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.

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.

Strain Gradient Effect in Cone Indentation

2002 ◽  
Vol 741 ◽  
Author(s):  
Anthony A. DiCarlo ◽  
Henry T. Y. Yang ◽  
Srinivasan Chandrasekar
Keyword(s):  
Strain Gradient ◽  
Indentation Size ◽  
Strain Fields ◽  
Strain Gradients ◽  
Element Simulation ◽  
Macro Scale ◽  
Self Similar ◽  
Rotational Strain ◽  
Indentation Strain

ABSTRACTA size effect is known to exist in the strength and hardness of metals at small length scales. For example, the hardness of a pyramid indentation at the macro-scale is constant and typically independent of indentation size due to the self-similar feature of the indentation. But, at the meso-scale, this hardness has been observed to increase with decreasing indentation size. This increase has been attributed to the influence of strain gradient on the flow stress. At this point, the contribution of a rotational gradient to the hardness is unclear.This study investigates the sensitivity of the hardness to rotational strain gradients through a Cosserat continuum. Finite element simulation of cone indentation is employed to conduct this investigation. The effect of varying indentation strain fields is modeled using indentation with cones of varying angles. The results demonstrate the role of rotational gradients in indentation.

Strain analysis with nanometer resolution using a conventional transmission electron microsopy technique: electron diffraction contrast imaging revisited

1995 ◽  
Vol 53 ◽  
pp. 168-169
Author(s):  
Koenraad G F Janssens ◽  
Omer Van der Biest ◽  
Jan Vanhellemont ◽  
Herman E Maes ◽  
Robert Hull
Keyword(s):  
Electron Diffraction ◽  
Strain Field ◽  
Elastic Strain ◽  
Strain Analysis ◽  
Local Strain ◽  
Contrast Imaging ◽  
Strain Characterization ◽  
Physical Mechanisms ◽  
Diffraction Contrast ◽  
Transmission Electron

There is a growing need for elastic strain characterization techniques with submicrometer resolution in several engineering technologies. In advanced material science and engineering the quantitative knowledge of elastic strain, e.g. at small particles or fibers in reinforced composite materials, can lead to a better understanding of the underlying physical mechanisms and thus to an optimization of material production processes. In advanced semiconductor processing and technology, the current size of micro-electronic devices requires an increasing effort in the analysis and characterization of localized strain. More than 30 years have passed since electron diffraction contrast imaging (EDCI) was used for the first time to analyse the local strain field in and around small coherent precipitates1. In later stages the same technique was used to identify straight dislocations by simulating the EDCI contrast resulting from the strain field of a dislocation and comparing it with experimental observations. Since then the technique was developed further by a small number of researchers, most of whom programmed their own dedicated algorithms to solve the problem of EDCI image simulation for the particular problem they were studying at the time.

Delamination in the scoring and folding of paperboard

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 61-66 ◽  
Author(s):  
DOEUNG D. CHOI ◽  
SERGIY A. LAVRYKOV ◽  
BANDARU V. RAMARAO
Keyword(s):  
Finite Element ◽  
Plane Deformation ◽  
Strain Analysis ◽  
Local Strain ◽  
Uniaxial Stress ◽  
Material Model ◽  
Element Model ◽  
Plastic Behavior ◽  
Stress Strain ◽  
Strain Fields

Delamination between layers occurs during the creasing and subsequent folding of paperboard. Delamination is necessary to provide some stiffness properties, but excessive or uncontrolled delamination can weaken the fold, and therefore needs to be controlled. An understanding of the mechanics of delamination is predicated upon the availability of reliable and properly calibrated simulation tools to predict experimental observations. This paper describes a finite element simulation of paper mechanics applied to the scoring and folding of multi-ply carton board. Our goal was to provide an understanding of the mechanics of these operations and the proper models of elastic and plastic behavior of the material that enable us to simulate the deformation and delamination behavior. Our material model accounted for plasticity and sheet anisotropy in the in-plane and z-direction (ZD) dimensions. We used different ZD stress-strain curves during loading and unloading. Material parameters for in-plane deformation were obtained by fitting uniaxial stress-strain data to Ramberg-Osgood plasticity models and the ZD deformation was modeled using a modified power law. Two-dimensional strain fields resulting from loading board typical of a scoring operation were calculated. The strain field was symmetric in the initial stages, but increasing deformation led to asymmetry and heterogeneity. These regions were precursors to delamination and failure. Delamination of the layers occurred in regions of significant shear strain and resulted primarily from the development of large plastic strains. The model predictions were confirmed by experimental observation of the local strain fields using visual microscopy and linear image strain analysis. The finite element model predicted sheet delamination matching the patterns and effects that were observed in experiments.

The Mechanical Behavior of Aluminium Alloy Quenching Process

2011 ◽  
Vol 228-229 ◽  
pp. 822-827
Author(s):  
Jia Yuan Luo ◽  
Rong Fan ◽  
Cheng Xiang Shi
Keyword(s):  
Surface Layer ◽  
Aluminum Alloy ◽  
Dynamic Simulation ◽  
Strain Field ◽  
Method Development ◽  
Experimental Tests ◽  
Analysis Method ◽  
Process Dynamic ◽  
Quenching Process ◽  
History Of

Since the aluminum alloy quenching is a complicated and a prompt heat-pressure coupling processing, traditional experimental tests and empirical judgments cannot explain and predict the physical and the force behavior completely during the quenching process. Dynamic simulation of the quenching process is conducted using the finite analysis method. Development laws of the stress and the strain field of the surface layer and core of the alloy during the quenching process are described based on the verification of the simulation. States and process history of the stress and the strain in each phase during the quench are obtained, which provides ponderable data and theoretical value for a fully understanding of the aluminum alloy quenching.

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.

Damage Observation and Analysis of a Rock Brazilian Disc Using High-Speed DIC Method

2011 ◽  
Vol 70 ◽  
pp. 87-92 ◽  
Author(s):  
Shao Peng Ma ◽  
Dong Yan ◽  
Xian Wang ◽  
Yan Yan Cao
Keyword(s):  
Strain Field ◽  
Damage Evolution ◽  
High Speed ◽  
Failure Process ◽  
Tensile Load ◽  
Brazilian Test ◽  
Elastic Model ◽  
Strain Fields ◽  
Brazilian Disc ◽  
Damage And Failure

Observation of damage evolution is of great importance to the understanding of the failure process of rock materials. High-speed DIC system is constructed and used to observe the strain field evolution of the granodiorite disc in Brazilian test. The strain fields at different load levels are analyzed based on the stain abnormality indicator (SAI) which is the ratio of the strain measured in experiment to the strain from theoretical solution in an isotropy and elastic model. SAI could be used to indicate the damage in the specimen. The process of damage and failure of the specimen in Brazilian disc test is quantitatively analyzed and deeply discussed according to the strain fields and the statistics of SAI. Experimental results in this paper show that the failure process of the disc specimen in Brazilian test is not simple crack propagation under tensile load, but a complicated damage evolution procedure.

scholarly journals Cellular orientation is guided by strain gradients

2017 ◽  
Vol 9 (7) ◽  
pp. 607-618 ◽  
Author(s):  
Sophie Chagnon-Lessard ◽  
Hubert Jean-Ruel ◽  
Michel Godin ◽  
Andrew E. Pelling
Keyword(s):  
Long Range ◽  
Strain Gradients ◽  
Physical Cues

A biomimetic microdevice reveals that strain gradients act as potent physical cues which guide the long-range organization of cells.

scholarly journals Inversion of higher order isotropic tensors with minor symmetries and solution of higher order heterogeneity problems

2010 ◽  
Vol 467 (2126) ◽  
pp. 314-332 ◽  
Author(s):  
Vincent Monchiet ◽  
Guy Bonnet
Keyword(s):  
Closed Form ◽  
Strain Field ◽  
Spherical Inclusion ◽  
Higher Order ◽  
Quadratic Polynomial ◽  
Elastic Matrix ◽  
Closed Form Expression ◽  
Form Expression ◽  
Order Tensor ◽  
Strain Fields

In this paper, the derivation of irreducible bases for a class of isotropic 2 n th-order tensors having particular ‘minor symmetries’ is presented. The methodology used for obtaining these bases consists of extending the concept of deviatoric and spherical parts, commonly used for second-order tensors, to the case of an n th-order tensor. It is shown that these bases are useful for effecting the classical tensorial operations and especially the inversion of a 2 n th-order tensor. Finally, the formalism introduced in this study is applied for obtaining the closed-form expression of the strain field within a spherical inclusion embedded in an infinite elastic matrix and subjected to linear or quadratic polynomial remote strain fields.

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