. This article presents a residual flux density (${B} _{\mathrm {r}}$) measurement method considering the relative differential permeability ($\mu _{\mathrm {rd}}$) of the core material. First, the basic relationship between $\mu _{\mathrm {rd}}$ and ${B} _{\mathrm {r}}$ is analyzed on the basis of the magnetic domain theory. Then, combining the experimentally measured relationship between ${B} _{\mathrm {r}}$ and $\mu _{\mathrm {rd}}$ , using $\mu _{\mathrm {rd}}$ as an intermediate variable, the relationship between ${B} _{\mathrm {r}}$ and time constant is derived. Furthermore, a square iron core model is established by the finite-element method, and the empirical formula for calculating ${B} _{\mathrm {r}}$ is was fit. Finally, the feasibility of this method and the accuracy of the proposed empirical formula are verified through experiments. [ABSTRACT FROM AUTHOR]

This study presents a new higher-order refined analysis model for static and free vibration analysis of a sandwich plate with soft functionally graded material core. The governing equations are derived from equilibrium differential equations of motions. The accuracy and convergence of the present model and numerical solution are validated versus available results. Variable length width ratios, thickness ratios between skins and core and span-to-thickness of sandwich plates have been studied. Obtained results show that suggested model can achieve greater accuracy for sandwich plates with soft functionally graded material core, as compared to existing functionally graded sandwich plate analysis models and models based on finite element method. Finally, parametric study has been carried out to investigate influence of volume fraction distribution, thickness to side ratio and material properties on the plate bending and free vibration. [ABSTRACT FROM AUTHOR]

In the present study, the free and forced vibration responses of the composite sandwich plate with carbon nanotube reinforced honeycomb as the core material and laminated composite plates as the top and bottom face sheets are investigated. The governing equations of motion of hybrid composite honeycomb sandwich plates are derived using higher order shear deformation theory and solved numerically using a four-noded rectangular finite element with nine degrees of freedom at each node. Further, various elastic properties of honeycomb core materials with and without reinforcement of carbon nanotube and face materials are evaluated experimentally using the alternative dynamic approach. The effectiveness of the finite element formulation is demonstrated by performing the results evaluated experimentally on a prototype composite sandwich plate with and without carbon nanotube reinforcement in core material. Various parametric studies are performed numerically to study the effects of carbon nanotube wt% in core material, core thickness, ply orientations, and various boundary conditions on the dynamic properties of composite honeycomb sandwich plate. Further, the transverse vibration responses of hybrid composite sandwich plates under harmonic force excitation are analyzed at various wt% of carbon nanotubes and the results are compared with those obtained without addition of carbon nanotubes to demonstrate the effectiveness of carbon nanotube reinforcement in enhancing the stiffness and damping characteristics of the structures. The study provides the guidelines for the designer on enhancing both the stiffness and damping properties of sandwich structures through carbon nanotube reinforcement in core materials. [ABSTRACT FROM AUTHOR]

Auxeticity of materials improves several of their mechanical properties, especially shear, impact, and bending resistance. It also improves ability of materials to absorb impact energy as well as the overall stiffness of structures. In this research, authors examine synclastic panels made from novel wood‐based composites. The aim is to determine the force–displacement characteristics during uniaxial compression and obtain the stiffness of the panels. These data allow one to predict the behavior of a panel during two‐axial bending with different support scenarios. Finite element method (FEM) analysis is performed, with the use of model material, to determine the impact of varied facings thickness as well as different types of materials and core structures, on the stiffness of synclastic panels. It is demonstrated that proposed multilayer composites allow forming (technologically difficult) spherical shapes, without additional heat and pressure treatment. The type of an outer layer material strictly determines the usability and ease of two‐axial bending process. Presented composites are interesting materials, that can be adopted into the wood industry as a replacement for traditional materials, e.g., bent plywood. [ABSTRACT FROM AUTHOR]

This article presents a finite element method (FEM) integrated with the nonlocal theory for analysis of the static bending and free vibration of the sandwich functionally graded (FG) nanoplates resting on the elastic foundation (EF). Material properties of nanoplates are assumed to vary through thickness following two types (Type A with homogeneous core and FG material for upper and lower layers and Type B with FG material core and homogeneous materials for upper and lower layers). In this study, the formulation of the four-node quadrilateral element based on the mixed interpolation of tensorial components (MITC4) is used to avoid "the shear-locking" problem. On the basis of Hamilton's principle and the nonlocal theory, the governing equations for the sandwich FG nanoplates are derived. The results of the proposed model are compared with published works to verify the accuracy and reliability. Furthermore, the effects of geometric parameters and material properties on the static and free vibration behaviors of nanoplates are investigated in detail. [ABSTRACT FROM AUTHOR]

Fringing losses play a detrimental role in high-frequency transformers. The tendency toward higher power density and miniaturization of power converters leads to higher switching frequency and enforces the use of low-profile components such as gapped planar transformers. Due to the air gap, lower magnetizing inductance and better regulation of LLC (Lm, L2, Cs) can be achieved, but fringing fluxes can also be induced, resulting in extra magnetic losses and more hotspots. These losses are highly dependent on the frequency and the core material, so it is critical to model them for gapped planar transformers in LLC resonant converters, which operate at high frequencies and use ferrite material. In this article, fringing losses for gapped ferrite transformers in LLC converters are thoroughly modeled in order to provide a precise prediction regardless of the materials and core geometries. The proposed method provides an accurate and compact formula for predicting the fringing losses of planar transformers. This formula is obtained based on the finite-element method so as to consider and evaluate different design parameters. An LLC resonant converter with different planar transformers is implemented to show the compatibility of the proposed model. Experimental results show the higher accuracy of the proposed model compared to traditional ones and confirm that the proposed loss model can be applied to diverse core shapes. In addition, the gradient descent method is used to calibrate the theoretical and experimental results. Moreover, temperature deviations of the transformer due to the fringing losses are measured and evaluated both experimentally and theoretically to show the accuracy of the proposed loss formula. Due to the proposed model's higher accuracy, an improved design procedure for planar transformers is obtained, adding substantial value for design engineers. [ABSTRACT FROM AUTHOR]

A sandwich structure consists of a two thin and strong facesheets, bonded to a thick lightweight core material. The mechanical response of a sandwich structure depends on the properties of its constituents. A numerical model and experimental validation of the three-point bending test of sandwich composites are presented in this study. The core material is aluminum honeycomb. The facesheets are made of IM7/Cycom5320-1, which is a carbon fiber/epoxy prepreg system. A comprehensive model of the failure under flexural loading was developed. Facesheet failure was modeled using Hashin's failure criteria. A detailed meso-scale model of the honeycomb core was included in the model. The experiments indicated that failure initiation was due to local buckling in the honeycomb core. Failure propagation was in the form of core failure, facesheet compressive failure, and interlaminar failure. The developed meso-scale model was able to accurately simulate failure initiation and propagation in the composite sandwich structure. The effect of elevated temperature on the three-point bending behavior was studied numerically as well as experimentally. An increase in test temperature to 100°C resulted in a drop of 9.2% in flexural strength, which was also predicted by the numerical model. [ABSTRACT FROM AUTHOR]

We propose two mid-infrared photonic crystal fibers with an elliptical As2S3 core and a dual-cladding structure with high birefringence and high nonlinearity. The cladding filling material is silica and the core material is As2S3. The full vector finite-element method is used to study the birefringence, and nonlinear coefficient of the structure in the 3–5 μm band. The Simulation results show that the birefringence of the two structures can reach a maximum of 0.2169, and the nonlinear coefficient can reach a maximum of 3763.42 W−1/km. From these characteristics, it is concluded that the proposed structure will be ideal for mid-infrared fiber sensing, precision optics and nonlinear optics. [ABSTRACT FROM AUTHOR]

This article describes a method to calculate iron loss of permanent-magnet machines by considering the hysteresis loops affected by multi-axial stress. A simple hysteresis model is introduced and modified by reluctivity and hysteresis loss increase ratios, which can be determined by core material experiments under uniaxial stress. This model is coupled with time-stepping finite-element analysis. The validity of the proposed method is confirmed by the core material experiments under multi-axial stress and measured characteristics of permanent-magnet machines. It is clarified that the accuracy of the proposed method is acceptable. [ABSTRACT FROM AUTHOR]

A solid core photonic crystal fiber (PCF) is preferred to signify the work of circular-pattern PCF for chemical identifying motive. Finite element method is used to obtain several properties of PCF. Various computations are applied to numerically explore the use of PCF for sensing justifications at different wavelengths ranging between 1.4 and 1.65 μm. The solid core is filled with liquid glycerol (n = 1.4722), ethanol (n = 1.354), and toluene (n = 1.4968), and on applying various geometric parameters of the fiber, 65.16%, 61.65%, and 64.05% of sensitivity are observed respectively. Transmission of heavy data with high speed depends on effective mode area. For glycerol and toluene, the effective area is observed as 2.81 μm2 and 3.07 μm2 respectively. Perfectly matched layer is applied in outer most cladding to overcome reflection. Higher sensitivity is observed by this design operating at different wavelengths. Similarly, properties like confinement loss and effective area are also computed. Design containing core material such as glycerol, ethanol, and toluene has been compared by different properties. The core materials employed in this paper are used to analyze the potential of sensors. This PCF can be used in diverse application of bio sensing or sensing related areas. [ABSTRACT FROM AUTHOR]

The article presents the results of experimental and finite element analyses of the flexural vibration behavior sandwich composite with different debonding ratios. Sandwich composite consists of two thin skins composed of E-glass fiber and epoxy resin bonded to lightweight and weaker core material of PVC foams. Experimental tests using the impulse technique were performed on the sandwich constituents and sandwich composites with different debonding lengths. The modal dynamic characteristics of sandwich composite were measured and discussed for each debonding ratio. A finite element modeling was used to determine the natural frequencies, modal shapes, and stress and strain fields for each element of sandwich composites for each debonding ratio. The modal strain energy approach was used to determine the contribution of energies dissipated of the core and the skins in the total dissipated energy and the global damping of the different sandwich composites. The results obtained by this approach are compared with those obtained experimentally. [ABSTRACT FROM AUTHOR]