Panel Dimensions Research Articles

Optimization of graded and partial metamaterial treatments for enhanced broadband sound insulation in partition panels

Resonant metamaterials can achieve unprecedented vibroacoustic attenuation in lightweight partition panels through small resonators attached on a subwavelength scale. Conventional metamaterial treatments are effective only in a narrow band and typically cover the entire panel surface, posing important challenges for industrialization due to manufacturing and cost constraints. To address these issues, in this study we propose graded and partial metamaterial treatments, which are selectively distributed where they are the most effective, avoiding unnecessary coverage, and include a spatially varying resonance frequency for broadband effectiveness. The related design challenges are tackled by developing a numerical methodology that simultaneously optimizes the distribution and the grading of the treatment. The optimization objective is to maximize the broadband diffuse sound transmission loss (STL) of the metamaterial panel, while constraining the maximum fraction of treated area. Leveraging effective medium modelling, the approach efficiently incorporates local changes in the effective mass density of the metamaterial panel to represent partial treatments. Different design cases are considered for different target bands and panel dimensions. Results demonstrate that graded partial metamaterial treatments can achieve broadband improvements with a limited treated area, effectively suppressing the STL dips due to the modes of the host panel and to coincidence effects.

Proposed correction to the Gamma method for estimating the bending stiffness of CLT panels

Engineered wood products, such as Cross Laminated Timber (CLT), have been widely used in civil construction. Standard calculation methods, like the Gamma method commonly used in structural design, estimate the bending stiffness of elements. However, these methods are based on one-dimensional solids (bar elements), which can be limiting. This limitation may result in inaccurate estimates, especially when the panel's dimensions, measured in the median plane, significantly differ by an order of magnitude. In this research, a parametric study was carried out using the finite element method (three-dimensional approach), varying the panel's dimensions (width and length), the layers' thickness, and the number of layers (cross-section height), and adopting elastic properties considering either the wood's orthotropy or the rolling shear estimation (108 numerical simulations in all). Based on the parameterization, multiple variable regression models were used to establish a correction coefficient to be incorporated into the Gamma method to improve its accuracy in estimating bending stiffness. Therefore, the single adjusted equation (considering the wood's orthotropy) showed values closer to the numerical ones (MAPE = 0.95 %, RMSE = 2.96 × 1011 N⋅mm2, and CV = 1.60 %) than those obtained by the Gamma method (MAPE = 2.13 %, RMSE = 7.47 × 1011 N⋅mm2, and CV = 4.04 %).

Accuracy compensation method with the combined dissimilar measurement devices for enhanced measurement quality: a digital aircraft assembly technology

PurposeThe pivotal aspect of aircraft assembly lies in precise measurement accuracy. While a solitary digital measuring tool suffices for analytical and small surfaces, it falls short for extensive synthetic surfaces like aircraft fuselage panels and wing spars. The purpose of this study is to develop a “combined measurement method” (CMM) that enhances measurement quality and expands the evaluative scope, addressing the limitations posed by singular digital devices in meeting measurement requirements across various aircraft components.Design/methodology/approachThe study illustrated the utilization of the CMM by combining a laser tracker and a portable arm-measuring machine. This innovative approach is tailored to address the intricate nature and substantial dimensions of aircraft fuselage panels. The portable arm-measuring machine performs precise scans of panel components, while common points recorded by the laser tracker undergo coordinate conversion to reconstruct the fuselage panel’s shape. The research outlines the CMM’s measurement procedure and scrutinizes the data processing technique. Ultimately, the investigation yields a deviation vector matrix and chromatogram deviation distribution, pivotal in achieving enhanced measurement precision for the novel CMM device.FindingsThe use of CMM noticeably enhances fuselage panel assembly accuracy, concurrently reducing assembly time and enhancing efficiency compared to conventional measurement systems.Practical implicationsThe research’s practical implication lies in revolutionizing aircraft assembly by mitigating accuracy issues through the innovative digital CMM for aircraft synthetic structure type product (aircraft fuselage panel). This ensures safer flights, reduces rework and enhances overall efficiency in the aerospace industry.Originality/valueIntroducing a new aircraft assembly accuracy compensation method through digital combined measurement, pioneering improved assembly precision. Also, it enhances aerospace assembly quality, safety and efficiency, offering innovative insights for optimized aviation manufacturing processes.

P2PE: A finite element formulation for panel-to-panel cross-laminated timber connections

This paper presents a new multi-spring finite element formulation called P2PE that simulates the cyclic behavior of panel-to-panel Cross-Laminated Timber (CLT) connections. The formulation comprises five types of uncoupled linear/nonlinear springs representing the fasteners and contact between panels. For instance, the in-plane fastener behavior is simulated with a co-rotational spring and the Modified Richard–Abbott (MRA) model, which is adapted to account for the asymmetry, pinching, degradation, and low-cycle fatigue of timber connections. The model was implemented into ANSYS through user-element/materials, including all computer implementation steps, and can be freely downloaded. The model's response and sensitivity were studied in three demonstrative CLT diaphragms, and it was validated at the connection and assembly stage with benchmark tests. In the first stage, the fastener model was verified with four cyclic CLT connections, while in the second stage, the model was validated with three medium-to-large scale CLT assemblies. The model accurately predicts the stiffness, strength, deformation, slip, and failure mechanisms of both stages. Finally, a parametric analysis of in-plane bending CLT diaphragms was assessed by varying their panel dimensions. This analysis demonstrated that diaphragms with slender panels have larger capacities, fastener energy dissipation, and shear slips but lower ductilities than shorter ones.

A 2-dimensional guillotine cutting stock problem with variable-sized stock for the honeycomb cardboard industry

This paper introduces novel mathematical optimisation models for the 2-Dimensional guillotine Cutting Stock Problem with Variable-Sized Stock that appears in a Spanish company in the honeycomb cardboard industry. This problem mainly differs from the classical cutting stock problems in the stock, which is considered variable-sized, i.e. we have to decide the panel dimensions, width, and length. This approach is helpful in industries where the stock is produced simultaneously with the cutting process. The stock is then cut into smaller rectangular pieces that must meet the customers' requirements, such as the type of item, dimensions, demands, and technical specifications. Furthermore, in the problem tackled in this paper, the cuts are guillotine, performed side to side. The proposed mathematical models are validated using real data from the company, obtaining results that drastically reduce the produced material and leftovers, reducing operation times and economic costs.

Thermoelectric-Based Radiant Cooling Systems: An Experimental and Numerical Investigation of Thermal Comfort

Researching novel cooling and heating technologies as alternatives to conventional vapor-compression refrigeration cycles has received growing attention in recent years. Thermoelectric (TE) systems rank among promising emerging technologies within this category. This paper presents a comprehensive investigation, utilizing numerical modeling and analysis via COMSOL Multiphysics along with experimental validation, to evaluate the performance of a radiant cooling ceiling panel working on thermoelectric principles. Performance metrics are based on thermal comfort levels within the designed test chamber. The system comprises a rectangular test chamber (~1.2 m × 1.2 m × 1.5 m) with a centrally positioned ceiling panel (dimensions: 0.6 m × 0.6 m × 0.002 m). Four TE modules are attached on top of the ceiling panel, facilitating effective cooling to regulate the ceiling temperature to the desired setpoint. The resultant lower ceiling temperature enables heat exchange within the chamber environment via radiation and convection mechanisms. This study examines the time-dependent variations in mean radiant temperature and operative temperature under natural convection conditions, with comfort level assessment carried out using the PMV method according to ASHRAE Standard 55. An experimental chamber is built to validate the numerical model by performing experiments at various ceiling temperatures. Design challenges are discussed in detail. The results of this investigation offer valuable insights into the anticipated thermal comfort achievable through TE-based radiant cooling systems across various operating conditions.

Optimizing performance of water-cooled photovoltaic-thermal modules: A 3D numerical approach

To evaluate and improve the efficiency of photovoltaic solar modules connected with linear pipes for water supply, a three-dimensional numerical simulation is created and simulated via commercial software (Ansys-Fluent). The optimization utilizes the principles of the 1st and 2nd laws of thermodynamics by employing the Response Surface Method (RSM). Various design parameters, including the coolant inlet velocity, tube diameter, panel dimensions, and solar radiation intensity, are systematically varied to investigate their impacts on energetic and exergitic efficiencies and destroyed exergy. The relationship between the design parameters and the system responses is validated through the development of a predictive model. Both single and multi-objective optimizations are performed using the predictive model to optimize the thermal and electrical productivity under different scenarios. The findings indicate the significance of the thermal exergy effectiveness, as evidenced by its low P-value for all solar system responses, indicating its crucial role in the predictive model. For single-objective optimization, the desirability is equal to 1 in cases where only heat transfer efficiency, whole energy effectiveness, or thermal exergy efficiency is maximized or only destroyed exergy is minimized. The improvements in energy and exergy efficiencies range from 3.55% to 69.13%, with the amount of destroyed exergy reduced by 81.47% compared to the base case. For multi-objective optimization, desirability values exceeding 0.829 and 0.655 are obtained for single and multi-objective scenarios, respectively, indicating that the expected performance is within desirable limits. The findings provide valuable insights for designing high-efficiency photovoltaic/thermal systems and addressing their challenges and limitations.

A contribute to the development of a design procedure for space-born sandwich panels with CFRP skins and an aluminum core

Composite sandwich panels have a vast heritage and are commonly employed in various fields. The space industry is not an exception and often space structures and experiments use this type of panels. This paper represents an effort toward the development of a design procedure for space-born sandwich panels. The here-presented work has been performed on a real test case: the structural sandwich panel of a scientific space mission. In this preliminary phase, classical methodologies were used to ensure the satisfaction of the mechanical requirements and for the minimization of the panel mass and dimensions. Tools such as Finite Element (FE) were employed to help with the design. Increasingly detailed models were developed and used to design the space panels. In addition, this work describes the future roadmap of the project.

Dynamic Instability Characteristics of Spherical Panels Subjected to linearly varying In-plane Loading

The present paper reports the parametric instability phenomenon of spherical shell panels under linearly varying harmonic load employing finite element technique. An isoparametric curved element with eight nodes is considered in the formulation.. The sanders’ theory is used to model the spherical panel incorporating the properties of transverse shear and rotary inertia. A computer programme is created based on the formulation to carry out all essential calculations.The correctness of the formulation is established by comparing with results available in the literature.The impact of different parameters such as load factors, shallowness ratio on the instability regions of spherical panels with three support conditions such as SSSS (all edges simply supported), CCCC (all sides clamped) and CFCF (two opposite edges clamped and other two edges free) are studied. The study demonstrates that the parametric instability behavior of the spherical shell panels is significantly influenced by its shallowness parameter, boundary conditions and type of loads. These results will help the designers for deciding the dimensions of the spherical panels exposed to linearly varying periodic load at the time of the preliminary design.

Design of solar cell using mirror, cooling, double axis, and solar tracking

Fossil energy sources are dwindling. It is necessary to develop alternative energy sources for future energy. The solar cell is an alternative energy that can be used in Indonesia. The current challenge is utilizing solar panels for the best possible power production. This research gives the solution to design an increase in solar cell output power by using mirrors, cooling, and a double-axis solar tracking control system. The results show that using a mirror, cooling, and double-axis solar tracking produces optimal output power with a current and power are 2.43 amperes and 40.3 watts, respectively. Meanwhile, several factors can affect this solar panel's efficiency. Specifically, the amount of solar radiation that the solar panel can receive depends on the climate on the day and location of the research and the solar panel's dimensions.

Semi-analytical study of buckling response for grid-stiffened panels during creep age forming

The elastic–plastic buckling response of panels with grid stiffeners during creep age forming (CAF) has been studied using a semi-analytical method in this research. A simplified model for panels with multiple grid stiffeners under bending has been established and the effective width has been applied to consider the flexible skin effect and multiple stiffener effect. In the semi-analytical method, the equilibrium equation for the simplified model has been solved via differential quadrature method to acquire the buckling stress of grid-stiffened panels, using deformation theory (DT) and incremental theory (IT) of plasticity. The results with IT show good agreements with both the published experimental and non-linear FE results, demonstrating its effectiveness. Based on the method, the effects of geometric dimensions of grid-stiffened panels, multiple stiffeners and temperature on buckling response in the elastic and plastic regions have been studied. It is found that the transverse stiffener provides a 13.9% higher buckling stress of grid-stiffened panels than blade-stiffened panels, and buckling may occur in the heating stage during CAF. The proposed semi-analytical method based on IT provides accurate predictions of buckling stress during either CAF or cold forming, which can guide the parameter optimisation of grid-stiffened panels in design.

Large deflection resistance and fracture of panels subjected to the lateral penetration

This paper is concerned with the plastic behaviors of a rigid indenter into a typical ship side panel with analytical and numerical studies. The focus is on a more comprehensive framework where panel dimensions, indenter shapes, and material failure properties are allowed to change when predicting panel failure initiation and the deformation resistance force. Therefore, concise analytical solutions are derived by the plastic membrane and fracture based on a global stability criterion for large deflection. The power curve fitting to the analytical solutions brings out the brief-expression where the influence of geometric and material parameters is present clearly. In addition, the shape factor CS is introduced to illustrate the indenter's sharpness and enable the semi-analytical solutions to deal with the indenter with various geometries:Experimental results of specimens with a range of dimensions punched by indenters presented in the previous work are used to validate the proposed analytical solutions. Numerical simulations are supplemented and demonstrate that the penetration to fracture initiation and the large deflection resistance are sensitive to specimen dimensions and shape and can be predicted accurately by the proposed solutions. Moreover, the applied fracture criterion in analysis considered the change of the geometric and material properties shows consistency with the numerical observations that panel fails by localized necking. By the extension based on the deformation assumption, the corrected procedure enables the prediction of stiffened panels.

Thick panel origami for load-bearing deployable structures

Origami-based deployable structures are of great interest as they can be manufactured and folded from thin flat sheets of material. However, the thin nature of origami panels results in a weak structural form at configurations close to unfolded or developed geometries. It, therefore, limits the functionality of such structures in applications involving load-bearing and full-unfolding. In this work, we show that by using the thick panel versions of the origami structures, one could obtain better load-bearing characteristics, especially at configurations close to the fully-unfolded geometries obtained through deployment. Specifically, we compare and contrast the geometry and structural behavior of a Yoshimura origami structure made from thin and thick panels. We present and implement a geometric framework to calculate the nodal coordinates of tessellated thick Yoshimura structures with arbitrarily specified panel dimensions and folded states. We discuss the structural modeling of a three-cell Yoshimura at a meter length scale and perform structural analysis at various folded configurations. We demonstrate the suitability of the thick panel structure over the thin panel version for resisting applied loads at configurations close to the fully-deployed state. The results indicate that employing thick panel geometries could enable the use of origami-based deployable structures at large length scales, especially for applications involving load-bearing.

The Influence of Drop Panel's Dimensions on the Punching Shear Resistance in Ultra-High-Performance Fiber-Reinforced Concrete Flat Slabs

Ultra-high performance fiber reinforced concrete (UHPFRC) is a high-performance cementitious material with enhanced tension, compression, and toughness, strengths in the post crack region with high ductility, toughness, and durability. The companies prefer to use it to construct highly durable structures such as high-rise buildings, towers, and bridges. In addition, the thickness of the flat slab produced by UHPFRC might be thinner than the conventional concrete. One problem that has always been a concern in a flat slab is the punching shear failure since this failure is brittle and occurs suddenly without any previous notice. Besides, the position of the critical section for punching shear could be changed based on the thickness of the drop panel and the inclusion of fiber in the concrete. This paper highlights the effect of drop panels dimension on the punching shear resistance in UHPFRC flat slabs. The four two-way interior UHPFRC supported flat slab panels, consisting of one control flat slab without drop panels and three-flat slabs with different sizes of drop panels (10.5%,14.5%, and 19%) of the total area of slab drop panels, tested under punching load. Results indicated that the covered area of flat slabs by drop panel around 10.5% improved punching load up to %20 and 37% at the crack and ultimate loads. Furthermore, the test results show that the efficient covered area for resisting punching was 10.5% of the total area of the tested slab. Besides, the deflection values, strain in reinforcement and concrete, rotation at supports, and the inclination angles of cracks were improved due to the stiffness enhancement in the flat slabs.

Reconstruction of hydronic radiant cooling panels: Conceptual design and numerical simulation

Thermal contact resistances are detrimental to the heat transfer of a radiant cooling panel with the pipe-plate structure, thereby reducing its cooling capacity. Therefore, the pipe-plate structure of traditional radiant cooling panels is reconsidered in this study. Being analogous to the structures of liquid cooling plates, the radiant cooling panels with integrated flow channels are constructed. The effects of panel materials, flow channels, and dimensions on the thermal and hydraulic performance of the reconstructed radiant cooling panels are detailedly discussed based on numerical calculations. The relationship between temperature uniformity, cooling capacity, and condensation prevention of radiant cooling panels is described. The numerical results show that the inlet temperature of cold water of the restructured radiant cooling panels can be increased by about 4 °C compared to that of a traditional one with the pipe-plate structure when the same 80.1 W/m2 cooling capacity is provided. This study is conducive to a better understanding of radiant cooling panels.

Несуча здатність сонячних панелей, встановлених на похилих дахах будівель на території України

The growing shortage of energy resources encourages the more active usage of energy-efficient technologies, in particular the use of solar panels to power low-rise buildings. The aim of the work is to establish the maximum allowable spans of solar panels taking into account climatic loads in different regions of Ukraine. According to the previously developed method, the bearing capacity of solar panels made of tempered glass with a thickness of 3 mm at a ratio of length to span of the panel equal to 2.0 was performed. The panels are installed at a height of up to 20 m from the ground level at angles of inclination to the horizon due to the design of the roofs. Characteristic values of snow cover weight, ice weight and wind pressure were adopted based on the results of the administrative-territorial zoning of Ukraine previously performed by the authors. Each administrative region corresponds to the characteristic values of the loads set in the safety margin with a security level of 0.95. This approach allowed to obtain the dependences of the maximum allowable span (smaller size) of the solar panel from its angle of inclination to the horizon for all 25 regions. In all cases, the condition of rigidity was decisive, and the allowable spans of panels in Ukraine were obtained equal to 0.61… 1.10 m. The largest allowable spans are in the southern regions, and the smallest span - in the snowy regions of Ukraine. Changing the thickness of the panel leads to a proportional change in its allowable span. The developed recommendations allow to choose the type and dimensions of solar panels for installation on the hip roofs of buildings in each of the administrative regions of Ukraine. The allowable span of panels, the shape of which is closer to square, can be increased by repeating the calculations according to the aforementioned method.

Numerical analysis of lightweight concrete wall panels having a variation of dimensions and openings that were subjected to static lateral loads

Wall panels are non-structural parts of buildings that are considered dead loads. The mass of wall panels must be reduced to minimize earthquake risk and enhance structural resistance to lighter dead loads. This study used wall panel models that consisted of lightweight foamed concrete materials containing expanded polystyrene. The wall panels used in this study also had a variety of dimensions and reinforcements. The effect of openings on wall panel model performance was also investigated. This study aimed to analyze the performance of lightweight concrete wall panel models under static lateral loads applied until the ultimate condition. It was found that the load-deformation relation performs varying values of stiffness, strength, and ductility depended on the wall panel dimensions, reinforcements, and openings. A wall panel model with a height of 1000 mm that had length of 1500 mm and thickness of 60 mm with wire mesh and without openings achieved the highest ultimate stiffness and strength. The highest ductility was achieved by a wall panel model with openings, without wire mesh, with height, length, and thickness of 1500 mm, 1500 mm, and 40 mm, respectively. Diagrams of the deformations in this paper reflect the compressed and tensioned areas. The lefthand parts of all wall panel models without wire mesh were tensioned and had concentrations of deformation in those areas. The existence of openings also caused increased deformation due to less stiffness in the wall panel models.

Behavior of Steel Fiber Reinforced Concrete Panels under Surface Pressure

In this study, it is aimed to investigate the importance of the affecting parameters on the pressure–displacement relationship of steel fiber reinforced concrete panels. Among these parameters, panel thickness, panel dimensions, material type, and boundary conditions of the panels are the parameters that were examined. In this context, the effects of surface pressure on the steel fiber reinforced concrete panels were investigated. It was observed that as the thickness and the fiber ratio increased, the ultimate bearing capacity increased. It was determined that it may not be enough to support the panels only at the corner points, and intermediate supports are needed. As the support spacing decreased, the absorbed surface pressure increased. In addition, it was concluded that the increase in the amount of steel fiber in the concrete material increased the strength, deflection, and ductility values.

Development of mathematical models for predicting dimensional stability of furniture boards using the finite element method

An approach for predicting the properties of furniture boards made of common beech wood (Fagus sylvatica L.) based on the finite element method is proposed. It has been found that in the constructions of furniture panels made of beech wood, an orthogonal, cylindrical or transversal calculation scheme of anisotropy can be attributed depending on the dimensions of the furniture panels and the orientation of the fibers in the rails. A model of the physical and mechanical properties of monolithic or jointed slats made of beech wood during the finite element analysis of furniture boards based on the cylindrical coordinate system of the anisotropy of constant elasticity is proposed. It has been established that the practical use of the cylindrical anisotropy scheme when solving the problems of the mechanics of a rigid deformed body for the calculation of furniture boards made of beech wood is expedient when it is not possible to ignore the curvature of the annual layers, that is, when analyzing the dimensional stability of furniture boards and monolithic or jointed reibukaak made of beech wood with swelling and shrinkage. An applied methodology for calculating furniture boards made of beech wood has been developed, which makes it possible to take into account the peculiarities of the anisotropy of the physical and mechanical characteristics of the rails, taking into account their shrinkage and swelling when the temperature and humidity conditions of the environment change. The substantiation of new designs of furniture boards made of beech wood, which is based on the use of finite element analysis systems, allows identifying the shortcomings of these products at the conceptual stage of the project and correcting them before the start of production, taking into account the specified technical conditions. An optimal arrangement scheme of annual layers in adjacent slats of furniture panels made of beech wood is proposed, which ensures improvement of dimensional stability (reduction of gouging) of the structure while simultaneously reducing the stresses that arise when the humidity of the product increases during operation. Mathematical models are proposed that predict (describe) the strength and dimensional stability of furniture boards made of common beech wood. The developed model can be used for research and optimization of furniture boards of new designs according to the conditions of strength and deformability.

High-Speed Laser Beam Induced Current Imaging: A Complementary Quantitative Diagnostic Tool for Modules

High-resolution imaging techniques based on thermography, luminescence imaging, and laser beam induced current (LBIC) probe and inspect solar cells and correlate the observed inhomogeneities to the cell performance. The imaging methods get increasingly qualitative as the size scales from cell level to module dimensions, where several solar cells are connected in series, as in silicon panels. Electroluminescence (EL) imaging is a standard measure of inspecting solar panels and extensively utilized in the manufacturing assembly line. The complementary method of obtaining images from the LBIC scanning technique, however, is rarely utilized at large panel dimensions. We report strategies to implement LBIC imaging at module levels and procedures to analyze in terms of microscopic and circuit parameters. LBIC is inherently quantitative and well suited to identify microscopic defects, since it involves measuring local photo-current. We demonstrate that the contrast features from LBIC in a specific cell region are directly associated with the shunt resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R_{\text{sh}}$</tex-math></inline-formula> ) variation of that specific cell. Using a single diode equivalent circuit model, we show that the current contrast of the cell under study is purely a function of its <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R_{\text{sh}}$</tex-math></inline-formula> , and an effective load resistance that includes shunt-resistance of the other series-connected cells. The resulting LBIC-map along with EL then becomes a complete diagnostic tool to quantitatively map and identify the defects prevailing in a solar panel. We overcome the key issue of the slow speed of LBIC based imaging by a modified scan routine for rapid screening of large areas (2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\bf m}$</tex-math></inline-formula> by 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\bf m}$</tex-math></inline-formula> ) panels under 5 min, at high resolution.