Chemistry of Sulfur Chain and Design of Dynamic Soft Materials Using Rotaxane Effect of Rotaxane-Crosslink (1)

2021 ◽  
Vol 94 (1) ◽  
pp. 11-17
Author(s):  
Toshikazu TAKATA
Keyword(s):  
Soft Materials

Hierarchical Structures in Soft Materials

2018 ◽  
Vol 91 (10) ◽  
pp. 365-369
Author(s):  
Mikihito TAKENAKA
Keyword(s):  
Hierarchical Structures ◽  
Soft Materials

scholarly journals Depth-Sensing Indentation as a Micro- and Nanomechanical Approach to Characterisation of Mechanical Properties of Soft, Biological, and Biomimetic Materials

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
Nikolay V. Perepelkin ◽  
Feodor M. Borodich ◽  
Alexander E. Kovalev ◽  
Stanislav N. Gorb
Keyword(s):  
Review Paper ◽  
Soft Materials ◽  
Data Fitting ◽  
Depth Sensing ◽  
Adhesive Properties ◽  
Distinctive Features ◽  
Experimental Part ◽  
Properties Of Materials ◽  
The Mathematical Model ◽  
Non Destructive

Classical methods of material testing become extremely complicated or impossible at micro-/nanoscale. At the same time, depth-sensing indentation (DSI) can be applied without much change at various length scales. However, interpretation of the DSI data needs to be done carefully, as length-scale dependent effects, such as adhesion, should be taken into account. This review paper is focused on different DSI approaches and factors that can lead to erroneous results, if conventional DSI methods are used for micro-/nanomechanical testing, or testing soft materials. We also review our recent advances in the development of a method that intrinsically takes adhesion effects in DSI into account: the Borodich–Galanov (BG) method, and its extended variant (eBG). The BG/eBG methods can be considered a framework made of the experimental part (DSI by means of spherical indenters), and the data processing part (data fitting based on the mathematical model of the experiment), with such distinctive features as intrinsic model-based account of adhesion, the ability to simultaneously estimate elastic and adhesive properties of materials, and non-destructive nature.

scholarly journals The use of flat-ended projectiles for determining dynamic yield stress - II. Tests on various metallic materials

1948 ◽  
Vol 194 (1038) ◽  
pp. 300-322 ◽  
Keyword(s):  
Yield Strength ◽  
Dynamic Strength ◽  
Soft Materials ◽  
Static Strength ◽  
Compressive Yield Strength ◽  
Dynamic Tests ◽  
Pure Lead ◽  
Permanent Strain ◽  
Yield Values ◽  
Static Conditions

A description is given of the experimental technique devised to apply the method outlined theoretically in part I to the measurement of the dynamic compressive yield strength of various steels, duralumin, copper, lead, iron and silver. A polished piece of armour steel was employed as a target, and cylindrical specimens were fired at it at various measured velocities from Service weapons. The distance between the weapon and target was made short to ensure normal impact, and apparatus was devised for the precise measurement of striking velocity over this short range. The dynamic compressive yield strength was computed from the density of the specimen, the striking velocity, and from measurements of the dimensions of the test piece before and after test. Details are given of the accuracy of the various measurements, and of their effect on the values of yield strength. The method was found to be inaccurate at low and high velocities. For instance, with mild steel, satisfactory results were only obtainable within the range 400 to 2500 ft. /sec. The range of velocities within which satisfactory results could be obtained varied with the quality of the material tested, soft metals giving results within a much lower range than that necessary for harder materials. Because of its failure at low velocities, the method could not be employed to bridge the gap between static and dynamic tests. The rate of strain employed in the dynamic tests could not be measured, but was estimated to be of the order of 10,000 in. /in. /sec. With the materials tested little change of dynamic strength occurred within the range of striking velocities employed, probably because the rate of strain did not vary to any great extent with the striking velocity. Within the range of weapons available, that is, from a 0·303 in. rifle up to a 13 pdr. gun (calibre 3·12 in.), little change of dynamic strength occurred with alteration of the initial dimensions of the specimens, probably because the corresponding change of rate of strain was not large. In general, the dynamic compressive yield strength S was greater than the static strength Y represented by the compressive stress giving 0·2% permanent strain. For steels of various types, regardless of chemical composition and heat treatment, there was a relation between S / Y and the static strength Y , the ratio decreasing from approximately 3 when Y was 20 tons/sq. in. to 1 when Y was 120 tons/sq. in. A similar relation occurred with duralumin, S / Y varying from 2·5 at Y = 8 tons/sq. in. to 1·4 at Y = 25 tons/sq. in. Dynamic compressive yield values were obtained for soft materials such as pure lead, copper and Armco iron, which, under static conditions, gave no definite yield values. A plot of the unstrained length of the specimen X , expressed as X / L (where L = initial overall length), versus the final overall length L 1 , expressed as L 1 / L , was made for the various materials. Any specified value of X / L was associated with greater values of L 1 / L for the more ductile materials, such as copper and lead, than for the brittle materials, such as armour plate and duralumin.

scholarly journals Un-jamming due to energetic instability: statics to dynamics

2021 ◽  
Vol 23 (4) ◽  
Author(s):  
Stefan Luding ◽  
Yimin Jiang ◽  
Mario Liu
Keyword(s):  
Granular Matter ◽  
Numerical Data ◽  
Soft Materials ◽  
Material Point ◽  
Solid States ◽  
Granular Gas ◽  
Granular Solid Hydrodynamics ◽  
Particle Simulations ◽  
Points Of View ◽  
Deformation Modes

Abstract Jamming/un-jamming, the transition between solid- and fluid-like behavior in granular matter, is an ubiquitous phenomenon in need of a sound understanding. As argued here, in addition to the usual un-jamming by vanishing pressure due to a decrease of density, there is also yield (plastic rearrangements and un-jamming that occur) if, e.g., for given pressure, the shear stress becomes too large. Similar to the van der Waals transition between vapor and water, or the critical current in superconductors, we believe that one mechanism causing yield is by the loss of the energy’s convexity (causing irreversible re-arrangements of the micro-structure, either locally or globally). We focus on this mechanism in the context of granular solid hydrodynamics (GSH), generalized for very soft materials, i.e., large elastic deformations, employing it in an over-simplified (bottom-up) fashion by setting as many parameters as possible to constant. Also, we complemented/completed GSH by using various insights/observations from particle simulations and calibrating some of the theoretical parameters—both continuum and particle points of view are reviewed in the context of the research developments during the last few years. Any other energy-based elastic-plastic theory that is properly calibrated (top-down), by experimental or numerical data, would describe granular solids. But only if it would cover granular gas, fluid, and solid states simultaneously (as GSH does) could it follow the system transitions and evolution through all states into un-jammed, possibly dynamic/collisional states—and back to elastically stable ones. We show how the un-jamming dynamics starts off, unfolds, develops, and ends. We follow the system through various deformation modes: transitions, yielding, un-jamming and jamming, both analytically and numerically and bring together the material point continuum model with particle simulations, quantitatively. Graphic abstract

Designing Chemically Selective Liquid Crystalline Materials that Respond to Oxidizing Gases

2021 ◽  
Author(s):  
Nanqi Bao ◽  
Jake Gold ◽  
Tibor Szilvasi ◽  
Huaizhe Yu ◽  
Robert Twieg ◽  
...  
Keyword(s):  
Computational Methods ◽  
First Principles ◽  
Liquid Crystalline ◽  
Soft Materials ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Chemically Selective ◽  
Kinetics Of

Computational methods can provide first-principles insights into the thermochemistry and kinetics of reactions at interfaces, but this capability has not been widely leveraged to design soft materials that respond selectively...

Soft materials for optical storage

2000 ◽  
Vol 23 (1) ◽  
pp. 1-28
Author(s):  
L. Lucchetti ◽  
F. Simoni
Keyword(s):  
Soft Materials ◽  
Optical Storage

scholarly journals Observing atomic resolution dynamics of soft materials with controlling dose rate

2021 ◽  
Vol 27 (S1) ◽  
pp. 2124-2126
Author(s):  
Fu-Rong Chen ◽  
Dirk Van Dyck ◽  
Christian Kisielowski ◽  
Stig Helveg
Keyword(s):  
Dose Rate ◽  
Soft Materials ◽  
Atomic Resolution

scholarly journals Polyelectrolyte Gels: A Unique Class of Soft Materials

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 102
Author(s):  
Ferenc Horkay
Keyword(s):  
Exchange Process ◽  
Interaction Strength ◽  
Soft Materials ◽  
Industrial Applications ◽  
Future Research ◽  
Swelling Kinetics ◽  
Polyelectrolyte Gels ◽  
Ion Exchange Process ◽  
Counter Ions ◽  
Kinetics Of

The objective of this article is to introduce the readers to the field of polyelectrolyte gels. These materials are common in living systems and have great importance in many biomedical and industrial applications. In the first part of this paper, we briefly review some characteristic properties of polymer gels with an emphasis on the unique features of this type of soft material. Unsolved problems and possible future research directions are highlighted. In the second part, we focus on the typical behavior of polyelectrolyte gels. Many biological materials (e.g., tissues) are charged (mainly anionic) polyelectrolyte gels. Examples are shown to illustrate the effect of counter-ions on the osmotic swelling behavior and the kinetics of the swelling of model polyelectrolyte gels. These systems exhibit a volume transition as the concentration of higher valence counter-ions is gradually increased in the equilibrium bath. A hierarchy is established in the interaction strength between the cations and charged polymer molecules according to the chemical group to which the ions belong. The swelling kinetics of sodium polyacrylate hydrogels is investigated in NaCl solutions and in solutions containing both NaCl and CaCl2. In the presence of higher valence counter-ions, the swelling/shrinking behavior of these gels is governed by the diffusion of free ions in the swollen network, the ion exchange process and the coexistence of swollen and collapsed states.

scholarly journals A numerical analysis of skin–PPE interaction to prevent facial tissue injury

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rikeen D. Jobanputra ◽  
Jack Hayes ◽  
Sravani Royyuru ◽  
Marc A. Masen
Keyword(s):  
Strain Energy Density ◽  
Strain Energy ◽  
Tissue Injury ◽  
Soft Materials ◽  
Element Model ◽  
Healthcare Systems ◽  
Skin Injury ◽  
Energy Density Distribution ◽  
The World ◽  
The Face

AbstractThe use of close-fitting PPE is essential to prevent exposure to dispersed airborne matter, including the COVID-19 virus. The current pandemic has increased pressure on healthcare systems around the world, leading to medical professionals using high-grade PPE for prolonged durations, resulting in device-induced skin injuries. This study focuses on computationally improving the interaction between skin and PPE to reduce the likelihood of discomfort and tissue damage. A finite element model is developed to simulate the movement of PPE against the face during day-to-day tasks. Due to limited available data on skin characteristics and how these vary interpersonally between sexes, races and ages, the main objective of this study was to establish the effects and trends that mask modifications have on the resulting subsurface strain energy density distribution in the skin. These modifications include the material, geometric and interfacial properties. Overall, the results show that skin injury can be reduced by using softer mask materials, whilst friction against the skin should be minimised, e.g. through use of micro-textures, humidity control and topical creams. Furthermore, the contact area between the mask and skin should be maximised, whilst the use of soft materials with incompressible behaviour (e.g. many elastomers) should be avoided.

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