scholarly journals Characterization of the tunable response of highly strained compliant optical metamaterials

2011 ◽  
Vol 369 (1950) ◽  
pp. 3447-3455 ◽  
Author(s):  
Imogen M. Pryce ◽  
Koray Aydin ◽  
Yousif A. Kelaita ◽  
Ryan M. Briggs ◽  
Harry A. Atwater
Keyword(s):  
Local Strain ◽  
Elastic Response ◽  
Absorption Feature ◽  
Infrared Sensors ◽  
Additional Degree ◽  
Optical Metamaterials ◽  
Vibration Absorption ◽  
Compliant Substrates ◽  
Deformation Limit ◽  
Highly Strained

Metamaterial designs are typically limited to a narrow operating bandwidth that is predetermined by the fabricated dimensions. Various approaches have previously been used to introduce post-fabrication tunability and thus enable active metamaterials. In this work, we exploit the mechanical deformability of a highly compliant polymeric substrate to achieve dynamic, tunable resonant frequency shifts greater than a resonant linewidth. We investigate the effect of metamaterial shape on the plastic deformation limit of resonators. We find that, for designs in which the local strain is evenly distributed, the response is elastic under larger global tensile strains. The plastic and elastic limits of resonator deformation are explored and the results indicate that, once deformed, the resonators operate within a new envelope of elastic response. We also demonstrate the use of coupled resonator systems to add an additional degree of freedom to the frequency tunability and show that compliant substrates can be used as a tool to test coupling strength. Finally, we illustrate how compliant metamaterials could be used as infrared sensors, and show enhancement of an infrared vibration absorption feature by a factor of 225.

scholarly journals Indirect light absorption model for highly strained silicon infrared sensors

2021 ◽  
Vol 130 (5) ◽  
pp. 055105
Author(s):  
Nicolas Roisin ◽  
Guillaume Brunin ◽  
Gian-Marco Rignanese ◽  
Denis Flandre ◽  
Jean-Pierre Raskin
Keyword(s):  
Light Absorption ◽  
Strained Silicon ◽  
Absorption Model ◽  
Infrared Sensors ◽  
Highly Strained

scholarly journals Scale Effects in Orthotropic Composite Assemblies as Micropolar Continua: A Comparison between Weak- and Strong-Form Finite Element Solutions

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 758 ◽  
Author(s):  
Lorenzo Leonetti ◽  
Nicholas Fantuzzi ◽  
Patrizia Trovalusci ◽  
Francesco Tornabene
Keyword(s):  
Finite Element ◽  
Scale Effects ◽  
Kinematic Model ◽  
Elastic Response ◽  
Actual Behavior ◽  
Orthotropic Composite ◽  
Additional Degree ◽  
Micropolar Continua ◽  
Orthotropic Composites ◽  
Micropolar Materials

The aim of the present work was to investigate the mechanical behavior of orthotropic composites, such as masonry assemblies, subjected to localized loads described as micropolar materials. Micropolar models are known to be effective in modeling the actual behavior of microstructured solids in the presence of localized loads or geometrical discontinuities. This is due to the introduction of an additional degree of freedom (the micro-rotation) in the kinematic model, if compared to the classical continuum and the related strain and stress measures. In particular, it was shown in the literature that brick/block masonry can be satisfactorily modeled as a micropolar continuum, and here it is assumed as a reference orthotropic composite material. The in-plane elastic response of panels made of orthotropic arrangements of bricks of different sizes is analyzed herein. Numerical simulations are provided by comparing weak and strong finite element formulations. The scale effect is investigated, as well as the significant role played by the relative rotation, which is a peculiar strain measure of micropolar continua related to the non-symmetry of strain and work-conjugated stress. In particular, the anisotropic effects accounting for the micropolar moduli, related to the variation of microstructure internal sizes, are highlighted.

Dilute Group III-AsN: Bonding of Nitrogen in GaInAsN and AlGaAsN on GaAs and Realization of Long Wavelength (2.3 μm) GaInAsN QWs on InP

2002 ◽  
Vol 744 ◽  
Author(s):  
D. Serries ◽  
T. Geppert ◽  
K. Köhler ◽  
P. Ganser ◽  
J. Wagner
Keyword(s):  
Quantum Wells ◽  
Cohesive Energy ◽  
Local Strain ◽  
Indium Content ◽  
Group Iii ◽  
Long Wavelength ◽  
Inp Substrate ◽  
High Indium Content ◽  
Nitrogen Bonds ◽  
Highly Strained

ABSTRACTRecent results on the local bonding of nitrogen in dilute GaInAsN and AlGaAsN on GaAs are reviewed, revealing that bonding of nitrogen in GaInAsN is controlled by an interplay between bond cohesive energy and reduction of local strain. Thus, III-N bonding in GaInAsN can be changed from Ga-N to In-N by post-growth thermal annealing. In AlGaAsN, in contrast, nitrogen bonds preferentially to Al, i.e. Al-N bonds are formed, due to the much larger cohesive energy of the Al-N bond. Further, results on indium-rich highly strained GaInAsN quantum wells on InP substrate are reported, showing room-temperature photoluminescence at wavelengths up to 2.3 μm. This result demonstrates the potential of high indium content dilute GaInAsN for InP-based long wavelength diode lasers.

scholarly journals Simple and accurate methods for quantifying deformation, disruption, and development in biological tissues

2014 ◽  
Vol 11 (100) ◽  
pp. 20140685 ◽  
Author(s):  
John J. Boyle ◽  
Maiko Kume ◽  
Matthew A. Wyczalkowski ◽  
Larry A. Taber ◽  
Robert B. Pless ◽  
...  
Keyword(s):  
Tracking Error ◽  
Computational Cost ◽  
Local Strain ◽  
Biological Tissues ◽  
Localized Deformation ◽  
General Technique ◽  
Simple Method ◽  
Strain Estimation ◽  
Concentrated Deformation ◽  
Highly Strained

When mechanical factors underlie growth, development, disease or healing, they often function through local regions of tissue where deformation is highly concentrated. Current optical techniques to estimate deformation can lack precision and accuracy in such regions due to challenges in distinguishing a region of concentrated deformation from an error in displacement tracking. Here, we present a simple and general technique for improving the accuracy and precision of strain estimation and an associated technique for distinguishing a concentrated deformation from a tracking error. The strain estimation technique improves accuracy relative to other state-of-the-art algorithms by directly estimating strain fields without first estimating displacements, resulting in a very simple method and low computational cost. The technique for identifying local elevation of strain enables for the first time the successful identification of the onset and consequences of local strain concentrating features such as cracks and tears in a highly strained tissue. We apply these new techniques to demonstrate a novel hypothesis in prenatal wound healing. More generally, the analytical methods we have developed provide a simple tool for quantifying the appearance and magnitude of localized deformation from a series of digital images across a broad range of disciplines.

Effective Compliance of an Elastic Inhomogeneity With Non-Uniform Strain

2005 ◽  
Author(s):  
Larissa Gorbatikh
Keyword(s):  
Material Properties ◽  
Local Strain ◽  
Circular Inclusion ◽  
Uniform Strain ◽  
Elastic Response ◽  
Strong Interactions ◽  
Material Microstructure ◽  
Uniform Stress Field ◽  
Debonded Interface ◽  
Elastic Inhomogeneity

A method is proposed to estimate contribution of an elastic inhomogeneity into the overall strain of the material for the case when strain inside the inhomogeneity is not uniform. Uniform strain is a common situation when the inhomogeneity has an ellipsoidal shape and placed into the uniform stress field. However, the assumption of uniformity is inadequate in many applications when geometrical irregularities of the inhomogeneity, surface effects as well as interactions with other inhomogeneities cause local strain variations in the medium. The proposed method may have far reaching implications when impact of local strain variations on the material overall elastic response is of interest. For example, it may bring insight on how to account for strong interactions between inhomogeneities when predicting material properties and how to mobilize these interactions to achieve better properties. It is well known that interactions may produce stiffening and toughening effects depending on the material microstructure. The compliance contribution tensor is found to be dependent on the boundary displacements of the inhomogeneity and material properties. To illustrate the method we calculated elastic compliances of (1) a circular inclusion with perfectly bonded interface (test problem), (2) a circular inclusion with partially debonded interface, and (3) two strongly interacting cracks in parallel setting.

Highly Strained Compliant Optical Metamaterials with Large Frequency Tunability

Nano Letters ◽  
2010 ◽  
Vol 10 (10) ◽  
pp. 4222-4227 ◽  
Author(s):  
Imogen M. Pryce ◽  
Koray Aydin ◽  
Yousif A. Kelaita ◽  
Ryan M. Briggs ◽  
Harry A. Atwater
Keyword(s):  
Optical Metamaterials ◽  
Frequency Tunability ◽  
Highly Strained ◽  
Large Frequency

scholarly journals Erratum: “Indirect light absorption model for highly strained silicon infrared sensors” [J. Appl. Phys. 130, 055105 (2021)]

2021 ◽  
Vol 130 (20) ◽  
pp. 209901
Author(s):  
Nicolas Roisin ◽  
Guillaume Brunin ◽  
Gian-Marco Rignanese ◽  
Denis Flandre ◽  
Jean-Pierre Raskin
Keyword(s):  
Light Absorption ◽  
Strained Silicon ◽  
Absorption Model ◽  
Infrared Sensors ◽  
Highly Strained

scholarly journals Strain-accumulation mechanisms in sands under isotropic stress

2019 ◽  
Vol 16 (6) ◽  
pp. 1139-1150
Author(s):  
A Sajeva ◽  
S Capaccioli ◽  
H Cheng
Keyword(s):  
Local Strain ◽  
Unconsolidated Sediments ◽  
Elastic Response ◽  
Strain Accumulation ◽  
Grain Rotation ◽  
Petrophysical Parameters ◽  
Coordination Numbers ◽  
Global Strain ◽  
Effective Medium Theories ◽  
Accumulation Mechanism

Abstract Determining the pressure dependence of dynamic moduli in unconsolidated sediments is still an open problem in applied geophysics. This is because several petrophysical parameters affect the elastic response of the granular medium during compression. Effective medium theories based on the Hertz–Mindlin contact law estimate the effective moduli from petrophysical parameters. Among them, the Pride and Berryman model assumes that new contacts between grains are progressively created during compression. Furthermore, the gaps around rattlers are distributed following a power law with distance and the global strain can change either linearly or quadratically with the local strain. This identifies two types of strain accumulation. Quadratic strain accumulation is associated with grain rotation. We simplified this model by assuming a flat distribution of gaps around rattlers and we applied this simplified model to published ultrasonic measurements. By means of these measurements, we studied how the strain-accumulation mechanism affects the coordination number during isotropic compression. The coordination numbers were estimated by applying a DEM-based correction to the average-strain model. We observe that the majority of the experimental trends lay between the linear and the quadratic accumulation trends. Based on this result, we assume that the strain accumulation is a combination of the two mechanisms and we propose a formula to estimate the contribution of each mechanism. Furthermore, we note that, in the studied datasets, rotation affects larger grains (diameter approximately 500 μm) more than smaller grains (diameter approximately 100 μm). If further validated, this correlation could guide the determination of pressure trends for sands.

Experimental Study on Elastic Stiffness of Kaolinite Clay

2013 ◽  
Vol 813 ◽  
pp. 395-398
Author(s):  
Keeratikan Piriyakul
Keyword(s):  
Shear Modulus ◽  
Local Strain ◽  
Small Strain ◽  
Elastic Response ◽  
Triaxial Tests ◽  
Clay Sample ◽  
Bender Element ◽  
Kaolinite Clay ◽  
Strain Measurements ◽  
Elastic Shear

This paper presents a study on the elastic shear modulus of Kaolinite clay at very small strains under isotropic stress from triaxial tests. The Kaolinite clay sample is subjected to an isotropic stress of 100, 200 and 400 kPa. In this very small strain domain where strain is less than 10-3 %, the behaviour of clay soil shows an elastic response. In conventional triaxial test, an initial shear modulus, G0, can be measured using an external strain measurement device. Nevertheless, there is an advantage to mount local strain sensors directly on a clay sample in order to obtain more accurate measurement of G0. Also the G0 can be measured by bender elements through propagation of an elastic shear wave. Therefore in this research G0 can be obtained by external, local strain measurements and bender element tests. These results of G0 in the very small strain region are compared and show that there is a good agreement between the results from local strain measurements and bender element tests.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

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