Perforated Sheet Metal Research Articles

Formability prediction of perforated sheet metal by representative volume element and homogenized sheet models

Perforated sheet metal (PSM) can be formed with plastic deformation. Modeling a perforated model in finite element analysis requires domain discretization with many small elements, which can lead to significant computation time and cost. This study introduces a novel approach using representative volume elements (RVE) and homogenized sheet (HS) models as an efficient alternative for PSM analysis. The forming limit of the PSM was established by analyzing localized necking in RVE. The HS model in simulations of the limit dome height and Swift cup tests results were in good agreement with those from the computational intensive perforated sheet models.

Thermo-elastic vibration analysis and optimization of a nanoresonator composed of a coupled nanotube system for acoustic liner application using the hybrid deep neural network–based white shark algorithm

This study explores the potential of nanoresonator systems composed of coupled nanotubes with graphene nanoparticles for enhancing the performance of acoustic liners in aircraft engines. The objective of this study is to develop an analytical model and predict its behavior under various conditions. The acoustic liners consist of perforated metal sheets and honeycomb cavities, which are essential for noise reduction in aircraft engines. The model is tested for variations in natural frequency, mode number (m), size effects (e0a), viscous constant (C), temperature (T), localness factor (L), and stiffness constant (K). A hybrid deep neural network–based white shark algorithm (DNN-WSA) is used to predict and optimize the performance of nanoresonator-coupled nanotube systems. Four theories were compared, such as wave propagation theory, nonlocal elasticity theory, polynomial eigenvalue approach, and governing equations with respect to natural frequencies in nanoresonator-coupled nanotube systems. The wave propagation theory yielded the lowest natural frequency, which was selected for detailed analysis. The optimized values of size effect of 2 nm, temperature of 5 K, and frequency of 1.971975 THz were obtained. When C = 0.3, K = 10, T = 300, and L = 10×e−9, the root mean square error (RMSE) value is 0.8421, which indicates improved predictive performance as it continues to decrease. The study’s findings showed that changes in viscous constants impact natural frequencies, while size effects have a minor influence. Temperature variations also affect natural frequencies, with higher temperatures leading to higher frequencies. The optimized model demonstrates enhanced predictive performance, which contributes to a better understanding of nanoresonator systems and their application in noise reduction for aircraft engines.

Statistical Investigation of the Reproducibility of Stack Components in a PEM Water Electrolyzer

To achieve homogeneous conditions throughout a single cell of a stack and within a stack and furthermore within several stacks, the components assembled in a stack should be reproducible to achieve a homogeneous performance. To evaluate how reproducible the stack components are, the porous transport layers, the expanded metals sheets, the perforated metal sheets, and the flow field plates from a 5-cell stack were examined.Eight samples were cut out of each of the 450 cm² layers, and a height profile (area: 10 x 10 mm) was recorded using a laser scan. From the height profile, the roughness values Ra (arithmetic average) and Rz (maximum peak to valley height) could be derived as well as the curvature of the samples (see Figure 1). Figure 1a) shows a contour plot of a perforated metal sheet. There is a height difference of up to 20 µm from the edge to the center of the sample. For the stack assembly this means an initial force is required to flatten the sheet before the actual compression of the stack takes place. Figure 1b) shows the roughness values Ra and Rz. The values vary within the sample (Ra: ± 3.8 µm, Rz: ± 5.7 µm) and throughout the samples (Ra: ± 1.4 µm, Rz: ± 2.5 µm). Further, the thickness of the components was measured, and the variation was calculated. In terms of stacking the components, as done in the stack, the best and worst case were calculated. The aim of this study was to determine input parameters for follow-up tests for the mechanical and electrical characterization of the components as especially the roughness of the components may have a significant impact on the contact resistance. Figure 1

Enhancing Air Traffic Management and Reducing Noise Impact: A Novel Approach Integrating Băneasa Airport with Otopeni RO Airport

Over the years, Bucharest’s Henri Coandă International Airport has registered a constant and high increase in air traffic, in terms of both passengers and aircraft movements. This paper presents a traffic diversion solution for the Otopeni RO airport, which aims to alleviate air traffic congestion by redirecting a proportion of the planes to the nearby airport at Băneasa. The primary challenge faced by diversion to Băneasa Airport is the proximity of residential areas to the runway at distances of less than 300 m, resulting in significant noise pollution issues. At Otopeni Airport, the main operators use aircraft equipped with CFM 56 turbo engines; therefore, this study begins with an evaluation of the noise directivity of a CFM aircraft engine via measurement. The data thus collected enabled the identification of the dominant frequencies in the acoustic spectrum of the engine noise. A resonant screen solution has been proposed as a solution for Băneasa Airport, emphasizing the importance of implementing solutions to address the noise pollution faced by those living near Băneasa Airport, due to its proximity to the residential area. Various configurations of perforated metal sheets with different perforation patterns were compared to the test performance of solid sheets to optimize noise absorption. Using the impedance tube tests to achieve the highest absorption coefficient, it was determined that the optimal distance between the perforated metal sheets and the resonant screen was 30 mm. Based on the CFM 56 turbo engine noise directivity and the impedance tube tests, a multitude of numerical simulations were conducted using the IMMI software (IMMI 2011). The simulations were performed for two scenarios with and without an acoustic barrier, accounting for the typical configuration of two engines on an aircraft. The results indicate a reduction of 15 dBA with the implementation of a 4-m-high acoustic barrier, in the case of a CFM 56 engine operating at full throttle while the aircraft is on the ground. Through numerical simulations, the optimized resonant screen demonstrated its potential to significantly reduce noise levels, thereby enhancing the overall acoustic environment and quality of life for the communities surrounding Băneasa Airport. The identified findings could serve as a basis for further research and the implementation of innovative solutions to manage air traffic and reduce the impact of aircraft noise in surrounding areas.

Coupled magnetic Mie resonances induced extraordinary optical transmission and its non-linear tunability

Dielectric metamaterials with low ohmic losses and resonating in the local magnetic mode are preferable for enhancing material non-linearity. Here, we propose and experimentally demonstrate broadband extraordinary electromagnetic transmission (EET) behavior, which is induced by the coupling of magnetic modes of two ceramic cuboids. It is shown that extraordinary electromagnetic transmission behavior through a perforated metal sheet with a subwavelength aperture can be achieved by exciting the first-order magnetic mode Mie resonant coupling of these cuboids. Our findings indicate that the transmission bandwidth and amplitude are dependent on the strength of coupling between the two ceramic cuboids. Additionally, we utilized non-linear effects within the dielectric cuboids to achieve tunable extraordinary electromagnetic transmission behavior. Our results are promising for developing non-linearly tunable microwave devices such as filters and modulators of their strong light-matter interactions.

A New Method to Develop Homogeneous and Heterogeneous Porous Micromodels Applicable to Enhanced Oil Recovery and Flow Visualization Experiments

AbstractIn this paper, a new method to fabricate micromodels having homogeneous and heterogeneous porous structures is reported to gain fundamental insight into the flow through porous media. The technique of microparticle image velocimetry (PIV) is used to map the pore-scale velocity field inside the micromodels. A thin perforated metal sheet composed of uniformly distributed circular holes is used as the master pattern, and the replica of the negative of this perforated sheet is transferred to a polydimethylsiloxane (PDMS) substrate using a method similar to the soft lithography. This method allows an efficient fabrication of micromodels having different porosity by adjusting and selecting the perforated sheets of different hole sizes. The prepared micromodels were tested for its applicability and reliability by carrying out the measurements of pore-scale velocity distribution using the micro-PIV technique. The experiments with micromodels with high porosity but different grain arrangements showed qualitative as well as quantitative differences in the velocity field. The pressure drop across the two ends of micromodel is also measured. The variation of pressure difference with the flowrate is found to be nonlinear with a significant effect on the patterns of micropillars. However, at low porosity, the variation of pressure difference with the flowrate is found linear and there is almost no influence of the micropillar patterns. The flow visualization measurements are also conducted with the dual porosity micromodels, and the flow patterns were examined by analyzing the velocity vector maps.

Material Modeling of Perforated Sheet Metals with Different Hole Arrangements by Homogenization Method

The homogenization method is effective for analyzing macroscopic mechanical properties from the substructure of a material. In perforated sheet metal, macroscopic mechanical properties depend on the pattern of hole arrangement. In this study, the macro–plastic properties of perforated sheets with 60° standard staggered and 90° square arrangements are modeled. Biaxial stress is applied to the unit cells given the periodic boundary condition, and the contours of equal plastic work are obtained. The yield surfaces of the perforated sheets on the tension–compression combined stress state are strongly affected by the hole arrangement. To model the yield surface, a yield function for the rotational symmetry peculiar to the perforated sheet is proposed. The yield surfaces are modeled using the CPB2006 yield function that takes into consideration tension–compression asymmetry. Also, a surface–interpolated differential hardening model is applied to model the changes of yield surfaces. The analysis results obtained using the modeled yield surfaces are compared with the experimental ones obtained on the uniaxial tensile and deep drawing tests. The results of both tests show good agreement.

Comparison of Daylight Performance in Three Different Sky Conditions for Various Window Shading Types

Building sector contributes 40% of total energy consumption. In line with this, passive design strategy should be taken as an essential consideration to bring occupants comfort both thermally and visually. Besides, related to human health, one of the factors that the designer is encouraged to fulfill is the proportional amount of daylight that penetrates the building’s room. The passive strategy to optimize the daylight performance can be approached both from the building orientation and the shading system. This paper will computationally compare the different shading systems from vertical and horizontal louver, perforated metal sheets, and expanded metal shading, aiming to investigate the desirable shading-related design solution for the given condition. The simulated room is virtually situated in three different sun positions: Birmingham, United Kingdom, Jakarta, Indonesia, and Sydney, Australia. The metrics used in this experiment are Useful Daylight Illuminance (UDI). The Rhinoceros and Grasshopper were used to model the intended simulated room, while Ladybug and Honeybee were used to undergo environmental analysis. The results show that the vertical louver LV performs better in the three regions than the rest three compared shading. The experiment results are expected to give an overview which of which is fit for the situation.

Magnetospectroscopy of terahertz surface plasmons in subwavelength perforated superlattice thin-films

Surface plasmons, the resonant oscillations of conducting electrons at the interface of negative and positive permittivity materials, pave the way for enhanced electromagnetic wave–matter interactions at a subwavelength scale. On the other hand, spin-dependent magnetotransport ushers an ingenious technology by inculcating electron spin to realize miniaturized, energy-efficient electromagnetic devices. Generally, magneto-resistive devices (viz., multilayer un-patterned magnetic–non-magnetic thin films) relying on magnetotransport mechanisms are not recognized for supporting surface plasmons toward enhanced electromagnetic interactions. However, an amalgamation of surface plasmons with spin-dependent magnetotransport can exploit magnetic (spintronic) degree of freedom in plasmonic devices. In this work, we propose a patterned superlattice (non-magnetic/ferromagnetic thin films) terahertz (THz) magneto-resistive device for supporting surface plasmons toward enhanced electromagnetic interactions. Magnetotransport dependent enhancement and dynamic magnetic modulation of resonant THz transmissions are experimentally demonstrated in subwavelength superlattice (Al/Ni) hole arrays for varying lattice parameters. Our experiments reveal that typical non-magnetic electromagnetic phenomena like surface plasmon resonances can be tweaked by externally applied low intensity magnetic fields [∼few tens of milli-tesla (0–30 mT)]. Experimental outcomes are explicated by spin-dependent terahertz magnetotransport theory in perforated superlattice metal sheets and, therefore, can stimulate a paragon for spin-based integrated photonic technology.

Numerical investigation on perforated sheet metals under tension loading

Abstract Perforated sheets are used in many areas due to their high specific load, economical production, aesthetic structure, and filtering ability. Their use in industrial machinery and the construction industry can be given as examples of these areas. In this study, the mechanical behaviour of perforated metal sheets under tensile loads has been investigated numerically. The influence of material type, hole geometry, and hole arrangement were examined with finite element analyses. Stainless steel and aluminium materials are used as sheet materials. The hole geometries are circle, ellipse, triangle, square, and hexagon. As a result of the simulations, the aluminium material gave the highest values in terms of carried load capacity and absorbed energy. The sheets with the staggered hole arrangement have higher load and energy values than the sheets with the linear arrangement. The elliptical perforated aluminium sheet provided the highest load value of 28,386 N in the staggered arrangement. In both hole arrangements, the elliptical perforated sheet gave the highest load value, while the triangle perforated sheet gave the lowest load value. The elliptical perforated sheet with linear hole arrangement provided the highest values in terms of specific load (435.57 N/g) and specific energy (0.27 J/g).

Feasibility Study of the SPIF Process Applied to Perforated Sheet Metals

Feasibility Study of the SPIF Process Applied to Perforated Sheet Metals

Nonlinearly tunable extraordinary optical transmission in a hybird metamaterial

Dielectric metamaterials are promising for significantly enhanced optical nonlinearity for their strongly localized Mie-resonant mode. Here, we theoretically and experimentally studied a hybrid metamaterial exhibiting extraordinary optical transmission (EOT) behavior, in which the transmission amplitude and frequency can be modulated. The EOT of the perforated metal sheet with subwavelength aperture is induced with a dielectric cuboid by setting them in a close proximity and exploiting the first-order Mie-resonant mode. The electromagnetic wave is effectively coupled to the subwavelength aperture by properly placing the dielectric cuboid, and the transmission intensity can be enhanced more than 150 times. Meanwhile, we employed the nonlinear effect of the dielectric cuboid to modulate the operation band of the EOT. Hopefully, our work can inspire innovations for the research of light–matter interactions, electromagnetic light switching devices and filter devices.

Predict the Plastic Deformation of Perforated Sheet Metals using Image-based Finite Element Modeling

In this work, numerical prediction of the plastic deformation behaviors of perforated sheet metals, specifically AISI 1018 low carbon steel, C260 Cu-Zn brass, under uniaxial tension was carried out. An image-based mesh generation technique was applied to better represent and discretize the perforated geometry of sheet metal specimens. Digital image correlation measured displacement boundary conditions were also implemented into the finite element modeling. The predicted results of perforated sheet metal under tension as nominal stress-strain curves and localized plastic strain distribution agree well with the experimental observations. Possible error sources and uncertainty of this image-based finite element modeling were also discussed.

"The answer is blowin' in the wind" - case study of a perforated roof screen

A recently-completed building was fitted with a roof screen fabricated from perforated sheet metal panels having "U"-shaped upturned flanges. When wind impinges on the panels, complex tone clusters are generated, leading to complaints from the occupants. The unusual character of the tonal spectrum is reminiscent of a film sound effect intended to simulate a hovering extraterrestrial spacecraft. After some preliminary (but inconclusive) field investigations, it was decided to test samples of the perforated panel in a large commercial wind tunnel where the speed and angle of the airstream could be controlled. Tones generated in the tunnel were found to occur in groups or clusters - these are most pronounced when the airstream's angle of incidence is close to grazing. Gradually increasing airspeed caused the frequency of the tones to "jump" from one cluster to the next higher cluster. The physical principles of the tone-generating mechanism are not fully understood; however, it appears that structural resonances in the panel flanges are excited by air flowing over the perforate. Some form of a positive structural-acoustical feedback loop is involved since a) the frequencies within each tone cluster are quite stable and, b) damping the panel flanges extinguishes the tones.

Elastoplastic Analysis of Perforated Metal Sheets using Transformation Field Analysis and Finite Element Method

This investigation analyzes the cost-benefit ratio of the Transformation Field Analysis to compute the elastoplastic behavior of periodically perforated metal sheets. Evaluation of accuracy and computational cost are analyzed by implementing a finite element approach coupled with the Transformation Field Analysis technique for different meshes and finite element orders. Numerical studies are employed to compare Transformation Field Analysis accuracy with standard Finite Element Analysis for elastoplastic analysis of periodically perforated metal sheets. Additionally, experimental data is employed to validate the Transformation Field Analysis results. The Transformation Field Analysis requires calculating the strain concentration and influencing tensors employing the finite element method. The numerical results show the technique's capabilities and favorable scenarios, besides the influence of domain discretization and finite element order.

Material Modeling of Perforated Sheet Metals with Different Hole Arrangements by Homogenization Method

Material Modeling of Perforated Sheet Metals with Different Hole Arrangements by Homogenization Method

Mechanical properties of glass-reinforced composite/perforated metal sheet hybrids

The mechanical properties of a hybrid structure consisting of a glass–epoxy composite and a perforated metal sheet were evaluated. The composite, hybrid, and resins were produced and their tensile behaviors were measured. Finite-element (FE) modeling was then used to predict the material’s properties, based on the constituent properties, and also to analyze the stress distribution in each material. A new micromechanical model was developed to predict the hybrid’s modulus and strength at different stages of deformation. Both the FE and micromechanical modeling accurately predicted these properties. It was also found that perforating the metal layer of a composite-metal hybrid can increase the specific strength of the material.

Assessment of the influence of façade location and orientation in indoor environment of double-skin building envelopes with perforated metal sheets

Double-skin perforated sheet façades, enclosures consisting of perforated screens, air chambers and glass/wall sheets, are features of modern building design that are winning greater acceptance. A detailed analysis of their suitability across Europe is first performed here. A reference building both with and without the protective double-skin perforated sheet envelope is subjected to a comparative test of solar energy gains with regard to the environment. Additionally, the results of a preliminary survey are presented on the visual perceptions of different patterns of perforated metal sheets. Then the behaviour of these configurations is addressed, through a complete “Energyplus® model” (design builder). A test campaign on a reference perforated screen mounted on a service building of reference was fully monitored over one year, supported by thermographic data recorded for additional validation purposes during the same period. The new parametric energy assessment takes additional variables into account, such as orientation and location of the façade, demonstrating that the real performance for such enclosures greatly depends on them. Accordingly, the influence of different combinations of perforated screens on cooling, heating and lighting loads demonstrates the suitability of a previously optimized configuration in terms of relative energy savings.

A noble method for rapid prototyping of porous micromodels applicable to enhanced oil recovery

In this paper, a noble method for rapid prototyping of porous micromodel in Polydimethylsiloxane (PDMS) with good control over the pore geometry is described. An attempt has been made to demonstrate the making of PDMS micromodels using round hole perforated metal sheet as a master. The geometric shape of the micromodel in PDMS is the negative of the perforated sheet, which gives a section of cylindrical pillars separated by a uniform gap. After peeling off the PDMS from the porous plate, it is sealed with a glass plate to prepare the microfluidic porous channel. This protocol requires only materials that are commercially available, inexpensive and less time consuming. The size of the pores can be adjusted by selecting the perforated sheets having different hole size and thus micromodels with a variety of pore size distribution can be generated using this simple method. The optical visualization experiments were performed to test these fabricated micromodels for their applicability and reliability. Furthermore, Particle Image Velocimetry (PIV) technique is used to get the velocity distribution along the porous section of the micromodel. Identical flow patterns were seen at the different section of the micromodel which again indicated the reliablility of these homogeneous micromodel fabricated by using this noble method. In addition, the velocity profiles are obtained near the throat region of the micromodel at three different flow rates.

High Optical Visibility and Shielding Effectiveness Metal Mesh Film for Microwave Oven Application

A typical microwave oven generates an electromagnetic wave in an ISM band of 2.45 GHz. To prevent this unwanted microwave leakage through its front door, a circular perforated metal sheet is typically used with low shielding effectiveness (<; 27 dB) and with poor visibility (<; 50%) which is usually difficult to check the progress of cooking. In this paper, we investigate sheet resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> ) and optical transparency (OT) for electrical and optical performance of two transparent electrodes (TEs) including metal mesh film (MMF) and indium tin oxide (ITO) and compare those to the currently used perforated copper sheet (PCS) in commercial microwave oven. The measured RS and average OT in visible spectrum of MMF is 0.11 Ω/sq and 68.4%, and its figure of merit (FoM) is 203.8 which is the highest among them. The measured shielding effectiveness of MMF, ITO, and PCS at 2.45 GHz are 31.4, 21.0, and 25.5 dB, respectively. The results indicate that MMF has highest FoM and the best EMC performance among the TEs and PCS, which makes it the most suitable candidate for microwave ovens.