Differentiating between remote and local strain fields near mesoscale faults by magnetic fabrics in deformed chalks

2022 ◽  
pp. 104524
Author(s):  
R. Issachar ◽  
T. Levi ◽  
R. Weinberger
Keyword(s):  
Local Strain ◽  
Strain Fields ◽  
Magnetic Fabrics

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.

New bounds on local strain fields inside random heterogeneous materials

2012 ◽  
Vol 53 ◽  
pp. 111-122 ◽  
Author(s):  
Bacim Alali ◽  
Robert Lipton
Keyword(s):  
Heterogeneous Materials ◽  
Local Strain ◽  
Strain Fields

Investigation of local strain fields during high-speed deformation

1997 ◽  
Vol 9 (1-2) ◽  
pp. 207-217 ◽  
Author(s):  
J. Trötzschel ◽  
S. Müller ◽  
W. Pantleon ◽  
P. Klimanek
Keyword(s):  
High Speed ◽  
Local Strain ◽  
Strain Fields ◽  
High Speed Deformation

scholarly journals Multipoint Approximation of Statistical Descriptors of Local Strain and Stress Fields in Heterogeneous Media Using Integral Equation Method

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Mikhail Tashkinov
Keyword(s):  
Correlation Functions ◽  
Heterogeneous Media ◽  
Boundary Value ◽  
Local Strain ◽  
Statistical Characteristics ◽  
Stress And Strain ◽  
Strain Fields ◽  
Representative Volume ◽  
Multipoint Approximation ◽  
Analytical Expressions

This paper is devoted to derivation of analytic expressions for statistical descriptors of stress and strain fields in heterogeneous media. Multipoint approximations of solutions of stochastic elastic boundary value problems for representative volume elements are investigated. The stress and strain fields are represented in the form of random coordinate functions, for which analytical expressions for the first- and second-order statistical central moments are obtained. Such moments characterize distribution of fields under prescribed loading of a representative volume element and depend on the geometry features and location of components within a volume. The information of the internal geometrical structure is taken into account by means of multipoint correlation functions. Within the framework of the second approximation of the boundary value problem, the correlation functions up to the fifth order are required to calculate the statistical characteristics. Using the method of Green’s functions, analytical expressions for the moments in distinct phases of the microstructure are obtained explicitly in a form of integral equations. Their analysis and comparison with previously obtained results are performed.

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.

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