scholarly journals Verifying Larché–Cahn elasticity, a milestone of 20th-century thermodynamics

2018 ◽  
Vol 115 (43) ◽  
pp. 10914-10919 ◽  
Author(s):  
Shan Shi ◽  
Jürgen Markmann ◽  
Jörg Weissmüller
Keyword(s):  
20Th Century ◽  
Open System ◽  
Solid Mechanics ◽  
Chemical Potential ◽  
Local Strain ◽  
Elastic Parameters ◽  
Dynamic Mechanical Analyzer ◽  
Strain Gradients ◽  
Alloy Chemistry ◽  
Diffusion Paths

Many materials phenomena are governed by the interaction between chemistry and mechanics. However, it was only in the second half of the 20th century that the theory of open system elasticity by Francis Larché and John W. Cahn concatenated the fields of solid mechanics and alloy chemistry. As the theory’s central materials descriptors, the open system elastic parameters describe how solids deform under stress when solute can rearrange at equilibrium while the chemical potential is held constant. Here, we report experiments verifying the predictions for these parameters. We study the elasticity of nanoporous Pd-H and Pd-Au-H during load cycles imposed by a dynamic mechanical analyzer. Short diffusion paths afford fast equilibration of H in the local strain gradients that carry the macroscopic elastic deformation. The experiment is in excellent agreement with the theory, confirming a central prediction of one of the key contributions to 20th-century thermodynamics.

scholarly journals Time dependence of cellular responses to dynamic and complex strain fields

2019 ◽  
Vol 11 (1) ◽  
pp. 4-15 ◽  
Author(s):  
Sophie Chagnon-Lessard ◽  
Michel Godin ◽  
Andrew E Pelling
Keyword(s):  
Strain Gradient ◽  
Strain Field ◽  
Local Strain ◽  
Cellular Responses ◽  
Strain Fields ◽  
Strain Gradients ◽  
Biologically Relevant ◽  
Physical Cues ◽  
History Of ◽  
Strain Direction

Abstract Exposing cells to an unconventional sequence of physical cues can reveal subtleties of cellular sensing and response mechanisms. We investigated the mechanoresponse of cyclically stretched fibroblasts under a spatially non-uniform strain field which was subjected to repeated changes in stretching directions over 55 h. A polydimethylsiloxane microfluidic stretcher array optimized for complex staining procedures and imaging was developed to generate biologically relevant strain and strain gradient amplitudes. We demonstrated that cells can successfully reorient themselves repeatedly, as the main cyclical stretching direction is consecutively switched between two perpendicular directions every 11 h. Importantly, from one reorientation to the next, the extent to which cells reorient themselves perpendicularly to the local strain direction progressively decreases, while their tendency to align perpendicularly to the strain gradient direction increases. We demonstrate that these results are consistent with our finding that cellular responses to strains and strain gradients occur on two distinct time scales, the latter being slower. Overall, our results reveal the absence of major irreversible cellular changes that compromise the ability to sense and reorient to changing strain directions under the conditions of this experiment. On the other hand, we show how the history of strain field dynamics can influence the cellular realignment behavior, due to the interplay of complex time-dependent responses.

Elastic relaxation and correlation of local strain gradients with ferroelectric domains in (001) BiFeO3 nanostructures

2011 ◽  
Vol 99 (5) ◽  
pp. 052902 ◽  
Author(s):  
Jeffrey A. Klug ◽  
Martin V. Holt ◽  
Ramesh Nath Premnath ◽  
Alexandra Joshi-Imre ◽  
Seungbum Hong ◽  
...  
Keyword(s):  
Local Strain ◽  
Strain Gradients ◽  
Ferroelectric Domains

scholarly journals ABOUT ONE MODEL OF THE CLAY SHALE SWELLING AROUND THE CYLINDRICAL WELLBORE

2019 ◽  
Vol 4 (1) ◽  
pp. 172-179
Author(s):  
Bunyod Imomnazarov ◽  
Vadim Nyago ◽  
Ilkhom Khaydarov
Keyword(s):  
Plane Strain ◽  
Linear Theory ◽  
Chemical Potential ◽  
Aqueous Electrolyte ◽  
Total Stress ◽  
Elastic Parameters ◽  
Clay Shale

This paper proposes a modified version of the linear theory of poroelasticity, described by the three elastic parameters applied to the shale swelling with aqueous electrolyte. It is assumed that the shale behaves as an isotropic, ideal ionic membrane, and in this case the swelling depends only on the total stress and on the chemical potential of water in the pores of the rock. An analysis of the plane strain around the wellbore has been made.

scholarly journals Stability analysis of a nanopatterned bimaterial interface

2021 ◽  
Vol 17 (1) ◽  
pp. 97-104
Author(s):  
Gleb M. Shuvalov ◽  
◽  
Sergey A. Kostyrko ◽  
Keyword(s):  
Solid Mechanics ◽  
Chemical Potential ◽  
Plane Elasticity ◽  
Interface Roughness ◽  
Bimaterial Interface ◽  
Bulk Materials ◽  
Atom Flux ◽  
Interface Elasticity ◽  
Curved Interface ◽  
Plane Elasticity Problem

In the article it is shown that the nanopatterned interface of bimaterial is unstable due to the diffusion atom flux along the interface. The main goal of the research is to analyze the conditions of interface stability. The authors developed a model coupling thermodynamics and solid mechanics frameworks. In accordance with the Gurtin—Murdoch theory of surface/interface elasticity, the interphase between two materials is considered as a negligibly thin layer with the elastic properties differing from those of the bulk materials. The growth rate of interface roughness depends on the variation of the chemical potential at the curved interface, which is a function of interface and bulk stresses. The stress distribution along the interface is found from the solution of plane elasticity problem taking into account plane strain conditions. Following this, the linearized evolution equation is derived, which describes the amplitude change of interface perturbation with time.

Heterogeneous and Open Systems

1993 ◽  
Author(s):  
Greg M. Anderson ◽  
David A. Crerar
Keyword(s):  
Open System ◽  
Chemical Potential ◽  
Open Systems ◽  
The Other ◽  
Phase Rule ◽  
Clear Cut ◽  
Experimental Systems ◽  
Fixed Composition ◽  
Closed Systems ◽  
The Difference

Up to this point, with minor exceptions, we have discussed only closed systems, that is, systems having a fixed composition, and have for the most part not bothered to consider whether the system was homogeneous (one phase) or heterogeneous (more than one phase). We must now explicitly consider the implications of having more than one phase, and of the transfer of matter between phases and into and out of the system. There are two kinds of open systems that concern us, illustrated in Figure 14.1. In the first kind, the open system is simply a separate phase in a system that is closed overall, illustrated in Figure 14.la. The phases are free to change composition by exchange of components in response to changes in the conditions (say P and T) of the closed system. The phases in a crystallizing magrna are examples of open systems in this sense. In the second kind we distinguish the system from an environment, joined by means of a membrane permeable only to certain components (Figure 14. Ib). This enables the system to change composition in response to conditions in the environment, which may be quite different from those in the system. The membrane may be real, as in the case of experimental systems in which hydrogen, having an externally controlled fugacity, diffuses into the system through the platinum walls of the system, or it may be imaginary, as when it is used to help clarify our thinking about metasomatic processes. Of course, if you think carefully about it, the difference between the two cases is not always very clear-cut. For example in the crystallizing magma, quartz and the melt in which it is crystallizing could be considered as the "environment" for the other crystallizing phases, controlling their chemical potential of SiO2. Nevertheless, the distinction is usually clear enough for our purposes. We will first consider open systems in the first sense in the derivation of the phase rule, and then consider cases of "membrane" or "osmotic" equilibria, which is the kind that the term "open system" has generally come to mean in geochemistry.

scholarly journals Time dependence of cellular responses to dynamic and complex strain fields

2018 ◽  
Author(s):  
Sophie Chagnon-Lessard ◽  
Michel Godin ◽  
Andrew E. Pelling
Keyword(s):  
Strain Field ◽  
Local Strain ◽  
Cellular Responses ◽  
Time Dependent ◽  
Strain Fields ◽  
Strain Gradients ◽  
Biologically Relevant ◽  
Physical Cues ◽  
History Of ◽  
Strain Direction

ABSTRACTExposing cells to an unconventional sequence of physical cues can reveal subtleties of cellular sensing and response mechanisms. We investigated the mechanoresponse of cyclically-stretched fibroblasts under a spatially non-uniform strain field which was subjected to repeated changes in stretching directions over 55 hours. A polydimethylsiloxane microfluidic stretcher array optimized for complex staining procedures and imaging was developed to generate biologically relevant strain and strain gradient amplitudes. We demonstrated that cells can successfully reorient themselves repeatedly, as the main cyclical stretching direction is consecutively switched between two perpendicular directions every 11 hours. Importantly, from one reorientation to the next, the extent to which cells reorient themselves perpendicularly to the local strain direction progressively decreases, while their tendency to align perpendicularly to the strain gradient direction tends to increase. We demonstrate that these results are consistent with our finding that cellular responses to strains and strain gradients occur on two distinct time scales, the latter being slower. Overall, our results reveal the absence of major irreversible cellular changes that compromise the ability to sense and reorient to changing strain directions under the conditions of this experiment. On the other hand, we show how the history of strain field dynamics can influence the cellular realignment behavior, due to the interplay of complex time-dependent responses.

Structural Imperfections in thin Oxide Films Formed on Some Fe- and Ni-Base Alloys

1970 ◽  
Vol 28 ◽  
pp. 510-511
Author(s):  
L. P. Lemaire ◽  
D. E. Fornwalt ◽  
F. S. Pettit ◽  
B. H. Kear
Keyword(s):  
Oxide Scale ◽  
Oxidation Process ◽  
Short Circuit ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Thin Oxide Films ◽  
Diffusion Paths ◽  
Oxidation Resistant ◽  
Structural Imperfections ◽  
Short Circuit Diffusion

Oxidation resistant alloys depend on the formation of a continuous layer of protective oxide scale during the oxidation process. The initial stages of oxidation of multi-component alloys can be quite complex, since numerous metal oxides can be formed. For oxidation resistance, the composition is adjusted so that selective oxidation occurs of that element whose oxide affords the most protection. Ideally, the protective oxide scale should be i) structurally perfect, so as to avoid short-circuit diffusion paths, and ii) strongly adherent to the alloy substrate, which minimizes spalling in response to thermal cycling. Small concentrations (∼ 0.1%) of certain reactive elements, such as yttrium, markedly improve the adherence of oxide scales in many alloy systems.

Quantitative analysis of in situ straining experiments in the case of strong frictional forces

1978 ◽  
Vol 36 (1) ◽  
pp. 570-571
Author(s):  
F. Louchet ◽  
L.P. Kubin
Keyword(s):  
Strain Rate ◽  
Radiation Effects ◽  
Dislocation Line ◽  
Critical Length ◽  
Local Strain ◽  
Local Flow ◽  
Double Kink ◽  
Dislocation Densities ◽  
Frictional Forces ◽  
Local Strain Rate

Investigation of frictional forces -Experimental techniques and working conditions in the high voltage electron microscope have already been described (1). Care has been taken in order to minimize both surface and radiation effects under deformation conditions.Dislocation densities and velocities are measured on the records of the deformation. It can be noticed that mobile dislocation densities can be far below the total dislocation density in the operative system. The local strain-rate can be deduced from these measurements. The local flow stresses are deduced from the curvature radii of the dislocations when the local strain-rate reaches the values of ∿ 10-4 s-1.For a straight screw segment of length L moving by double-kink nucleation between two pinning points, the velocity is :where ΔG(τ) is the activation energy and lc the critical length for double-kink nucleation. The term L/lc takes into account the number of simultaneous attempts for double-kink nucleation on the dislocation line.

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