KEYWORDS: Resistance, Scanning electron microscopy, Adhesives, Transducers, 3D modeling, Sensors, Electron microscopes, Data modeling, Lithium, Aerospace engineering
We investigated the determinations by the micro-morphology of the sensitive grids of resistance strain gauge on their stress distributions. The micro-morphologies of the sidewalls for four typical resistance strain gauges were observed by scanning electron microscopy (SEM), and then the microscopic images were binarized to obtain the micromorphological characteristics of the sensitive grids. The observation shows that the sidewalls of the sensitive grids have periodic microstructures. A geometrical model of sinusoidal contour and a strain transfer model was established following the observed micro-morphological features. The influence of the amplitude and period parameters of the sinusoidal contour on the stress level of the sensitive grid was calculated numerically. The results show that the maximum stress increases, however the average stress decreases, with the increase of the profile amplitude with a certain periodicity. For a sinusoidal profile having a fixed amplitude, its maximum stress decreases with the increase of the cycle, wherever the average stress increases. The smaller side wall defects and longer interval in a sensitive grid would make the stress distribution more uniform. The obtained results would provide guidance for the fabrication of the resistance strain gauge.
The strain transfer characteristics of resistance strain-type transducer were theoretically investigated. A resistance straintype transducer was modeled to be a four-layer and two-glue (FLTG) structure model, which comprises successively an elastomer, a ground adhesive, a substrate layer, an upper adhesive, a sensitive grids layer, and a polymer cover. The strain transfer progress in a resistance strain-type transducer was described by the FLTG structure model. The strain transitional zone (STZ) was defined and the strain transfer ratio (STR) of the FLTG structure was formulated. The dependence of the STR and STZ on both the structural sizes and material parameters were calculated. The results indicate that the ground adhesive (including its thickness, and shear modulus) have a greater influence on the strain transitional zone ratio and strain transitional zone. In order to ensure a higher sensitivity of the resistance strain-type transducer, the ground adhesive layer should be as thin as possible, while its shear modulus should be as large as possible. Selecting a ground adhesive with a large elasticity modulus can effectively reduce the influence of the thickness of the ground adhesive on the strain transfer ratio.
This paper proposes a new strategy of extracting boundary points from scanning point cloud (SPC) data of sheet metal parts (SMPs). This strategy is suitable for bending SMPs with slowly changing surfaces. To cope with the problem that the SMP is too thin to have enough points of its lateral surface to be calculated for the boundary outline, the boundary points are obtained by moving ridge points which is the maximum curvature points on the marginal of parts along theoretical position direction. In this article, the strategy is explained firstly and then carried out on two different experimental SMPs. The strategy contains several steps. Firstly, we construct a slice set called multiple direction slices (MDS) along a curve fitted by boundary points of SPC. Then marginal point data (MPD) is obtained completely and accurately by MDS. And then the chamfer arc data is extracted from MPD by setting identification model of chamfer arc’s two endpoints. Then the ridge points which are the maximal curvature points of chamfer arc data are picked out from chamfer arc data. Finally, by moving the ridge points along a certain direction for a fixed distance, the boundary points are calculated out. Two experiments are carried out to identify position error and form error of the extracted boundary points. The measurement results of boundary outlines of a 6mm thick SMP from a three coordinate measuring machine (CMM) is taken as reference in the first experiment. The second experiment regards theoretical boundary outline as reference. Both two experiments demonstrate the effectiveness of the strategy.
Plasmonic optics is an emerging research field that combines electronics and photonics with nanostructures. It studies the interactions between electromagnetic waves and matter at the nanoscale. This Tutorial Text provides an introduction to plasmonic optics with distinct concepts and typical applications. Readers will learn about the physics and applications of nanoscale photophysics, leading to better understanding of the fundamental properties of photons in nanostructure materials. Topics include the physical basis of plasmonics, the extraordinary transmission of nanohole arrays, scattering enhancement of nanoparticles, perfect absorption of metamaterials, and nanoantennas for light radiation.
The aim of this work is to present a multi-band absorption metamaterials. One dual cross-shape perfect absorber
metamaterials (PAMs) was developed to obtain multi-band spectrum at mid-infrared. The PAMs possess three distinct
resonant peaks standing independently, which are attributed to the polarization sensitive excitation of plasmonic
resonance. The optical parameters retrieved by S-parameters method were investigated, which provides a satisfactory
qualitative description of the multiple-band spectra responses. On the other hand, the near-field plasmonic behaviors and
redistribution of the electromagnetic field were probed theoretically and numerically into the PAMs structure, which also
explains the observed absorption behavior of the PAMs ensemble based upon the microscopic perspective. The multiplex
spectrum enables the infrared perfect absorber metamaterials (PAMs) a powerful tool for direct access to vibrational
fingerprints of single molecular structure.
Optical antennas hold great promise for increasing the efficiency of photovoltaics, light-emitting devices, and optical sensors1. This paper discusses one strategy to achieve frequency selective detection at mid-infrared region, which utilize the plasmonic absorption nanoantenna. The infrared devices realized by such nanoantenna array have merits such as more flexibility of frequency selectivity, and its highlights of polarization properties, which will develop increased functionality for next generation focal plane arrays2. We investigated one example of such nanoantenna devices to tune its plasmonic resonance for achieving frequency selectivity and polarization properties. We also demonstrated its multiplex band absorption, and one tactics to broaden its absorption spectrum. The broad infrared sensitivity of nanoantenna devices would enable multiplex bands infrared imaging detectors. The optical properties of such examples are simulated and measurement which shows perfect absorption in certainty frequency-band. By exploiting nanoantenna as light-harvesting and carrier generation element, plasmonic absorption nanoantenna devices would realize both polarization- and wavelength-selective detection, which would overcome the band gap limitations of existing semiconducting materials.
The multiplex-bands absorption of sandwich-structure metamaterials based metal- dielectric- metal scheme are
investigated numerically and experimentally. The optical properties of cross-shape antenna perfect absorber metamaterials are demonstrated in mid-IR electromagnetic (EM) wave. The dual-band perfect absorber with polarization
independence is observed under normal incidence. In order to understand the EM properties of dual-band perfect absorber, the plasmonic excitation and the induced current distribution were clarified for both peaks. The simulation results clearly show that the absorption bands are independently governed by the size of each part of the patterned
nanostructure. The repositioning of two near-perfect absorption peaks possesses a linear relationship. This allows for a
flexible reconfigurability over the entire near-infrared regime. Furthermore, in order to obtain multiplex-bands spectral
absorption response, two cross-shape antennas are connected to form one dumbbell antenna. The three perfect-absorption peaks can be controlled by the individual dipole antenna elements in the conditions of polarization incident EM wave.
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