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Towards a sustainable future in construction, worldwide efforts aim to reduce cement use as a binder core material in concrete, addressing production costs, environmental concerns, and circular economy criteria. In the last decade, numerous studies have explored cement substitutes (e.g., fly ash, silica fume, clay-based materials, etc.) and methods to mimic the mechanical performance of cement by integrating polymeric meshes into their matrix. In this study, a systemic approach incorporating computer aid and biomimetics is utilized for the development of 3D-printed clay-based composite mortar reinforced with advanced polymeric bioinspired lattice structures, such as honeycombs and Voronoi patterns. These natural lattices were designed and integrated into the 3D-printed clay-based prisms. Then, these configurations were numerically examined as bioinspired lattice applications under three-point bending and realistic loading conditions, and proper Finite Element Models (FEMs) were developed. The extracted mechanical responses were observed, and a conceptual redesign of the bioinspired lattice structures was conducted to mitigate high-stress concentration regions and optimize the structures' overall mechanical performance. The optimized bioinspired lattice structures were also examined under the same conditions to verify their mechanical superiority. The results showed that the clay-based prism with honeycomb reinforcement revealed superior mechanical performance compared to the other and is a suitable candidate for further research. The outcomes of this study intend to further research into non-cementitious materials suitable for industrial and civil applications. [ABSTRACT FROM AUTHOR]

Raised access floors are nowadays widely used in buildings. A novel raised access flooring product is developed by this research, with a set of sustainable features, including less environmental impact and high strength. Its floor panels are made of polyurethane (PU) reinforced with glass fibre, which is light-weight and fire-resistant, replacing the traditional floor panel materials, and the panels are supported by simplified steel stringers to reinforce the strength of the flooring product. Instead of the conventional sandwich design consisting of a core material encapsulated by outer layers, the new floor panel design adopts the reinforced PU as its sole material, which not only simplifies the structure but also reduces floor weight and costs. The sustainable advantage is further approved by the environmental life cycle assessments of the new raised flooring product in comparison to traditional ones made of cement and woodchips, with results showing that the new floor product's total environmental impact is 52% less than cement floor and 47% less than woodchip board floor. Further, the finite element analysis (FEA) was carried out, and the experimental test was conducted to verify the FEA results, indicating that the new product's strength is higher than the requirements of the raised access flooring product standards. There is no raised access flooring product made of PU reinforced with glass fibre available in the market, and, hence, the new product developed by this research is a novel contribution. [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]

This study analyzes the blast resistance in triple-period minimal surface (TPMS) sandwich panel structures with a cellular structure. The explosion test of the TPMS sandwich panel was carried out, and experimental data verified the effectiveness of the finite element model. Four TPMS configurations, Diamond, Gyroid, IWP, and Primitive, were selected as the core of the sandwich panel to determine the dynamic response process of the TPMS sandwich panel under the action of a blast load. The effects of the thickness of the core material and the explosive charge on the blast resistance in the TPMS sandwich panel were investigated. The results show that the increase in core thickness reduces the blast energy absorption efficiency of the sandwich panel, and the energy resistance in the Diamond configuration sandwich panel is stronger than the other three configurations under the same blast load; the increase in explosive charge significantly increases the displacement of the sandwich panel, and the Gyroid configuration shows better energy absorption effect; different TPMS configurations and panel thickness have a significant effect on the deformation and energy absorption of the sandwich panel under the blast load. The results of this study can promote the application of TPMS sandwich structures in blast-resistant structures. [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]

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]

A single-polarization solid-core anti-resonant fiber is proposed, and the influence of the fiber core material anisotropy of the solid-core anti-resonant fiber on polarization characteristics is investigated using the finite element method. Single-polarization guidance is achieved by using the anisotropy of optical fiber materials, which also ensures high birefringence. The numerical simulation results indicate that there are two single-polarization intervals (1210–1440 nm and 1490–1560 nm), with a maximum bandwidth of up to 230 nm, when the confinement loss difference between the two orthogonal polarizations exceeds two orders of magnitude. Specifically, when the work wavelength is 1550 nm, a polarization extinction ratio (PER) of 108 is obtained by optimizing the structure parameters. Additionally, the y-polarization fundamental mode (YPFM) can be well confined in the fiber center with a low confinement loss of 0.04 dB/m, while the x-polarization fundamental mode (XPFM) has a huge confinement loss larger than 4.65 dB/m due to the coupling with the tube mode. The proposed single-polarization solid-core anti-resonant fiber has a huge potential in applications such as laser systems, fiber-optic gyroscopes, and optical fiber communications. [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]

This paper proposes a portable 11 kW off-board charger for electric vehicles. In the ac/dc stage, a three-phase power factor correction (PFC) in Vienna topology is chosen. The loss and volume of the PFC inductance are calculated over a wide range of parameters and optimized with regard to design, winding, and core material. A three-phase LLC resonant converter operating at 1 MHz is chosen for the galvanically isolated dc/dc stage. A parametrizable loss model of the high-frequency transformer and the resonance inductor is developed to minimize volume, weight, and losses. With the help of an automated algorithm using these loss models, the inductive components are optimized in terms of winding specification, magnetic material, and core geometry, verified by finite element analysis and measurements. For the ac/dc stage, 900 V SiC devices are adopted, and 1200 V SiC devices are used in the primary and secondary sides of the dc/dc stage. A variable dc-link voltage is utilized to adjust the charging profile and to operate the LLC resonant converter at the most efficient point near the series resonance frequency. A mechatronically integrated portable air-cooled off-board charger prototype with 11 kW, three-phase 400 VAC input, and 620–850 VDC output is realized and tested. The prototype demonstrates a power density of 2.3 kW/liter (37.7 W/in³), a peak efficiency of 96%, and 95.8% efficiency over the defined battery voltage range. [ABSTRACT FROM AUTHOR]

The objective of this research is the fabrication of biodegradable starch-based sandwich materials. The investigated sandwich structures consist of maize starch-based films as skins and biodegradable 3D-printed polylactic filaments (PLA) as the core. To investigate the tensile properties of the skins, conventional and nanocomposite films were prepared by a solution mixing procedure with maize starch and glycerol as the plasticizer, and they were reinforced with sodium montmorillonite clay, cellulose fibers and fiberglass fabric, with different combinations. Test results indicated a significant improvement in the mechanical and morphological properties of composite films prepared with sodium montmorillonite clay in addition with cellulose fibers and fiberglass fabric, with 20 wt% of glycerol. The morphology of the skins was also examined by scanning electron microscopy (SEM). Three orders of hierarchical honeycombs were designed for the 3D-printed core. To investigate how the skin material and the design of the core affect the mechanical properties of the starch-based sandwich, specimens were tested under a three-point bending regime. The test results have shown that the flexural strength of the biodegradable sandwich structure increased with the use of a second order hierarchy core and starch-based skins improved the strength and stiffness of the neat PLA-based honeycomb core. The bending behavior of the hierarchical honeycombs was also assessed with finite element analysis (FEA) in combination with experimental findings. Flexural properties demonstrated that the use of starch-based films and a PLA honeycomb core is a suitable solution for biodegradable sandwich structures. [ABSTRACT FROM AUTHOR]

Inorganically-bound core materials are used in foundries in high quantities. However, there is no validated mechanical failure criterion, which allows performing finite-element calculations on the core geometries, yet. With finite-element simulations, the cores could be optimised for various production processes from robotic core handling to the decoring process after the casting. To identify a failure criterion, we propose testing methods, that enable us to investigate the fracture behaviour of inorganically-bound core materials. These novel testing methods induce multiple bi-axial stress states into the specimens and are developed for cohesive frictional materials in general and for sand cores in particular. This allows validating failure criteria in principal stress space. We found that a Mohr-Coulomb model describes the fracture of inorganic core materials in a plane stress state quite accurately and adapted it to a failure criterion, which combines the Mohr-Coulomb model with the Weakest-Link theory in one consistent mechanical material model. This novel material model has been successfully utilised to predict the fracture force of a Brazilian test. This prediction is based on the stress fields of a finite element method (FEM) calculation. [ABSTRACT FROM AUTHOR]

Athree-layer composite plate element is developed for finite element modeling and vibration analysis of sandwich plate with frequency-dependent viscoelastic material core. The plate element is quadrilateral element bounded by four-node with 7-degree-of-freedom per node. The frequency-dependent characteristics of viscoelastic material parameters are described using the Biot model. The method of identifying the parameters of the Biot model is given. By introducing auxiliary coordinates, the Biot model is combined with the finite element equation of the viscoelastic sandwich plate. Through a series of mathematical transformations, the equation is transformed into a standard second-order steady linear system equation form to simplify the solution process. Finally, the vibration characteristics of the viscoelastic sandwich plate are analyzed and experimentally studied. The results show that the method in this paper is correct and reliable, and it has certain reference and application value for solving similar engineering vibration problems. [ABSTRACT FROM AUTHOR]

In this work, a finite element model was developed for vibration analysis of sandwich beam with a viscoelastic material core sandwiched between two elastic layers. The frequency-dependent viscoelastic dynamics of the sandwich beam were investigated by using finite element analysis and experimental validation. The stiffness and damping of the viscoelastic material core is frequency-dependent, which results in complex vibration modes of the sandwich beam system. A third order seven parameter Biot model was used to describe the frequency-dependent viscoelastic behavior, which was then incorporated with the finite elements of the sandwich beam. Considering the parameters identification, a strategy to determine the parameters of the Biot model has been outlined, and the curve fitting results closely follow the experiment. With identified model parameters, numerical simulations were carried out to predict the vibration and damping behavior in the first three vibration modes, and the results showed that the finite model presented here had good accuracy and efficiency in the specific frequency range of interest. The experimental testing on the viscoelastic sandwich beam validated the numerical predication. The experimental results also showed that the finite element modeling method of sandwich beams that was proposed was correct, simple and effective. [ABSTRACT FROM AUTHOR]