Thin Metallic Structures Research Articles

Design of high quantum efficiency SPAD single-photon detector based on metasurface

This work discusses several metasurface structure types, their manufacturing processes, and the design and simulation of nanopyramid arrays, square slot arrays, and funnel arrays to improve absorption. In particular, a silicon-based continuous thin gold film-covered deep grooved thin metal structure was constructed and examined. It surpasses the silicon materials’ absorption thresholds, considerably expanding the NIR’s absorption range to 2000 nanometers. More information is provided regarding the impact of trench depth on cavity pattern and near-infrared absorption. Its preparation process is detailed, and its compatibility with SPAD single-photon detectors is confirmed. This information is likely to encourage the use of SPAD in domains such as near-infrared optical communication and other low-light detecting technologies.

A Self-Assembled 3D-Shaped Microstrip Microwave Device Inspired by the Origami Structure

An innovative design method inspired by origami is proposed for the 3D-shaped microstrip microwave device in this paper. A self-assembled microstrip low-pass filter inspired by the origami structure is designed, fabricated, and measured. The experimental results of the prepared prototype demonstrate the validity of the origami-based design method for stereoscopic microstrip microwave devices. This work provides a simple method to fabricate thin stereoscopic metal structures of microstrip microwave devices.

Modeling and design of monolithically coated thermal components

Thermal management is key to the success of modern electronics as it primarily eliminates hotspots and reduces active and passive device temperature fluctuations. As long as the thermal and electrical designs constrain one another, simultaneous electro-thermal co-design will be required. The electro-thermal co-design will need to use trial-and-error approaches if the thermal design framework and rigorous understanding of the different operation modes is absent. Here, we provide a rigorous analysis of heat spreading within monolithically integrated thin metallic structures to develop design guidelines for efficient implementation in modern circuitry. We begin by outlining the different modes of operation for thin integrated heat spreaders, propose representative figures of merit, and develop an analytical/numerical model that predicts thermal operation at steady state under a wide range of configurations. We validate the accuracy of our model by comparing with Ansys Icepak computational fluid dynamics (CFD) simulations as well as experiments. After validating our model, we extend our analysis to encompass heat routers and heat shields to investigate their implementation and design strategies in two representative case studies. Our work galvanizes the co-design and implementation of innovative thermal devices with electronics to enable unprecedented power density and reliability.

Adjustable Cone Meter Adapts Automatically to Wet-Gas Conditions

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 207505, “Using an Adjustable Cone Meter To Measure Wet Gas,” by Sakethraman Mahalingam, SPE, Saudi Aramco; Gavin Munro, SPE, GM Flow Measurement; and Muhammad Arsalan, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. _ A traditional fixed-size Venturi meter has a turndown of approximately 8:1 under dry-gas conditions that may drop to as low as 3:1 under wet-gas flow. When the well conditions change, a replacement of the original Venturi meter with one of a different size is needed. In the complete paper, the authors present the design, development, and testing of an adjustable cone meter that has the ability to adapt itself to flow conditions automatically and provide a turndown of as much as a 54:1 under dry-gas conditions and as much as 20:1 under wet-gas conditions. Adjustable Cone Meter Design The adjustable cone meter is a variation on a traditional differential pressure cone meter. A moveable sleeve is placed within the meter, and its position is moved using a rack-and-pinion arrangement. When the flow rate is high (Fig. 1a), the sleeve is downstream of the cone and the meter operates like a normal cone meter. This means that the differential pressure at the cone (P1–P2) is sufficiently high and within the measurable range of the meter. When the flow rate drops below a preset value, however, the differential pressure (P1–P2) drops below the measurable range of the meter. While a conventional cone meter would be unable to measure such flow rates, the adjustable cone meter is able to achieve accurate measurements because the meter detects that the differential pressure is below the measurable range and moves the sleeve automatically so that it covers the cone (Fig. 1b). This reduces the internal diameter of the flowline around the cone and causes the differential pressure to move into the measurable range. The meter then uses the differential pressure to again produce accurate flow measurements. In addition, the meter has a second differential pressure sensor downstream of the cone. This is used to measure the liquid fraction of the wet gas. Meter Design Exhaustive finite-element analysis (FEA) was conducted to determine the operating stresses within the meter body and its pressure-containing components during operation. The sliding sleeve can maintain full line pressure and features double-pressure seals at either end, safely containing fluids inside the flowline. The primary risk is the deformation and failure of the sliding sleeve because it is a thin metal structure. However, FEA established the minimum working pressure of at least 1,200 psi for the sleeve, gearbox, and meter body, using industry-standard safety factors. Cone meter calculations are provided in the complete paper.

Intracellular Cargo Delivery Induced by Irradiating Polymer Substrates with Nanosecond-Pulsed Lasers.

There is a great need in the biomedical field to efficiently, and cost-effectively, deliver membrane-impermeable molecules into the cellular cytoplasm. However, the cell membrane is a selectively permeable barrier, and large molecules often cannot pass through the phospholipid bilayer. We show that nanosecond laser-activated polymer surfaces of commercial polyvinyl tape and black polystyrene Petri dishes can transiently permeabilize cells for high-throughput, diverse cargo delivery of sizes of up to 150 kDa. The polymer surfaces are biocompatible and support normal cell growth of adherent cells. We determine the optimal irradiation conditions for poration, influx of fluorescent molecules into the cell, and post-treatment viability of the cells. The simple and low-cost substrates we use have no thin-metal structures, do not require cleanroom fabrication, and provide spatial selectivity and scalability for biomedical applications.

Optical biosensing with electromagnetic nanostructures

Abstract The recent development in the field of optical biosensors based on plasmonic metamaterials, all-dielectric metamaterials and two-dimensional (2D) materials inclusive of van der Waals heterostructure have been reviewed in this article. Plasmonic metamaterials are divided based on their geometrical design, such as thin metallic film structures, an array of periodic structures, and single nanoparticle that are governed by the physical phenomenon of plasmon resonance. On the contrary, all-dielectric metamaterials based sensors are governed by the Mie scattering. Two-dimensional material exhibits high surface area to volume ratios, which makes them a strong candidates for realizing high sensitivity. This review encompasses all the latest developments over the last decade and forecasts the roadmap.

Design and optimization of crashworthy components based on lattice structure configuration

Designing crashworthy components requires a special structural configuration that provides effective crushing deformation to absorb crash impact energy. Recent developments in crash impact energy absorption for crashworthy components include thin wall structures, honeycomb structures, and metallic foam sandwich structures. The honeycomb and metallic foam structures appear to have high specific energy absorption capability. However, both structural configurations have a shortcoming, i.e. honeycomb structures only have the unidirectional capability, while the metallic foam structures have highly irregular (random) three-dimensional cell configuration.The advanced development of additive manufacturing has paved the way for the developments of complicated geometry that will support the development of crashworthy components in the form of lattice structures. The lattice structures provide both three-dimensional and regular structural configurations that are able to absorb crash impact energy efficiently. Therefore, lattice structures have excellent potential to be used for energy management of crash impact structures. Eleven types of lattice configurations were examined to determine the highest specific energy absorption capability, i.e. kagome, tetrahedron, pyramid, cube, truncated-pyramid, octahedron, rhombicuboctahedron, rhombic dodecahedron, open-cell, and octet lattice structures. Numerical analysis and design optimization were performed on a single cell unit of each lattice configuration. It was found that the optimum lattice configuration for crashworthy components was the octet lattice structure.Further topology optimization of the octet lattice configuration resulted in an optimum solution of the octet structure in the form of a twisted octet lattice structure. The twisted lattice structure with 20% relative density was able to generate the highest specific energy absorption. A case study on an aircraft subfloor surface structures showed that the twisted lattice structure was able to absorb aircraft grounding impact energy efficiently. General buckling failure in the twisted lattice structure can be avoided by using a tapered configuration. This tapered lattice structure has a high potential to provide specific energy absorption of up to 127 kJ/kg. These results show the potential applicability of the lattice structure for aircraft crashworthy components.

Impact of damping on decay time of free oscillations in metal structures

The problem of increase of durability of the bearing thin walled metal structures of hoisting - and - transport machines maybe solved by means of structural damping which allows to increase the logarithmic decrement of the damped oscillations. In the work there are given the results of modelling and experimental check of the advantages of usage low-modulus foam materials as fillers at a structural damping of thin walled elements of metal structures. With the help of computational package SolidWorks there was conducted a numerical study to define amplitude-frequency characteristic of laboratory machine and then there were run the tests of model structure with building vibrorecord. As a result if research there was revealed a significant increase of the logarithmic decrement and reduction of the time of decay of natural oscillation of the foamed structure. Consequently, there are shown the advantages of the further researches to use energy-intensive foam materials to dampen the elements of the structures of handling machinery.

Influence of laser weld shape on mechanical and fatigue behaviour of single lap laser welded joints

Traditional manufacturing processes, like arc welding and resistance spot welding, are still the main welding processes to join structural components used across the on/off-road vehicle industry. Due to the abundance of data, experiences and insights over the decades of usage, lot of fatigue design data has been generated for different joint geometries produced using these methods. The laser welding process has excellent capabilities to join thin sheet metal structures with minimum heat input resulting into lower deformation and improved productivity that offers significant benefit as compared to the arc and resistance welding processes. However, due to the agility of designing joint configurations and limited availability of understanding regarding the fatigue behaviour of laser welded joints, the need arises for the fatigue design data. Most of the research presents the use of straight linear shape laser welds and limited knowledge exist regarding the influence of shape of laser welds on mechanical and fatigue performance of the laser welded joints. The laser welded joints produce small notch like radius at the root of laser weld which could act as a stress raiser causing early crack initiation. For this work, C-shape laser weld has been selected as the geometric shape in comparison to the straight linear shape of laser weld produced on a series of single lap joints. Detailed fatigue experimental investigation has been carried out for linear and C-shape laser welded joints tested in 3 different orientations with respect to the applied cyclic load and several different R-ratio's and the results are compared. The metallurgical studies have been carried out to understand the failure mode and micro-hardness variations across the weld and heat affected zone. Further, the residual stress profiles have been compared for the C-shape laser weld with the linear welds using detailed X - Ray Diffraction based residual stress measurement.

Long distance distortions in the graphene near the edge of planar metal contacts

The properties of the planar junction between graphene layer and thin film metal structures are important for formation of the electronic devices integrating the structures of the two-dimensional materials. However, the properties of the graphene-metal contacts are still weakly controlled in the large area device fabrication. In this report we demonstrated an approach acceptable to characterize the long distance distortion area produced by the metal contact edges in the graphene monolayer. The systematic analysis of the Raman maps of the graphene is performed aiming to describe the changes in the graphene monolayer produced by the technology dependent parameters in the planar structures used for the measurements by the circular transmission line method. It was proved that Au contacts produce the compressive strain in the graphene layer in the distances up to about 2–4 μm from the contact edges. The transition between the n- and p-type of the doping is combined with the compression strain in the long distance graphene distortion area close to the Ni-contact edges. An equivalent electrical circuit is proposed for description of the graphene distortion area near the contact edges.

Numerical analysis of temperature distribution during laser deep welding of duplex stainless steel using a two-beam method

The present investigation focused on the numerical determination and subsequent optimisation of the temperature distribution during laser welding of thin metal structures made of duplex stainless steel (X2CrNiMoN22-5-3). This work describes a theoretical way to deliberately reduced the process-related high cooling rates using a numerically modelled two-beam-method. At first, the welding parameter-dependent temperature fields were analysed and validated without post-heating by modelling a flow body whose temperature field has reached the stationary state. Based on state-of-the-art-literature, the determination of temperature-dependent fluid and thermodynamic material data has been carried out. The keyhole, which is the central element of energy input during laser deep welding, was modelled as a solid wall. In addition, the most important influences of the complex molten pool flow, such as Marangoni convection, were included. Experimental welding tests and the preparation of metallographic microsections were used to validate the simulations without reheating. The second laser beam was numerically modelled using different intensity distributions. By means of this procedure, the simulations of three different reheating strategies were carried out.

Challenges in the Automation of Eddy Current Evaluation for Aerospace‐Spacecraft Propellant Tanks

AbstractAn automated system is designed for Eddy current evaluation of spacecraft components with a proven multi‐axis industrial robot interfaced with dynamic electromechanical distance compensation device (EMDC), automated probe exchange, array eddy current probe, precision component fixtures and turntables, eddy current equipments, centralized control system to control robot and eddy current system with seamless handshake capability. Accuracy of the probe guidance system for the entire test period is ensured by the repeatable probe positioning within ±0.05mm by the robot and a minimal lift off error of ± 50μ, achieved by deploying an automated device with a high precision component turntable with positioning accuracy of £0.005°. The component is aligned initially by LASER and fine alignment is established by Infrared based touch‐tool.Automation of eddy current based evaluation technique has made the system state of the art with high probability of defect detection capability at a lesser evaluation time. Also the system has enhanced process confidence level due to the high positional accuracy of the system in comparison with manual methods, with defect detection capabilities up to depth of 0.12mm on a shell of 0.8 mm thickness. The challenges in automation of the system include intricacies due to component's thickness and also due to the complex hemispherical profile of the component. Fixtures were designed to provide enough support for the fragile components with soft pads at the contact area, and alignment of component in turntable to avoid surface run‐out errors, synchronization between turntable and the robot scanning speed, precision maintenance of lift‐off distance between eddy current probe and component surface, array eddy current probe design with multiple elements ensuring defect detection in any orientation are some of the challenges overcome in the automation of eddy current evaluation technique.The challenges in designing an automated eddy current system for evaluation of propellant tanks were systematically overcome with automation to get better defect characterization capability with reduced test time aiding in design optimization of thin walled metallic structures like propellant tanks.

Bending Strain and Bending Fatigue Lifetime of Flexible Metal Electrodes on Polymer Substrates.

As the technology of flexible electronics has remarkably advanced, the long-term reliability of flexible devices has attracted much attention, as it is an important factor for such devices in reaching real commercial viability. To guarantee the bending fatigue lifetime, the exact evaluation of bending strain and the change in electrical resistance is required. In this study, we investigated the bending strains of Cu thin films on flexible polyimide substrates with different thicknesses using monolayer and bilayer bending models and monitored the electrical resistance of the metal electrode during a bending fatigue test. For a thin metal electrode, the bending strain and fatigue lifetime were similar regardless of substrate thickness, but for a thick metal film, the fatigue lifetime was changed by different bending strains in the metal electrode according to substrate thickness. To obtain the exact bending strain distribution, we conducted a finite-element simulation and compared the bending strains of thin and thick metal structures. For thick metal electrodes, the real bending strain obtained from a bilayer model or simulation showed values much different from those from a simple monolayer model. This study can provide useful guidelines for developing highly reliable flexible electronics.

An Equivalent-Effect Phenomenon in Eddy Current Non-Destructive Testing of Thin Structures

The inductance/impedance due to thin metallic structures in non-destructive testing (NDT) is difficult to evaluate. In particular, in Finite Element Method (FEM) eddy current simulation, an extremely fine mesh is required to accurately simulate skin effects especially at high frequencies, and this could cause an extremely large total mesh for the whole problem, i.e. including, for example, other surrounding structures and excitation sources like coils. Consequently, intensive computation requirements are needed. In this paper, an equivalent-effect phenomenon is found, which has revealed that alternative structures can produce the same effect on the sensor response, i.e. mutual impedance/inductance of coupled coils if a relationship (reciprocal relationship) between the electrical conductivity and the thickness of the structure is observed. By using this relationship, the mutual inductance/impedance can be calculated from the equivalent structures with much fewer mesh elements, which can significantly save the computation time. In eddy current NDT, coils inductance/impedance is normally used as a critical parameter for various industrial applications, such as flaw detection, coating and microstructure sensing. Theoretical derivation, measurements and simulations have been presented to verify the feasibility of the proposed phenomenon.

Computer measurement of the friction of thin metal structure created in PVD technology on the flexible substrate

The paper presents the results of research study on the phenomenon of friction of thin film electroconductive structure created on composite flexible substrate and results of measurement of the friction coefficient. Tribological tests were performed on T-01M tribotester. The measurement tests were conducted according to ASTM G133 standard with a minimum force of 1N. A ball-on-disc friction combination was used. The study was conducted at a fixed temperature of 28 ° C. Due to the nature of the tested samples, non-standard test parameters were used: test time 100 s, data acquisition frequency 10 Hz, slip velocity of the friction node 0.3 m/s on a radius of 11 mm. Based on the obtained results, the friction coefficient of the thin metallic layer Ag and Cu was determined. The obtained mean friction coefficient for a silver layer was 0.59, while for a thin copper layer 0.67. The knowledge of the determined coefficients will allow for effective and optimal use of the textronics materials tested in practical applications. The research methodology does not support determining the usage of the ball-on-disc pair.

On the Design, Manufacture, and Premature Failure of a Metal Mesh Foil Thrust Bearing—How Concepts That Work on Paper, Actually Do Not

Oil-free microturbomachinery (OFT) implements compliant foil bearings because of their minute drag and ability to operate in extreme (high or low) temperature. Prominent to date, bump-foil thrust bearings integrate an underspring thin metal structure that provides resilience and material damping, and while the rotor is airborne, it acts in series with the stiffness and damping of the gas film. The design and manufacturing of foil bearings remain costly as it demands extensive engineering and actual experience. Alternative foil bearing configurations, less costly and easier to manufacture, are highly desirable to enable widespread usage of OFT. This paper details the design and manufacturing of a novel Rayleigh-step metal mesh foil thrust bearing (MMFTB) as well as its testing on a dedicated rig. Metal mesh structures offer significant material structural damping and can be easily procured at a fraction of the cost of a typical bump-foil strip layer. The MMFTB consists of a solid carrier, a number of stacked annular copper mesh sheets (wire diameter = 0.25, 0.3, and 0.41 mm), and a steel top foil (0.127 mm thick) that makes six pads (ID = 50.8 mm, OD =2 ID), each 45 deg in extent. A 3 μm polymer coats each pad, and a photochemical process etches a step 20 μm in height. Static and dynamic load measurements (without rotor speed) demonstrate that the MMFTB has structural stiffness and material damping similar to that of a publicized bump-type foil thrust bearing. A maiden test of the MMFTB with rotor speed of Ω = 15 krpm (∼80 m/s at bearing outer diameter (OD)) proved briefly the bearing operation when applying a tiny thrust load. Further tests with ambient air, a rotor speed of 40 krpm (∼212 m/s at bearing OD), and a very light load/area <7 kPa failed several of the prototype bearings, all exhibiting significant wear on one or more pads. The source of the failure is the inherent unevenness of the metal mesh stacked substructures, thus causing the pads to bulge toward the rotor collar surface before a load applies. A deficient anchoring method exacerbates the unevenness. Incidentally, a high rotor speed induced large windage that lifted the top foils pushing them against the spinning collar. As the bearing moved toward the rotating collar to begin applying thrust, the local high spots rubbed against the collar before a hydrodynamic wedge could form to separate the surfaces. Without a robust sacrificial coating, metal-to-metal contact quickly disfigured the contacting top foil pads, erasing the etched step, and leading to failure. In concept, and on paper, the mesh sheets and the top foil lay flat against the bearing carrier, giving a false sense of uniformity in the design process. In actuality, a designer must consider the manufactured states of the individual components and how they assemble. A redesign of the bearing intends to overcome the existing flaws (highlighted herein) by incorporating a thicker top foil that is well anchored (to better withstand the effects of windage), a robust sacrificial coating, and a hydrodynamic wedge accomplished via a circumferential taper on each pad.

J-Integral Solution for Elastic Fracture Toughness for Plates with Inclined Cracks under Biaxial Loading

Surface cracks with different orientations have been recognized as a major cause of potential failures of thin metal structures, which are often under biaxial loading. It has been known that, for cracked ductile metals, plasticity results in an easing of stress intensity at the crack front and ultimately increases the total fracture toughness of the metal. To enable the use of linear elastic fracture mechanics for ductile material failure prediction, the plastic portion of fracture toughness must be excluded. This paper aims to develop a J-integral based method for determining the elastic fracture toughness of ductile metal plates with inclined cracks under biaxial loading. The derived elastic fracture toughness is a function of the plate and crack geometry, strain-hardening coefficient, yield strength, fracture toughness, biaxiality ratio, and inclination angle. It is found that an increase in yield strength or relative crack depth, or a decrease in Mode-I fracture toughness, leads to a larger ratio of elastic fracture toughness to total fracture toughness. It is also found that the effect of biaxiality ratio and inclination angle on elastic fracture toughness is highly dependent on total fracture toughness. It can be concluded that the developed model can accurately predict the fracture failure of ductile thin metal structures with inclined cracks under biaxial loading.

Fast and Versatile Multiscale Patterning by Combining Template-Stripping with Nanotransfer Printing.

Metal nanostructures are widely used in plasmonic and electronic applications due to their inherent properties. Often, the fabrication of such nanostructures is limited to small areas, as the processing is costly, low-throughput, and comprises harsh fabrication conditions. Here, we introduce a template-stripping based nanotransfer printing method to overcome these limitations. This versatile technique enables the transfer of arbitrary thin film metal structures onto a variety of substrates, including glass, Kapton, silicon, and PDMS. Structures can range from tens of nanometers to hundreds of micrometers over a wafer scale area. The process is organic solvent-free, multilayer compatible, and only takes minutes to perform. The stability of the transferred gold structures on glass exceeds by far those fabricated by e-beam evaporation. Therefore, an adhesion layer is no longer needed, enabling a faster and cheaper fabrication as well as the production of superior nanostructures. Structures can be transferred onto curved substrates, and the technique is compatible with roll-to-roll fabrication; thus, the process is suitable for flexible and stretchable electronics.

Static and Modal Analysis of Low Porosity Thin Metallic Auxetic Structures Using Speckle Interferometry and Digital Image Correlation

This study presents an evaluation of the static and dynamic mechanical behavior of low porosity, ductile two-dimensional auxetic metamaterials. The full in-plane displacement fields and the eigenmodes of different geometric structures were investigated and compared with finite element simulations using speckle interferometry and digital image correlation. The results showed strong agreement, validating the theoretical approach used and establishing a method for testing and quantitatively assessing the performance of negative Poisson ratio structures, and metamaterials in general, for different purposes and fields. The findings of this study also increase our knowledge of elastic instabilities in metallic auxetic structures, with further applications in several engineering fields that can benefit from combining the qualities of ductile materials with additional features typical of these smart structures.

Properties Of Thin Metal Layers Deposited On Textile Composites By Using The Pvd Method For Textronic Applications

Abstract In this paper, the results of mechanical strength tests of thin conductive Ag and Au layers created on Cordura composite substrate using the thermal vapor deposition method are presented. The resistance of the conductive layers to the bending and tensile stresses was tested and changing the surface resistance of the test structures was accepted as a criterion. The layers created on unmodified and plasma-treated surfaces have been examined. As a result of the surface modification, the electrical and mechanical properties of the thin Ag and Au metal structures have been improved. The results of measurements of surface resistance changes during strength tests and SEM microscopic studies of stressed samples indicate the high mechanical strength of the electroconductive layers deposited on Cordura, which may be the basis for the application of such technology in textronics applications.