scholarly journals Programmable and robust static topological solitons in mechanical metamaterials

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yafei Zhang ◽  
Bo Li ◽  
Q. S. Zheng ◽  
Guy M. Genin ◽  
C. Q. Chen
Keyword(s):  
Static Compression ◽  
Single Wave ◽  
Topological Solitons ◽  
Spatial And Temporal Scales ◽  
Topological Excitations ◽  
Mechanical Metamaterials ◽  
Wide Range ◽  
Intrinsic Length ◽  
Chemical And Biological Systems ◽  
Quasi Static Compression

AbstractSolitary, persistent wave packets called solitons hold potential to transfer information and energy across a wide range of spatial and temporal scales in physical, chemical, and biological systems. Mechanical solitons characteristically emerge either as a single wave packet or uncorrelated propagating topological entities through space and/or time, but these are notoriously difficult to control. Here, we report a theoretical framework for programming static periodic topological solitons into a metamaterial, and demonstrate its implementation in real metamaterials computationally and experimentally. The solitons are excited by deformation localizations under quasi-static compression, and arise from buckling-induced kink-antikink bands that provide domain separation barriers. The soliton number and wavelength demonstrate a previously unreported size-dependence, due to intrinsic length scales. We identify that these unanticipated solitons stem from displacive phase transitions with periodic topological excitations captured by the well-known $${\varphi }^{4}$$φ4 theory. Results reveal pathways for robust regularizations of stochastic responses of metamaterials.

scholarly journals Temporal Variations of the Turbulence Profiles at the Sayan Solar Observatory Site

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 499 ◽  
Author(s):  
Artem Shikhovtsev ◽  
Pavel Kovadlo ◽  
Vladimir Lukin
Keyword(s):  
Atmospheric Turbulence ◽  
Temporal Variability ◽  
Low Frequency ◽  
Temporal Variations ◽  
Solar Observatory ◽  
Vertical Profiles ◽  
Spatial And Temporal Scales ◽  
Atmospheric Disturbances ◽  
Wide Range ◽  
The Mean

The paper focuses on the development of the method to estimate the mean characteristics of the atmospheric turbulence. Using an approach based on the shape of the energy spectrum of atmospheric turbulence over a wide range of spatial and temporal scales, the vertical profiles of optical turbulence are calculated. The temporal variability of the vertical profiles of turbulence under different low-frequency atmospheric disturbances is considered.

scholarly journals Analysis of the Strain and Stress Fields of Cardboard Box during Compression by 3D Digital Image Correlation

2010 ◽  
Vol 24-25 ◽  
pp. 103-108 ◽  
Author(s):  
Jeremie Viguié ◽  
P.J.J. Dumont ◽  
P. Vacher ◽  
Laurent Orgéas ◽  
I. Desloges ◽  
...  
Keyword(s):  
Compression Strength ◽  
Compressive Loading ◽  
Image Correlation ◽  
Parallel Plates ◽  
Static Compression ◽  
3D Digital Image Correlation ◽  
Plastic Materials ◽  
Semi Empirical ◽  
And Storage ◽  
Quasi Static Compression

Corrugated boards with small flutes appear as good alternatives to replace packaging folding boards or plastic materials due their small thickness, possibility of easy recycling and biodegradability. Boxes made up of these materials have to withstand significant compressive loading conditions during transport and storage. In order to evaluate their structural performance, the box compression test is the most currently performed experiment. It consists in compressing an empty container between two parallel plates at constant velocity. Usually it is observed that buckling phenomena are localized in the box panels, which bulge out during compression [1]. At the maximum recorded compression force, the deformation localises around the box corners where creases nucleate and propagate. This maximum force is defined as the quasi-static compression strength of the box. The prediction of such strength is the main topic of interest of past and current research works. For example, the box compression behaviour of boxes was studied by Mc Kee et al. [2] and Urbanik [3], who defined semi-empirical formula to predict the box compression strength, as well as by Beldie et al. [4] and Biancolini et al. [5] by finite element simulations. But comparisons of these models with experimental results remain rather scarce and limited.

Experimental and theoretical study of sandwich composites with Z-pins under quasi-static compression loading

2021 ◽  
pp. 136943322110073
Author(s):  
Erdem Selver ◽  
Gaye Kaya ◽  
Hussein Dalfi
Keyword(s):  
Vinyl Ester ◽  
Failure Modes ◽  
Critical Role ◽  
Sandwich Composites ◽  
Test Results ◽  
Compressive Properties ◽  
Element Analysis ◽  
Static Compression ◽  
Quasi Static Compression ◽  
Good Agreement

This study aims to enhance the compressive properties of sandwich composites containing extruded polystyrene (XPS) foam core and glass or carbon face materials by using carbon/vinyl ester and glass/vinyl ester composite Z-pins. The composite pins were inserted into foam cores at two different densities (15 and 30 mm). Compression test results showed that compressive strength, modulus and loads of the sandwich composites significantly increased after using composite Z-pins. Sandwich composites with 15 mm pin densities exhibited higher compressive properties than that of 30 mm pin densities. The pin type played a critical role whilst carbon pin reinforced sandwich composites had higher compressive properties compared to glass pin reinforced sandwich composites. Finite element analysis (FE) using Abaqus software has been established in this study to verify the experimental results. Experimental and numerical results based on the capabilities of the sandwich composites to capture the mechanical behaviour and the damage failure modes were conducted and showed a good agreement between them.

Evaluation of Belleville Springs and Damping Through Static Cyclic Loading “Hysteresis” for pVARD Optimization: Part-I

2021 ◽  
Author(s):  
Abdelsalam Abugharara ◽  
Stephen Butt
Keyword(s):  
Data Analysis ◽  
Cyclic Loading ◽  
Dynamic Compression ◽  
Range Data ◽  
Compression Tests ◽  
Rotary Drilling ◽  
Static Compression ◽  
Drilling Performance ◽  
Wide Range ◽  
Compression Hysteresis

Abstract One unconventional application that researchers have been investigating for enhancing drilling performance, has been implemented through improving and stabilizing the most effective downhole drilling parameters including (i) increasing downhole dynamic weight on bit (DDWOB), (ii) stabilizing revolution per minutes (rpm), (iii) minimizing destructive downhole vibrations, among many others. As one portion of a three-part-research that consists of a comprehensive data analysis and evaluation of a static compression hysteresis, dynamic compression hysteresis, and corresponding drilling tests, this research investigates through static cyclic loading “Hysteresis” of individual and combined springs and damping the functionality of the passive Vibration Assisted Rotary Drilling (pVARD) tool that could be utilized towards enhancing the drilling performance. Tests are conducted on the two main pVARD tool sections that include (i) Belleville springs, which represent the elasticity portion and (ii) the damping section, which represents the viscous portion. Firstly, tests were conducted through static cyclic loading “Hysteresis” of (i) a mono elastic, (ii) a mono viscus, and (iii) dual elastic-viscus cyclic loading scenarios for the purpose of further examining pVARD functionality. For performing static compression tests, a calibrated geomechanics loading frame was utilized, and various spring stacking of different durometer damping were tested to seek a wide-range data and to provide a multi-angle analysis. Results involved analyzing loading and displacement relationships of individual and combined springs and damping are presented with detailed report of data analysis, discussion, and conclusions.

A NONLINEAR STRAIN-DEPENDENT VARIABLE-ORDER FRACTIONAL MODEL WITH APPLICATIONS TO ALUMINUM FOAMS

Fractals ◽  
2021 ◽  
Author(s):  
WEI CAI ◽  
PING WANG
Keyword(s):  
Power Law ◽  
Variable Order ◽  
Aluminum Foams ◽  
Static Compression ◽  
Fractional Model ◽  
Comparative Results ◽  
The Impact ◽  
Strain Responses ◽  
Strain Dependent ◽  
Quasi Static Compression

In this paper, a power-law strain-dependent variable order is first incorporated into the fractional constitutive model and employed to describe mechanical behaviors of aluminum foams under quasi-static compression and tension. Comparative results illustrate that power-law strain-dependent variable order is capable of better describing stress–strain responses compared with the traditional linear one. The evolution of fractional order along with the porosities or relative densities can be well qualitatively interpreted by its physical meaning. Furthermore, the model is also extended to characterize the impact behaviors under large constant strain rates. It is observed that fractional model with sinusoidal variable order agrees well with the experimental data of aluminum foams with impact and non-impact surfaces.

An Experimental Study on Dynamic Constitutive Relationship of 7075-T651 Aluminum Alloy

2013 ◽  
Vol 816-817 ◽  
pp. 84-89
Author(s):  
Yong Gang Kang ◽  
Yuan Yang ◽  
Jie Huang ◽  
Jing Hang Zhu
Keyword(s):  
Aluminum Alloy ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Flow Behavior ◽  
Constitutive Relationship ◽  
Hopkinson Pressure Bar ◽  
Experiment Data ◽  
Static Compression ◽  
Quasi Static Compression

7075-T651 aluminum alloy are widely used in aeronautical applications such as wing panels, but there is no corresponding constitutive model for it now. In this paper, the flow behavior of 7050-T651 aluminum alloy was investigated by Split Hopkinson Pressure Bar (SHPB) and quasi-static compression experiment system. The strain hardening parameters were obtained by quasi-static compression experiment data, and the strain rate hardening parameters at various strain rates (1000-3000s-1) and room temperature, and the thermal softening parameter at various temperatures (20-300°C) where strain rate is 3000s-1 were obtained by SHPB experiment data. Then the constitutive equation of 7075-T651 aluminum alloy is obtained based on Johnson-Cook constitutive equation model.

scholarly journals Prediction of Crushing Response for Metal Hexagonal Honeycomb under Quasi-Static Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xinyu Geng ◽  
Yufei Liu ◽  
Wei Zheng ◽  
Yongbin Wang ◽  
Meng Li
Keyword(s):  
Mathematical Models ◽  
Static Loading ◽  
Theoretical Basis ◽  
Theoretical Models ◽  
Excellent Correlation ◽  
Static Compression ◽  
Out Of Plane ◽  
Plane Direction ◽  
Element Theory ◽  
Quasi Static Compression

To provide a theoretical basis for metal honeycombs used for buffering and crashworthy structures, this study investigated the out-of-plane crushing of metal hexagonal honeycombs with various cell specifications. The mathematical models of mean crushing stress and peak crushing stress for metal hexagonal honeycombs were predicted on the basis of simplified super element theory. The experimental study was carried out to check the accuracy of mathematical models and verify the effectiveness of the proposed approach. The presented theoretical models were compared with the results obtained from experiments on nine types of honeycombs under quasi-static compression loading in the out-of-plane direction. Excellent correlation has been observed between the theoretical and experimental results.

scholarly journals Land–atmosphere interactions in the tropics

2019 ◽  
Author(s):  
Pierre Gentine ◽  
Adam Massmann ◽  
Benjamin R. Lintner ◽  
Sayed Hamed Alemohammad ◽  
Rong Fu ◽  
...  
Keyword(s):  
Land Surface ◽  
Deep Convection ◽  
Lower Troposphere ◽  
Surface Fluxes ◽  
Surface Radiation ◽  
Spatial And Temporal Scales ◽  
Wide Range ◽  
Shallow Clouds ◽  
The Tropics ◽  
The Impact

Abstract. The continental tropics play a leading role in the terrestrial water and carbon cycles. Land–atmosphere interactions are integral in the regulation of surface energy, water and carbon fluxes across multiple spatial and temporal scales over tropical continents. We review here some of the important characteristics of tropical continental climates and how land–atmosphere interactions regulate them. Along with a wide range of climates, the tropics manifest a diverse array of land–atmosphere interactions. Broadly speaking, in tropical rainforests, light and energy are typically more limiting than precipitation and water supply for photosynthesis and evapotranspiration; whereas in savanna and semi-arid regions water is the critical regulator of surface fluxes and land–atmosphere interactions. We discuss the impact of the land surface, how it affects shallow clouds and how these clouds can feedback to the surface by modulating surface radiation. Some results from recent research suggest that shallow clouds may be especially critical to land–atmosphere interactions as these regulate the energy budget and moisture transport to the lower troposphere, which in turn affects deep convection. On the other hand, the impact of land surface conditions on deep convection appear to occur over larger, non-local, scales and might be critically affected by transitional regions between the climatologically dry and wet tropics.

scholarly journals Compressive Property of an Auxetic-Knitted Composite Tube Under Quasi-Static Loading

2020 ◽  
Vol 20 (2) ◽  
pp. 101-109 ◽  
Author(s):  
Andrews Boakye ◽  
Rafui King Raji ◽  
Pibo Ma ◽  
Honglian Cong
Keyword(s):  
Energy Absorption ◽  
Compression Test ◽  
Impact Loading ◽  
Static Loading ◽  
Fiber Content ◽  
Compressive Property ◽  
Static Compression ◽  
Arrow Head ◽  
Composite Tube ◽  
Quasi Static Compression

AbstractThis research investigates the compressive property of a novel composite based on a weft-knitted auxetic tube subjected to a quasi-static compression test. In order to maximize the influence of the fiber content on the compression test, a Kevlar yarn was used in knitting the tubular samples using three different auxetic arrow-head structures (i.e. 4 × 4, 6 × 6 and 8 × 8 structure). A quasi-static compression test was conducted under two different impact loading speeds (i.e. 5 mm/min and 15 mm/min loading speed). The results indicate that the energy absorption (EA) property of the auxetic composite is highly influenced by the auxeticity of the knitted tubular fabric.

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