Core Configuration Research Articles

Out-of-plane engineering constants of beetle elytra inspired sandwich cores

The Beetle Elytron Plate (BEP) is a new type of biomimetic sandwich core developed as a potential replacement of classical honeycomb cores in sandwich panels. This work investigates the out-of-plane engineering elastic constants, including Young's and pure shear moduli of parametric BEP cellular topologies. The BEP core configurations are simulated using Finite Element models, with both full-scale and representative unit cells for asymptotic homogenization. The numerical models are also validated by flatwise compression and out-of-plane pure shear loading experiments performed according to ASTM standards. The benchmarked models are then used to perform a parametric analysis of the beetle elytra cellular cores against their geometry characteristics. Results show that the out-of-plane Young's modulus E3/Esand the transverse pure shear modulus G31/Es of both BEP configurations are larger than those of the classic hexagonal honeycombs and increase when the size of the unit cell cylinders, or rib thickness become large. The specific shear moduli of the beetle-elytra inspired honeycombs are however lower than those of classical pure hexagonal honeycomb configurations, although the added presence of cylinders within the cell configuration offers opportunities for tailoring the design of multifunctional cores.

Evaluation of corrugated core configuration effects on low-velocity impact response in metallic sandwich panels

Abstract Sandwich panels are used as body components of vehicles in many sectors, such as defense, aircraft, and aviation, due to their advanced mechanical properties and lightness. This study aims to investigate the effect of core configurations on mechanical performance and deformation behavior of metallic sandwich panels under low-velocity impact loading. For this purpose, metallic sandwich panels having monolithic and sliced core configurations were first produced. Low-velocity impact tests were carried out using varying energy levels (20, 40, 60 J) to examine how the intensity of influence affects the deformation of the sandwich panel. The perforation and deformation behavior on the upper surface plates of sandwich panels were evaluated. Experimental results showed that the core design significantly affects the impact behavior of sandwich panel samples. The sliced core configuration produced approximately 10 % more maximum contact force and absorbed 14 % more impact energy at high-impact energy levels. Additionally, the sliced core configuration delayed core collapse of the core in deformation situations where complete perforation does not occur.

An all-composite sandwich structure with PMI foam-filled for adjustable vibration suppression and improved mechanical properties

A novel all-composite double-layer sandwich structure with tubular cores (DSST) is designed and fabricated to achieve the both of vibration suppression and enhancement of mechanical properties. The suppression effect of the proposed sandwich structure on the structural vibration is verified numerically and experimentally, and the mechanism of bandgap generation as well the structural wave propagation modes are revealed and analyzed. The anisotropy of the carbon fiber reinforced polymer (CFRP) is utilized to enables the intermediate resonant layer to exist a wide frequency adjustment range of vibration suppression without altering its geometrical parameters. Then, the improvement of structural vibration characteristics (i.e., natural frequencies and mode shapes) by filling the polymethacrylimide (PMI) foam in the DSST is discussed. And PMI foam-filling also leads to improved mechanical properties, out-of-plane compression tests are conducted to reveal the mechanism of mechanical enhancement, and it is found that the interaction effect of the foam filled in DSST in the axial direction enhances the compressive strength and the specific energy absorption (SEA) compared to the one without foam by 35.7 % and 26.2 %, respectively. In addition, the core configuration and the composite material preparation enable the proposed structure to outperform competing ones in terms of load-bearing capacity and bandgap characteristics.

Influence of mixed core in the radionuclides releases and hydrogen production for VVER-1000

This paper aims to compare the behaviour of VVER-1000 Nuclear Power Plants (NPPs) under DEC-A/B conditions, contemplating different fuel assemblies considered in mixed cores. The main characteristics of both fuel assemblies are described in this paper, with a focus on highlighting the key differences in mass composition.There are three models under consideration: Model A, Model B and Model C. Model A consists of a core entirely filled with fuel assemblies equipped with grids made of Zr-1 %Nb, referred to as “Type A” through the paper. Model B comprises a core filled with fuel assemblies that have grids made of Alloy 718 (aka Inconel), referred to “Type B”. Lastly, Model C features a mixed core of 151 fuel assemblies with Zr-1 %Nb grids and 12 fuel assemblies with Inconel grids.Initially, the primary distinctions between these fuel assemblies types are the number and composition of their spacer grids. Type A fuel assemblies have 13 grids made of Zirconium, while Type B fuel assemblies have 16 grids made of Inconel. It was initially anticipated that the reduction in the mass of zirconium available for oxidation would lead to lower hydrogen production in Model B compared to Model A. However, it was observed that the Inconel grids in Type B fuel assemblies provide enhanced structural support, prolonging the oxidation reaction and yielding more hydrogen during the initial oxidation phase compared to Type A fuel assemblies.Moving on to the mixed core configuration (Model C), the Inconel grids in Type B fuel assembly also offer superior structural support. This results in an extended oxidation process. The Type A fuel assemblies having a significant zirconium mass, oxidation in intensified, causing a rise in temperature due the exothermic reaction and leading to the producing of a greater amount of hydrogen compared to the other two models. This pattern is also observed in radionuclide releases.In conclusion, this study sheds light on the behaviour of VVER-1000 NPPs under DEC-A/B conditions, considering different fuel assembly types and mixed core configurations. The results indicate that the choice of grid materials significantly influences the oxidation process and hydrogen production, with Inconel grids exhibiting extended oxidation and hydrogen generation behaviour in both pure and mixed core setups.

Analysis of the Main Architectural and Structural Design Considerations in Tall Timber Buildings

Tall timber buildings represent an emerging and highly promising sector due to their potential to yield significant environmental and economic advantages throughout their entire life cycles. Nonetheless, the existing body of literature lacks a comprehensive exploration of the primary architectural and structural design considerations for such sustainable towers. To address this gap and to enhance our understanding of emerging global trends, this study scrutinized data from 49 tall timber building case studies from around the world. The key findings revealed the following: (1) Europe stood out as the region boasting the highest number of tall timber buildings, with North America and Australia following behind; (2) residential applications were the most preferred function for tall timber buildings; (3) central cores were the predominant choice for core configuration; (4) prismatic forms were the most prevalent design preferences; (5) composite materials were notably widespread, with timber and concrete combinations being the most prominent; (6) structural systems primarily featured shear–frame systems, especially shear-walled frames. By unveiling these contemporary characteristics of tall timber buildings, this research is expected to provide valuable insights to architects, aiding and guiding them in the design and execution of future sustainable projects in this field.

The Spatial Configuration of Traditional Urban Core of Zakho City

The Spatial Configuration of Traditional Urban Core of Zakho City

High-Rise Residential Timber Buildings: Emerging Architectural and Structural Design Trends

High-rise residential timber buildings (≥8 stories) are an emerging and promising domain, primarily owing to their capacity to deliver notable environmental and economic benefits over the entire span of their existence. However, it is worth noting that the current body of scholarly work falls short in providing a thorough examination of the key aspects related to architectural and structural design for these environmentally sustainable towers. In an effort to bridge this knowledge gap and deepen our comprehension of the evolving worldwide trends, this research delved into data collected from 55 case studies conducted across the globe. The primary findings unveiled the following: (1) Europe, particularly Nordic countries, stood out as the region boasting the highest number of high-rise residential timber buildings, with North America and the United Kingdom following suit; (2) central cores were the prevailing choice for the core configuration, with the peripheral type following as the second most common option; (3) prismatic forms were the most commonly favored design choices; (4) widespread prevalence of employing pure timber was observed, followed by timber and concrete composite combinations; and (5) structural systems were predominantly characterized by the utilization of shear walled frame and shear wall systems. This research aims to reveal the current attributes of high-rise residential timber buildings, with the expectation that it will offer architects valuable knowledge to assist and steer them in planning and implementing forthcoming sustainable projects within this domain.

Uncertainty propagation in the simulation of a nuclear power plant operational transient

With the continuous deployment of various intermittent energy sources on the grid there is an increasing opportunity for nuclear reactors to perform power maneuvers which can help alleviate issues related to supply oscillations during some periods of high renewable output. While utility specific codes can model such transients for safety assessments, there is a need to increase confidence in the application of these codes and to quantify the capabilities and accuracies of models in predicting these transients. In this work a power maneuver from 100 % full power to 59 % full power for a large CANDU reactor was studied using the TRACE-PARCS toolset. The work was computationally expensive as it examined both the effects of i) nuclear data library uncertainty which requires re-generation of the few-group cross sections and regeneration of an equilibrium core using 4 years of synthetic fuelling, and ii) initial core burn-up distribution involving the simulation of online fuelling operations over a period of 1400 days.The figures of merit considered in this work include changes in the average liquid zone controller fill level, individual channel powers, and the timing of adjuster bank withdrawals and reinsertions. Amongst the 100 s of simulated transients, the average time between adjuster bank withdrawals to override the Xenon transient and absolute standard deviations in these timings were found to be consistent between different nuclear datasets. The observed standard deviations were small, suggesting that the sensitivity to both nuclear data and initial core configuration is relatively small for both the adjuster withdrawal phase and the reinsertion phase. The contributions to total uncertainty due to both the core initial conditions and the nuclear data uncertainty were determined. During the early phase of the transient (i.e., adjuster withdrawals) nuclear data uncertainty and initial condition uncertainties were found to contribute nearly equally to total uncertainty, with slightly larger contributions due to nuclear data uncertainty. For adjuster bank reinsertions later in the transient it was observed that the contribution to total uncertainty by initial condition uncertainty was on average twice that of nuclear data uncertainties.The transients were compared to an actual power maneuver in a ∼900 MW CANDU reactor. In all cases, the model’s behaviour, while qualitatively correct, systematically over-predicted the time durations between adjuster movements and this difference exceeded the envelope of simulations that account for nuclear data and initial core configuration. Sensitivity studies performed to investigate the discrepancies suggest that additional refinements to the RRS emulator used in this work are required to match the station RRS more closely and that the transient evolution is highly sensitive to the initial excess reactivity in the core, which was observed to be lower in the station than in the TRACE simulations. Based on the simulation results the combined impact of the emulator responses, initial average zone levels, and incrementals modelling have a larger uncertainty than those related to nuclear data and initial core burnup distribution.

Effect of Protactinium-231 (Pa-231) Addition on Effective Multiplication Factor Value of ThN-U233N Fueled PWR Reactor

This study aims to determine the optimum percentage of addition of protactinium-231 in a ThN-U233N fueled PWR reactor.In ThN-U233N, uranium-233 is used as the fissile material. Pa-231 as burnable poisson is added to ThN-U233N fuel to reduce the keff value. In this research conducted benchmarking keff values ​​of OpenMC and SRAC codes, homogeneous and heterogeneous core configurations, and the addition of Pa-231 in ThN-U233N fuel. Neutronic analysis was performed using the OpenMC code. In the homogeneous core configuration, the enrichment percentage of U-233 is varied by 1%-15%. Meanwhile, the heterogeneous core configuration uses 3 variations of ring geometry and fuel. The results of the benchmarking of the OpenMC and SRAC code keff values ​​show a maximum error of 1,906%. The homogeneous core configuration produces the optimum value for U-233 enrichment of 3%. Meanwhile, the optimum value of the heterogeneous core configuration is achieved in ring geometry F1 = F2 = F3 = 3 rings with enrichment of U-233 at F1 = 0,5%, F2 = 3%, F3 = 5,5% and addition of Pa-231 of 1.5%. The optimum calculation results has an excess reactivity value 8.37%.

Defining a core configuration for human centromeres during mitosis

The centromere components cohesin, CENP-A, and centromeric DNA are essential for biorientation of sister chromatids on the mitotic spindle and accurate sister chromatid segregation. Insight into the 3D organization of centromere components would help resolve how centromeres function on the mitotic spindle. We use ChIP-seq and super-resolution microscopy with single particle averaging to examine the geometry of essential centromeric components on human chromosomes. Both modalities suggest cohesin is enriched at pericentromeric DNA. CENP-A localizes to a subset of the α-satellite DNA, with clusters separated by ~562 nm and a perpendicular intervening ~190 nM wide axis of cohesin in metaphase chromosomes. Differently sized α-satellite arrays achieve a similar core structure. Here we present a working model for a common core configuration of essential centromeric components that includes CENP-A nucleosomes, α-satellite DNA and pericentromeric cohesion. This configuration helps reconcile how centromeres function and serves as a foundation to add components of the chromosome segregation machinery.

Imaging multiple magnetized anomalies by geomagnetic monitoring

The presence of magnetized anomalies in the shell of the Earth interrupts its geomagnetic field. We consider the inverse problem of identifying the anomalies by monitoring the variation of the geomagnetic field. Motivated by the theoretical unique identifiability result in [7], we develop a novel numerical scheme of locating multiple magnetized anomalies. In our study, we do not assume the source that generates the geomagnetic field, and the medium configurations of the Earth's core and the magnetized anomalies are a-priori known. The core of the reconstruction scheme is a novel imaging functional whose quantitative behaviours can be used to identify the anomalies. Both rigorous analysis and extensive numerical experiments are provided to verify the effectiveness and promising features of the proposed reconstruction scheme.

Experimental investigation on impact behavior of curved sandwich composites with chiral auxetic core

The purpose of this study is to evaluate and compare the capability of impact energy absorption of the sandwich panels with various chiral auxetic cores. To this end, flat and curved panels were subjected to impact testing at varying energy levels. Glass fiber-reinforced epoxy composites and PLA material were used as the skins and core of the examined sandwich panels, respectively. The face sheets were produced by the hand-layup method and the auxetic cores with tetrachiral, anti-tetrachiral, and hexachiral configurations were printed using a 3D printer. The wall thickness, node diameter, and ligament length of the cells, as well as the core thickness, were kept constant for all the studied core structures. Flat and curved sandwich panels were obtained by combining the skins and cores produced in flat, 100 mm, 125 mm, and 160 mm radii of curvature with the epoxy used in skin production. Drop weight tests were carried out at impact energies of 10, 25, and 80 J. The contribution of the auxetic core configuration and panel curvature to the impact behavior of the sandwich panel was evaluated by examining the relationships between contact forces and deflection and by the analysis of the energy absorption and failure mode. The comparative evaluations showed that the auxetic core structure and the curvature of the panel have a significant effect on the impact properties of the sandwich panels. It was also observed that the use of tetrachiral cores could be the ideal design option for flat panels loaded at the perforation energy level. For curved panels, it was determined that the use of a hexachiral core configuration was advantageous in terms of more energy absorption capability, while the use of an anti-tetrachiral core structure was more effective in terms of specific energy absorption.

A STUDY ON THE POWER VARIATION OF FUEL SUBASSEMBLIES CLOSER TO THE SOURCE SUBASSEMBLY OF THE 40MWT FBTR CORE

Fast Breeder Test Reactor (FBTR) which is a loop type, sodium cooled fast reactor, is one of the high flux - high temperature reactor in India with design power of 40 MWt (13.2 MWe). The design target power of 40 MWt was achieved with a core configuration with 68 Mark I (MK I) fuel subassemblies. A study has done to evaluate the variation in the power of fuel subassemblies which are closer to the source subassembly. Source subassembly in FBTR is a gamma neutron source (Sb2O3-Be) located in (05, 28) location. The study found that the presence of the source subassembly increases the power of the neighbouring fuel subassemblies. The variation in power due to the source subassembly is found to be 10% for fuel subassemblies in (05, 29) location and for other fuel subassemblies in 3rd, 4th & 5th ring, it is within 3.5%. The estimated LHR and power of the fuel subassemblies closer to the source subassembly are well within the permissible limits.

Improved Genetic algorithm for fuel loading optimization of the DNRR with HEU fuel

This paper investigates the performance of genetic algorithm (GA) with improved selection techniques, i.e. Tournament and Roulette Wheel, applied to in-core fuel management of the Dalat nuclear research reactor (DNRR). Numerical calculations have been performed based on the DNRR core with 100 HEU fuel bundles. The optimal fitness function was chosen to maximize the keff and minimize the power peaking factor. The statistical analysis using Mann-Whitney test shows that the performance of GA with Tournament selection is advantageous over the Roulette Wheel selection in the ICFM problem of the DNRR. The optimal core configurations obtained with the improved GA methods have the keff values greater by about 500 pcm, and the PPF lower by about 4.0% compared to the reference core.

Experimental and numerical study of effecting core configurations on the static and dynamic behavior of honeycomb plate with aluminum material

The sandwich panel incorporated a honeycomb core, a widely utilized composite structure recognized as a fundamental classification of composite materials. Comprised a core resembling a honeycomb, possessing thickness and softness, and is flank by rigid face sheets that sandwich various shapes and materials. This paper presents an examination of the static and dynamic analysis of lightweight plates made of aluminum honeycomb sandwich composites. Honeycomb sandwich plate samples are 300 mm long, and 300 mm wide, the heights of the core have been varied at four values ranging from 10 to 25 mm. The honeycomb core is manufactured from Aluminum material by using a novel technique namely resistance spot welding (RSW) instead of using adhesive material, which is often used when an industrial flaw is detected. Numerical optimization based on response surface methodology (RSM) and design of experiment software (DOE) was used to verify the current work. A theoretical examination of the crashworthiness behavior (maximum bending load, maximum deflection) and vibration attributes (natural frequency, damping ratio, transient temporal response) of honeycomb sandwich panels with different design parameters was also carried out. In addition, the finite element method-based ANSYS software was used to confirm the theoretical conclusions. The findings of the present work showed that the relationship between the natural frequency, core height, and cell size is direct. In contrast, the relationship between the natural frequency and the thickness of the cell wall is inverse. Conversely, the damping ratio is inversely proportional to the core height and cell size but directly proportional to the thickness of the cell wall. The study indicates that altering the core height within 10–25 mm leads to a significant increase of 82 % in the natural frequency and a notable decrease of 49 % in the damping ratio. These findings are based on a specific cell size value of 0.01 m and a cell wall thickness of 0.001 m. Also, the results indicate that for a given set of cell wall thickness and size values, an increase in core height from (0.01–0.025) m, leads to a reduction of the percentage of maximum response approximately 76 %. Conversely, the increasing thickness of the wall of cell wall, ranging 0.3–0.7 mm with a constant core height equal to 0.015 m, resulted in a de crease of maximum transient response by 7.8 %.

An algorithm for solving the equations of the Nodal Expansion Method in parallel using GPU

An Algorithm for Solving the constitutive equations of the fourth-order Nodal Expansion Method (NEM) with quadratic transverse leakage in parallel using GPU has been proposed. This algorithm was implemented on the GPU using the CUDA language, resulting in a calculation program called Cuda_NEM. The results obtained with the Cuda_NEM program were compared to those obtained with the CNFR code for three benchmarks available in the literature. From the results obtained, it can be concluded that the calculations performed with the Cuda_NEM program are as accurate as those of the CNFR code. Furthermore, it was found that the proposed algorithm was able to reduce the execution time compared to CNFR when simulating multiple core configurations simultaneously. This means that the proposed algorithm and the developed calculation program have shown promise for use in the optimization process of nuclear fuel reload patterns, where a large number of evaluations of different core configurations must be performed during the process.

Low‐velocity impact response and post‐impact assessment of self‐healing composites with different stacking configurations of core–shell nanofibers

AbstractThis work investigates the low‐velocity impact (LVI) and self‐healing behavior of carbon fiber composite laminates interlaced with electrospun polyacrylonitrile core–shell nanofibers (PAN@CFRP). The main goal is to investigate the influence of different stacking configurations of core–shell nanofibers on the impact resistance and self‐healing properties of composite laminates. To achieve the purpose, three different stacking configurations were designed and tested alongside virgin specimens. The damage mechanism and self‐healing of laminates following LVI were determined using ultrasonic C‐scan and cross‐sectional microscopy examinations. At an impact energy of 14.1 J, the flexural strength of the post‐healing PAN‐3@CFRP specimen reached 95.0% of the initial value, whereas at an impact energy of 21.8 J, severe impact damage was observed in the laminates with different configurations. Among the laminates, the PAN‐1@CFRP specimen had the highest flexural strength after healing, which reached 80.1% of its pre‐impact strength. As observed, the impact resistance and self‐healing capacity of composites could be significantly enhanced by optimizing the distribution configuration of core–shell nanofibers for various impact energies.Highlights The introduction of electrospun core–shell nanofibers has not significantly compromised the mechanical properties of the composites, but rather enhanced their toughness. The addition of core–shell nanofibers significantly enhances the impact resistance of the composites and imparts excellent self‐healing properties to the material. The flexural strength of impact‐damaged specimens with different stacking configurations can be restored up to 95% of the undamaged specimen after repair treatment. Significantly improved impact resistance and self‐healing ability of laminates by optimizing the distribution configuration of core–shell nanofibers between composite layers.

Developing structural sandwich panels for energy-efficient wall applications using laminated oil palm wood and rubberwood-based plywood/oriented strand board

In this work, a new type of structural sandwich panels made with laminated oil palm wood core and rubberwood-based oriented strand board (OSB)/plywood faces were introduced for energy-efficient wall applications in Thailand. Effect of the manufacturing process and material parameters including adhesive content (250 g/m2 and 500 g/m2), core configuration (cross or parallel laminated oil palm lumber) and density (low and medium) and face material type (rubberwood-based OSB/plywood) on panel’s properties were explored. The panels were produced using two-component polyurethane adhesive and a constant clamping pressure of 0.6 MPa. Adhesive content of 250 g/m2 was found to be sufficient for gluing all layers, with wood failure percentage of more than 80% as required by the standard. In-plane dimensional stability of the panels was mainly affected by the core configuration; it was better for cross laminated oil palm wood core sandwich panel. Higher core density resulted in increased density, thermal conductivity and compressive strength in the major direction but lower thermal resistance of the panel. The plywood face sandwich panels provided slightly higher compressive strength than OSB face sandwich panel, and their failure mechanisms were also different. The heat loss of these panels was about one-third of concrete and brick walls, hence, they can provide better insulation for indoor space. Based on the measured thermal conductivity, it was expected that these panels would pass the energy criteria according to Building Energy Code of Thailand. Thus, from the energy saving and sustainability perspectives, these panels can potentially be used as energy efficient wall panels for buildings, not only for Thailand but also for other tropical countries, where the oil palm wood and rubberwood resource is available.

Human body cholesterol detection based on a photonic crystal fiber sensor within a hollow octagonal core configuration

Human body cholesterol detection based on a photonic crystal fiber sensor within a hollow octagonal core configuration

Multiphysics assessment of a PWR-type SMR core using Spherical Cermet fuel through a neutronic and thermohydraulic coupled study

In this paper, a multiphysics assessment of the performance of a PWR-type SMR core using Spherical Cermet Fuel is carried out, through a coupled neutronic-thermohydraulic study using Serpent and Ansys CFX codes. The most important results related to the core performance are compared with those obtained when TRISO fuel is used. Correlations (Cp, k) were developed as function of temperature for the fuel region, which are unique and specific for the fuel of this study. The results obtained show that the neutronic-thermohydraulic coupled calculation converges from the fourth iteration, with Keff being the convergence indicator that converges more slowly. An extended fuel cycle of 1448 days was achieved with a uniform power distribution. With this new core configuration, a lower production of plutonium isotopes was obtained. Temperatures below the safe operation limit were obtained in all the studied zones, as well as basic negative safety parameters such as fuel temperature and moderator temperature coefficients, and the full coolant void coefficient.