Metallic Panels Research Articles

Analysis of Shielding Performance in Double-Layered Enclosures with Integrated Absorbers

Generally, various technologies, including waveguide below cutoff (WBC), gasket sealing, and bonding, are employed in metallic enclosures to achieve the high electromagnetic shielding performance required for EMP protection and EMC countermeasures in shielding structures or facilities. While the shielding structure or facility is properly constructed and maintained according to design specifications, its electromagnetic shielding performance can remain at the required level, effectively protecting internal electrical and electronic equipment from external electromagnetic interference. However, unintended apertures often occur during the construction or maintenance of shielding facilities, compromising their shielding performance. Therefore, it is crucial to develop technologies that prevent shielding effectiveness degradation caused by both intentional and unintentional apertures. This paper proposes a structure incorporating a composite absorber (made of dielectric and magnetic absorber) within a double metal panel of enclosure featuring an aperture, aimed at maintaining and improving the facility’s shielding performance. The effectiveness of the proposed structure was validated through numerical simulation.

A-115 Iron assay improvement: The need for thiourea addition in Ferene/Ferrozine reagent cartridge

Abstract Background Iron assay is often ordered along with ferritin, transferrin, and iron binding capacity in patients suspected of having iron deficiency anemia or iron overload. A ferene/Ferrozine chromogen-based iron assay is more common in College of American Pathology accredited laboratories across U.S. Recently, a product recall/field safety notice was issued by a major manufacturer for several lots of ferene based iron reagent due to unacceptable positive bias in patient iron results. However, the reason(s) underlying this positive bias was not provided. In this report, we investigated the possible causes for the recall of specific lots of iron assay reagents. Methods The performance of 2 lots of recalled iron test kits was compared against 2 good lots (Sentinel Diagnostics) on the Alinity c analyzer utilizing approved calibrator lots, quality control (QC) materials (Bio-Rad Laboratories), and excess/leftover de-identified patient samples. Spectral scan (in the visible wavelength) of good and recalled lots of reagents, R1 and R2 was performed on the Tecan microplate reader. Trace elements in R1 and R2 reagents were estimated with Quantitative Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Spiking experiments in calibrator, discarded patient samples, and reagents were undertaken to further elucidate the cause and prevention of positive bias seen with recalled reagent lots. Graphs and statistical analysis were generated using Graphpad prism 10.1. Results Iron levels in QC materials and de-identified patient samples (n=42) tested with 2 recalled lot of reagents on Alinity c analyzer showed a positive bias of 15-36% compared to unimpacted lots of reagents. Calibrator and blank absorbance of recalled lots was much higher than the unimpacted lots. Percentage change in the basal absorbance of recalled vs unimpacted R2 reagent measured from 500 to 600 nm in 25 nm increments and corrected to 700 nm ranged from 150 to 250%. No such changes were noted with both R1 reagents. Interestingly, ICP-MS heavy metal panel analysis revealed that R2 reagent of the recalled lots had unanticipated presence of Cu (∼22 υg/dL) and lead (7.5 υg/L), which was not present in R1 reagents. Increased concentrations of Cu spiking (100, 200, and 400 υγ/dL) in R2 reagent from recalled lots discernibly increased the Cal Factor values as well as patient iron results relative to unspiked reagent. Further, the presence of Cu over time deteriorated the accuracy of R2 reagent reflecting on very high rise in Cal Factor and patient iron values. Interestingly, TU addition to R2 reagent from unimpacted lot prevented the Cu-induced spurious rise in Cal Factor and iron measurements in the patient samples. Further, TU exhibited sustained preventive effect on Cu-induced iron measurement changes over time. Conclusions Based on our investigation, we conclude that copper contamination of R2 reagent is the possible cause for the positive bias in the recalled iron assay reagent lots. We recommend the addition of TU to Ferene containing R2 reagent pack as a simple and effective step to prevent Cu-induced false elevation in iron values.

In-process part tracking and shape measurement using vision-based motion capture for automated English wheeling

An English wheel is an exceedingly adaptable instrument in traditional metalworking. It is a manual manufacturing technique, enabling skilled craftsmen and blacksmiths to shape complex compound curves in sheet metal panels. Accurate measurements and precise adjustments are essential when operating an English wheel to ensure that the metal is shaped with the desired curvature. An automated method to form English wheeled panels through robot forming has recently been proposed. For such a method to be successful, accurate tracking of sheet information including positions, orientations, and deformation is important for error compensation and the design of the subsequent tool paths. In this study, a Vicon motion capture system is employed to monitor the position and shape of the sheet metal during the English wheeling process. The initial experimental results demonstrate the potential of such an in-process metrology system, along with possible avenues for future work.

Assessment of cantilevered curtain wall system supported by tension rods for an enclosed circular building

Curtain wall systems have undergone significant advancements to meet the evolving architectural requirements and achieve aesthetic appeal and functionality in buildings worldwide. These non-structural enclosures, typically constructed with lightweight materials like glass or metal panels, contribute to the visual appeal of high-rise structures while providing numerous benefits, such as ample natural light and unobstructed views. The current paper focuses on analyzing and designing a cantilevered curtain wall system supported by tension rods for the auditorium façade at a simulation centre. The curtain wall surrounds the entire primary structure of the building, which has a circular layout. The study uses numerical modeling with the Robot software to analyze stresses and deflections in the glass, tension rods, mullions, and transoms while considering a wind load of 1.6 kPa. According to the findings, tempered laminated glass that is 19.52 mm thick satisfies the Ultimate Limit States (ULS) and Serviceability Limit States (SLS). Under the limit states, the Technal system (FM169) reinforced with steel tubes can transfer the design loads. The steel framing system that supports the tension rods and transfers the load of the curtain wall to the main structure is likewise considered safe. The structural integrity of the curtain wall is ensured by the prescribed requirements for the connections, which include a 5 mm fillet weld with a throat thickness of 3.5 mm, 20 mm diameter tension rod (Kin long system), and 8 mm thick MS plates with channel brackets. This research expands the practical application of cantilevered curtain wall systems of buildings with enclosed circular layouts.

A Comparative Blast Mitigation Performance Evaluation of Metallic Sandwich Panels with Honeycomb, Corrugated, Auxetic, and Foam Cores

Due to the high energy absorption capability and excellent bending strength of the sandwich panels, they are mostly preferred as protective structures against explosive blast attacks. The evaluation of their blast-mitigation characteristics through experiments is highly dangerous, costly, time-consuming, and polluting for the environment. Therefore, in this presented work, a series of numerical analyses were performed to evaluate the blast mitigation of the outstanding sandwich panels with honeycomb, corrugated, auxetic, and foam cores. The masses of sandwich panels were kept constant, and their areal densities were maintained constant throughout the study to effectively compare their performance under identical air blast loading conditions. To apply the air blast loads to the designed sandwiches, 1–3[Formula: see text]kg of spherical-shaped trinitrotoluene charges were used for a 100[Formula: see text]mm stand-off distance. The sandwiches are made of high-strength AL-6XN steel and crushable aluminum foam. The rate-dependent Johnson–Cook constitutive model of plasticity and the crushable foam model with volumetric hardening were used for the evaluation of sandwich panels’ plastic deformations. The findings of the work depicted that the honeycomb core is more efficient than the other core structures of the same masses because the sandwich panels with honeycomb core provide smaller back skin deflections, globalized core crushing, and higher core energy absorption than the other sandwich panels for extreme conditions of air blast loading.

Performance investigation of metal foam coupled to phase change material as coolant of photovoltaic concentrator systems: Optimization and electrical efficiency analysis

This research investigates the integration of graphitic metal foam with paraffin RT35HC to manage and reduce the temperature of PV cells, focusing on the rigorous examination of the synergistic effects of metal foam porosity and panel inclination on thermal management. A 2D numerical model was developed using ANSYS Fluent 14.0, where User-Defined Functions (UDFs) were employed to incorporate the Darcy-Brinkman-Forchheimer and Carman-Kozeny equations, accurately accounting for the effects of metal foam porosity on thermal conductivity and fluid flow resistance. Various foam porosities (ε = 0.80, 0.85, 0.90, 0.95, 1) were explored on both vertical and tilted panels across a spectrum of inclination angles (β= 0°, 30°, 45°, 75°, 90°). Results highlight critical parameters including PCM melting fraction, cell temperature evolution, and the resultant impact on solar cell electrical efficiency, both with and without metal foam. The integration of graphitic foam with RT35HC contributed to superior heat transfer and a marked reduction in cell temperature of the employed PV system by improving thermal conductivity and heat dissipation, particularly at slight inclination angles (β =0° to 30°), revealing a noteworthy enhancement in electrical efficiency ranging from 1.3 % to 3 %, respectively. Conversely, the absence of graphitic foam at steeper angles (β =45° to 90°) surprisingly strengthens the solar panel’s electrical performance. These findings provide valuable insights into the effects of metal foam integration at varying inclination angles, offering a pathway for the development of more efficient and reliable solar energy systems.

Gradients of properties increase the morphing and stiffening performance of bioinspired synthetic fin rays

State-of-the-art morphing materials are either very compliant to achieve large shape changes (flexible metamaterials, compliant mechanisms, hydrogels), or very stiff but with infinitesimal changes in shape that require large actuation forces (metallic or composite panels with piezoelectric actuation). Morphing efficiency and structural stiffness are therefore mutually exclusive properties in current engineering morphing materials, which limits the range of their applicability. Interestingly, natural fish fins do not contain muscles, yet they can morph to large amplitudes with minimal muscular actuation forces from the base while producing large hydrodynamic forces without collapsing. This sophisticated mechanical response has already inspired several synthetic fin rays with various applications. However, most ‘synthetic’ fin rays have only considered uniform properties and structures along the rays while in natural fin rays, gradients of properties are prominent. In this study, we designed, modeled, fabricated and tested synthetic fin rays with bioinspired gradients of properties. The rays were composed of two hemitrichs made of a stiff polymer, joined by a much softer core region made of elastomeric ligaments. Using combinations of experiments and nonlinear mechanical models, we found that gradients in both the core region and hemitrichs can increase the morphing and stiffening response of individual rays. Introducing a positive gradient of ligament density in the core region (the density of ligament increases towards the tip of the ray) decreased the actuation force required for morphing and increased overall flexural stiffness. Introducing a gradient of property in the hemitrichs, by tapering them, produced morphing deformations that were distributed over long distances along the length of the ray. These new insights on the interplay between material architecture and properties in nonlinear regimes of deformation can improve the designs of morphing structures that combine high morphing efficiency and high stiffness from external forces, with potential applications in aerospace or robotics.

Exploring the enablers for building resilience in solar photovoltaic Energy supply chains

A solar photovoltaic energy supply chain (SPvESC) is a global network with several linkages, including mineral and metal mining, material processing, and module and panel manufacturing. Due to the wide range of uncertainties and the unfavorable environmental effects associated with current linear business models, this global network is vulnerable to disruptions. Strengthening the resilience of SPvESCs is crucial for addressing any disturbances. This requires identifying the key enablers of resilience in SPvESCs, an area that has been understudied in the existing literature. An enabler is an aspect that facilitates the achievement of a goal by another aspect. This research contributes to the existing literature by systematically investigating the enablers for SPvESCs to achieve resilience. Thus, the objective of this analysis is to identify enablers that have the potential to enhance the resilience of SPvESCs in Türkiye. This was done by applying the Nominal Group Technique (NGT) in conjunction with a review of the current literature. Neutrosophic (N)-DEMATEL was then utilized to determine the relationships between the identified enablers. Finally, the results were validated using N-DELPHI. The results revealed that sensing and seizing new business models, adaptability to changes in novel energy generation and information technologies, and business contingency plans for natural and man-made disasters were the most influential enablers. The findings provide implications for practitioners, policymakers, and researchers to help ensure improved resilience in SPvESCs.

Efficient design of composite honeycomb sandwich panels under blast loading

Hybrid composite honeycomb sandwich structures (HCHSS) were employed due to high specific strength and stiffness and higher impact resistance property required for the aerospace and defence fields. The numerical modelling of the efficient HCHSS was developed for the core, front and back face plate using the C3D8R elements to determine the realistic failure behaviour for the honeycomb sandwich structure. The ConWep blast simulation loading was applied for the HCHSS. Advanced composite materials were used for the blast analysis of the HCHSS (carbon/epoxy, graphite/epoxy, woven basalt fibres/polypropylene and woven Kevlar fibres/polypropylene). The damage initiation and damage propagation based progressive damage modelling was developed and implemented in the VUMAT code for composite materials to determine the actual failure behaviour of the HCHSS. The face sheets used in this model were of a stainless-steel alloy AL-6XN. The sandwich structure was subjected to blast loads of 1, 2 and 3 kg of TNT and their performance was compared w.r.t both front and back-face deflection. The effectiveness of sandwich panels was further examined by altering the thickness of the core. Fibre-metal laminates (FML) were used in place of the steel face sheets in the panel in order to minimise its mass, and a thorough analysis of the panel’s mass in relation to its peak deflection was carried out. Upon analysing the results, it was noted that the panel with the basalt fibre reinforced polymer (BFRP) core gave the best results compared to other composite materials. For a blast load of 3 kg TNT, the peak back face deflection (PBFD) of HCHSS with a BFRP core decreased by 10.64%, 7.61% and 4.75%, respectively, compared to panels with CFRP, GFRP, and KFRP cores. The peak deflection of the panel decreased as the BFRP core thickness increased. The energy absorption capacity of the panel also increased with increasing thickness. Additionally, it was found that panels with BFRP cores and KFRP-steel laminate face sheets provided the optimum balance of strong blast resistant performance and light weight. Compared to the metallic (steel) sandwich panel, the mass of the sandwich panel with KFRP-steel laminate face sheets and BFRP core was reduced by 33%, but at the same time, its PBFD increased by almost 50%.

Evaluation of metal ions and DNA recovery from the surface of fired and unfired brass ammunition to improve STR profiling.

Interest in recovering DNA from the surface of ammunition evidence for genotyping has increased over the past few years. Numerous studies have examined a variety of methods to maximize DNA recovery from these types of challenging samples, but successful DNA profiling has been inconsistent. Low amounts of DNA and PCR inhibition due to metal ions have been suggested as the leading causes of poor results; however, no study quantitatively examined the presence of metal ions at various stages of the DNA analysis workflow from DNA collection through to amplification. In this study, the effectiveness of six different DNA collection and purification methods commonly used by forensic laboratories to process brass ammunition for DNA evidence was investigated. The amount of copper, zinc, and other metals co-recovered from fired and unfired brass casings during DNA collection (using numerous soaking, swabbing, and direct PCR protocols) was quantified via Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES). This same panel of metals was subsequently quantified after DNA lysis and purification steps. Results demonstrated that low amounts of DNA, DNA damage, and degradation are more detrimental to STR typing results than PCR inhibition, as metal ions were successfully removed by all DNA purification methods tested. Furthermore, the use of metal ion chelators increased the amount of DNA recovered and number of reportable STR alleles. This research informs the forensic community on the most effective way to collect and process trace amounts of biological material from brass ammunition and similar evidence.

Factors to Consider in Developing Conceptual Scopes of Repair for Common Low-Slope Roofing Assemblies

Forensic engineers are commonly asked to develop conceptual scopes of repair as part of their work. Many factors impact these recommendations, including building codes, construction feasibility, manufacturer assessment, and installation requirements. In addition, the conditions present on and within the existing roof surfaces can limit the repairability of a commercial roof assembly such that removal and replacement of the entire roof section is the appropriate or only feasible repair option. This paper will focus on common limitations to be considered when developing a conceptual scope of repair for common commercial roof systems, including single-ply membranes, built-up roofing, metal panel roofing, spray polyurethane foam roofing, and the application/maintenance of roof coatings. It will also discuss an assessment methodology that can assist in developing a broader understanding of the condition of the roof surfaces.

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.

Mechanical and energy absorption properties of multilayered ultra-light sandwich panels produced by 3D-printing and electroforming

This investigation aims to assess the mechanical and energy absorption properties of the light sandwich panel portions made of open-cell polymer and metal/polymer foam cores. These multi-layered sandwich panels were produced by additive manufacturing of polymeric resin and electrodeposition of three layers of metals, Ni/Ni−Cu/Ni, with 4,5, and 6 pores per inch (PPI). The yield strength, energy absorption density, complementary energy, and specific energy absorption (SEA)were measured during uniaxial compression deformation. The results indicate that compared with pure Ni and Cu sandwich panel portions with the same thickness, the abovementioned properties of the sandwich panels had a noteworthy improvement. Mechanical and energy absorption properties were improved by increasing the PPI and the presence of metallic layers. In a sandwich panel with 6 PPI, the yield strength (energy absorption density)wasimproved from 0.12 MPa (0.12 MJ/m3) for the polymeric sandwich panel to 1.83 MPa (0.67 MJ/m3)for the metallic sandwich panel. Investigations on normalized energies of these structures show a predictable behavior for these sandwich panels during plastic deformations. The results show that the multi metallic layers improved the mechanical behavior of these novel sandwich panels. Noticeable enhancement of the calculated properties of these advanced materials guarantees their unique application in variable industries.

Construction hoisted in buildings of resistant metal panels. Some constructive aspects of the Reverstop system

Construction hoisted in buildings of resistant metal panels. Some constructive aspects of the Reverstop system

A High-Gain Pattern and Beamwidth Reconfigurable Dielectric Resonator Antenna based on Parasitic Metal Panels

A High-Gain Pattern and Beamwidth Reconfigurable Dielectric Resonator Antenna based on Parasitic Metal Panels

Dynamic response of square sandwich panels with stagger-layered honeycomb cores under intensive near-field air blast loading

Metallic honeycomb sandwich panels have been widely used in energy dissipation due to large plastic deformation under impact/blast loading. In this paper, the dynamic response of a honeycomb sandwich panel with stagger-layered core under intensive near-field air blast loading is investigated. Comparative experiments are conducted for stagger-layered and typical honeycomb sandwich panels with the same geometrical size and mass. Numerical simulation has been undertaken based on the experiments. Numerical results coincide well with experimental results on the deformation/failure modes and center-point deflection of back face sheet. The influence of layer number as well as the geometrical parameters on the energy absorption ability of sandwich panels is clarified. Results show that stagger-layer arrangement of honeycomb core greatly improves energy dissipation capability of sandwich panels compared to typical one with the same mass. The increase of layer number and cell size benefits this effect. These findings indicates that core stagger-layer arrangement is a well choice to improve energy dissipation ability of sandwich panels under air blast loading, especially for highly intensive near-field blast loading.

Automated bondline thickness quantification in adhesively joined composites and metals using ultrasound

AbstractThe use of adhesively bonded joints between composite panels, metal panels, or between composites and metals are used in the aerospace and automotive industries to avoid stress concentrations due to fasteners while reducing weight. Quantifying the bond thickness allows for confidence that loading is being properly transferred. This study presents a methodology to measure bondline thickness using the data obtained from an immersion quality ultrasound scan using an out‐of‐tank, field‐portable, utlrasonic testing (UT) scanner. Eighteen bonded coupons were fabricated using a paste‐type adhesive filling a range of gaps between substrates of 0.254 and 1.27 mm. Three adhesively bonded coupon types were investigated: carbon fiber laminates, fiber glass laminates, and aluminum plates. A semiautomated algorithm is presented to quantify bondline thickness from the ultrasound data for each coupon type, generating a spatially varying 3D point cloud of adhesive thickness. Bondline measurements obtained using ultrasound are then validated over two orthogonal planes against measurements taken from x‐ray computed tomography reconstructions. Results indicate a typical accuracy of 0.081 mm for bondline thickness quantification for all samples studied, with the results from the inspection of the composite coupons yielding an error of 0.078 mm, whereas the accuracy when scanning the aluminum coupons yielded an error of 0.086 mm.Highlights Field‐portable, inspection station is presented for full waveform ultrasonics. Mathematical procedure to characterize adhesive bondline thickness. Results are presented for a variety of material systems and adhesive thicknesses. Results are validated against x‐ray computed tomography with a typical accuracy of 0.081 mm.

Design guidelines for the morphing of stiff lattice materials

Materials and structures with shape morphing capabilities are attractive in aerospace, maritime vehicles and robotics: such systems offer lighter weight, better distributed stresses, simpler kinematics, smaller numbers of actuators and higher reliability. Current morphing materials are either very compliant to achieve large shape changes (metamaterials, compliant mechanisms, hydrogels), or very stiff but with infinitesimal shape changes that require large actuation forces (metallic or composite sandwich panels with piezoelectric actuation). Morphing efficiency and structural stiffness are therefore mutually exclusive properties in current engineering morphing materials, which limit the range of their application. Here we propose a design for a stiff morphing beam made of “meta-elements” with unusual combinations of elastic properties, and which can be actuated from a simple push/pull at the base. To capture the performance of the beam we propose and use three metrics: The “morphing amplitude”, the “morphing compliance” and “structural stiffness”. We develop nonlinear finite elements to explore a wide range of designs, and to show some inevitable tradeoffs of stiffness and morphing. To aid the design of the structure we propose ternary diagrams to select optimum combinations of properties for the meta-elements. Finally, we fabricated and tested three prototypes of stiff morphing beams to validate the approach.

ELIMINATION OF THE DEFECTIVE LAYER AND STRESS CONCENTRATORS DURING MICROMACHINING OF HOLES IN THIN SHEET BLANKS OF METAL CELLULAR PANELS

Thin-sheet blanks made of aluminum (in particular, AMg2-N), titanium (VT-15, VT-19) or stainless (12X17) alloys are widely used in the production of honeycomb panels in the aviation and space industries. Foil (thickness 0.025-0.055 mm) is used for the production of fillers for cellular sandwich panels; it is pre-perforated with holes of 0.05-0.18 mm and laid out in a corrugated box with adhesive strips. The possibility of making holes by the laser jet method is considered, as it precedes the occurrence of mechanical damage and thermal defects of the surface adjacent to the treatment zone. It is shown that the Water Jet Guided Laser (WJGL) is an effective and efficient method of obtaining profile holes in the fillers of cellular panels and in the panels themselves, which is characterized by high productivity and allows obtaining holes without thermal and mechanical defects. The method can be used both for foil fillers and for metal panels made of stainless steel up to 1.5 mm thick.

Об одном из подходов к прогнозированию и повышению шумопоглощения в кабинах транспортно-технологических машин

Noise is one of the main harmful production factors in the mining industry. The results of a hygienic assessment of working conditions indicate that exceeding the maximum permissible noise levels in 50 % of cases is recorded at the workplaces of drivers of the transport and technological machines. One of the efficient measures to reduce medium- and high-frequency noise in the cabins of transport and technological machines is the use of noise-absorbing upholsteries mounted on their metal panels. The article presents a computational and experimental procedure based on determining the reverberation coefficient of sound absorption of flat-sheet pressed samples of materials manufactured using the production technology of serial molded upholsteries. The material samples contained a base layer of open-cell polyurethane foam, a reinforcing layer of fiberglass, a thermally activated adhesive layer, a front layer of needle-punched fabric, and a back layer of non-woven fabric. The values were determined related to the sound absorption coefficient of flat-sheet pressed samples of materials manufactured using representative technology. The measurements were carried out with different sizes of air gaps relative to the reflective surface. As an example, the results of calculating the equivalent sound absorption area of the roof lining of a truck cab are considered. The obtained values of the equivalent sound absorption area for the original design option are below the target values for this part by up to 31 %. The original version was modified by changing the thickness of the molding of the blank and its location relative to the metal panel of the cabin without changing the material and design. As follows from the calculation results, the values of the equivalent sound absorption area of the roof lining in the modified version ensure that the target requirements are met.