Ultrasensitive micro/nanocrack-based graphene nanowall strain sensors derived from the substrate's Poisson's ratio effect

2020 ◽  
Vol 8 (20) ◽  
pp. 10310-10317
Author(s):  
Hongyan Sun ◽  
Chen Ye ◽  
Gang Zhao ◽  
Huan Zhang ◽  
Zhiduo Liu ◽  
...  
Keyword(s):  
Thin Film ◽  
Human Body ◽  
Poisson’S Ratio ◽  
Strain Sensors ◽  
Poisson's Ratio ◽  
Ratio Effect ◽  
Electronic Skin ◽  
Acoustic Signature ◽  
Signature Recognition ◽  
Ultrahigh Sensitivity

Thin film strain sensors composed of GNWs grown by MPCVD, showing ultrahigh sensitivity which can be applied for acoustic signature recognition, as well as electronic skin devices to detect both subtle and large motions of the human body.

Measurement of Young's Modulus and Poisson's Ratio of Thin Film by Combination of Bulge Test and Nano-Indentation

2008 ◽  
Vol 33-37 ◽  
pp. 969-974 ◽  
Author(s):  
Bong Bu Jung ◽  
Seong Hyun Ko ◽  
Hun Kee Lee ◽  
Hyun Chul Park
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Applied Pressure ◽  
Indentation Test ◽  
Poisson's Ratio ◽  
Bulge Test ◽  
Nano Indentation

This paper will discuss two different techniques to measure mechanical properties of thin film, bulge test and nano-indentation test. In the bulge test, uniform pressure applies to one side of thin film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties such as the elastic modulus and the residual stress. Nano-indentation measurements are accomplished by pushing the indenter tip into a sample and then withdrawing it, recording the force required as a function of position. . In this study, modified King’s model can be used to estimate the mechanical properties of the thin film in order to avoid the effect of substrates. Both techniques can be used to determine Young’s modulus or Poisson’s ratio, but in both cases knowledge of the other variables is needed. However, the mathematical relationship between the modulus and Poisson's ratio is different for the two experimental techniques. Hence, achieving agreement between the techniques means that the modulus and Poisson’s ratio and Young’s modulus of thin films can be determined with no a priori knowledge of either.

A Reexamination of the Extraction of Material Properties Using Nanoindentation

2008 ◽  
Author(s):  
B. Poon ◽  
D. Rittel ◽  
G. Ravichandran
Keyword(s):  
Contact Area ◽  
Material Properties ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Nanoindentation Test ◽  
Displacement Curve ◽  
Elastic Solids ◽  
Ratio Effect ◽  
Elastic Plastic ◽  
Tip Radius

The paper reexamines the extraction of material properties using nanoindentation for linearly elastic and elastic-plastic materials. The paper considers indentation performed using a rigid conical indenter, as follows. Linearly elastic solids: The reduction of nanoindentation test data of elastic solids is usually processed using Sneddon’s relation [1], which assumes a linearly elastic infinite half space and an infinitely sharp indenter tip. These assumptions are violated in practical indentation experiments. Since most of the research on the extraction of material properties relies heavily on numerical simulations, we used them to investigate the specimen dimensions required for it to qualify as an infinite body, and the indentation conditions for finite tip radius effect to be negligible. The outcome of this part is firstly, the definition of a “converged” 2D geometry so that additional magnification of the numerical model does not influence the load-displacement curve, and secondly, an explicit relationship between the measured load and displacement that takes into account the finite tip radius. Elastic-plastic solids: Here, the main data reduction technique was proposed by Pharr et al. [2], assuming elastic unloading of a plastic nanoindentation. We investigated the effects of finite tip radius in elastic-plastic indentations and found that the accuracy of the prediction is currently limited by the accurate determination of the projected contact area. This point will be discussed and a new experimental technique to measure the projected contact area will be proposed. The Poisson’s ratio effect in elastic-plastic indentations is found to be different from the linearly elastic case. This leads to the discussion on the applicability of the correction factor (for Poisson’s ratio effect) derived in linear elastic indentations, on elastic-plastic indentations. Finally, a technique to obtain an upper bound estimate of the yield stress for the indented elastic-plastic material (which is an exact estimation for non-hardening materials), will be presented.

Deformation behavior of auxetic woven fabric made of foldable geometry in different tensile directions

2020 ◽  
Vol 91 (1-2) ◽  
pp. 87-99
Author(s):  
Hasan Kamrul ◽  
Weiguo Dong ◽  
Adeel Zulifqar ◽  
Shuaiquan Zhao ◽  
Minglonghai Zhang ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Tensile Deformation ◽  
Tensile Loading ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Ratio Effect ◽  
Negative Poisson's Ratio ◽  
Principal Directions

Auxetic woven fabrics made with special geometrical structures have gained the interest of textile scientists in recent years. This paper reports a study on auxetic woven fabric based on a double-directional parallel in-phase zig-zag foldable geometrical structure. Such a fabric has been already produced and investigated for its negative Poisson's ratio effect in two principal directions (weft and warp directions). However, its negative Poisson's ratio effect in biased tensile directions as well as under repeated tensile loading conditions has not been studied yet. Therefore, in this paper, these two limitations are addressed. The auxetic woven fabric was firstly fabricated, and then subjected not only to tensile tests in different tensile directions, including two principle directions and three biased directions, but also to repeated tensile loading. It was found that both the negative Poisson's ratio effect and the resistance to tensile deformation are dependent upon the tensile direction, and the highest negative Poisson's ratio effect and higher resistance to tensile deformation are obtained in two principal directions.

scholarly journals Design and Prediction of a Novel Two-Dimensional Carbon Nanostructure with In-Plane Negative Poisson’s Ratio

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Kun Yuan ◽  
Meng-Yang Li ◽  
Yan-Zhi Liu ◽  
Ren-Zhong Li
Keyword(s):  
Mechanical Properties ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Mechanical Stability ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Two Dimensional ◽  
Carbon Nanostructure ◽  
Ratio Effect ◽  
Negative Poisson's Ratio

The intrinsic negative Poisson’s ratio effect in 2-dimensional nanomaterials have attracted a lot of research interests due to its superior mechanical properties, and new mechanisms have emerged in the nanoscale. In this paper, we designed a novel graphyne-like two-dimensional carbon nanostructure with a “butterfly” shape (GL-2D-1) and its configuration isomer with a “herring-bone” form (GL-2D-2) by means of density functional theoretical calculation and predicted their in-plane negative Poisson’s ratio effect and other mechanical properties. Both GL-2D-1 and GL-2D-2 present a significant negative Poisson’s ratio effect under different specific strains conditions. By contrast, GL-2D-2 presents a much stronger negative Poisson’s ratio effect and mechanical stability than does GL-2D-1. It is hoped that this work could be a useful structural design strategy for the development of the 2D carbon nanostructure with the intrinsic negative Poisson’s ratio.

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