Bending of marble with intrinsic length scales : A gradient theory with surface energy and size effects

1998 ◽  
Vol 08 (PR8) ◽  
pp. Pr8-399-Pr8-406 ◽  
Author(s):  
I. Vardoulakis ◽  
G. Exadaktylos ◽  
S. K. Kourkoulis
Keyword(s):  
Surface Energy ◽  
Size Effects ◽  
Gradient Theory ◽  
Length Scales ◽  
Intrinsic Length

Material Intrinsic Length in Plastic Strain Gradient Theory and Microbending Process of Metal Foils

2011 ◽  
Vol 403-408 ◽  
pp. 685-690
Author(s):  
He Zong Li ◽  
Xiang Huai Dong ◽  
Su Xia Huang ◽  
Alexander Diehl ◽  
Hinnerk Hagenah
Keyword(s):  
Plastic Strain ◽  
Strain Gradient ◽  
Size Effects ◽  
Bending Moment ◽  
Strain Gradient Theory ◽  
Foil Thickness ◽  
Gradient Theory ◽  
Metal Foils ◽  
Intrinsic Length ◽  
Plastic Strain Gradient

In microbending experiments of metal foils an increase of non-dimensional bending moment with decreasing foil thickness has been observed, which indicates the obvious presence of size effects. It is attributed to plastic strain gradient. So a constitutive model taking into account plastic strain gradient together with conventional plastic strain hardening is proposed to analyze the non-dimensional bending moment in microbending process. It is confirmed that the predictions by using the proposed hardening model agree well with the experimental data, while those determined by using conventional elastoplastic model cannot capture such size effects. A semi-empirical expression is reasonable to determine the material intrinsic length as a function of shear modulus, initial yield strength, length of Burger’s vector, grain size, and macro geometrical characteristic scale of the specimen.

Modeling of Size Effects on the Flow Stress of Type 304 Stainless Steel and Application in Coining Process

2007 ◽  
Author(s):  
Gap-Yong Kim ◽  
Muammer Koc ◽  
Jun Ni
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Flow Stress ◽  
Size Effect ◽  
Size Effects ◽  
Specimen Size ◽  
304 Stainless Steel ◽  
Length Scales ◽  
Type 304 ◽  
Type 304 Stainless Steel

Application of microforming in various research areas has received much attention due to the increased demand for miniature metallic parts that require mass production. For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/meso-scale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the “feature/specimen size” effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with experiments obtained from previous research and showed a very good agreement. The model was also applied to forming of micro-features by coining. A flow stress model for Type 304 stainless steel taking into consideration the effect of the grain and feature size was developed and implemented into a finite element simulation tool for an accurate numerical analysis. The scaling model offered a simple way to model the size effect down to length scales of a couple of grains and extended the use of continuum plasticity theories to micro/meso-length scales.

Flow transitions and length scales of a channel-confined active nematic

Soft Matter ◽  
2021 ◽  
Author(s):  
Abhik Samui ◽  
Julia M. Yeomans ◽  
Sumesh P. Thampi
Keyword(s):  
Characteristic Length ◽  
Flow Regimes ◽  
Channel Width ◽  
Flow Structures ◽  
Length Scale ◽  
Length Scales ◽  
Turbulence Regime ◽  
Active Turbulence ◽  
Intrinsic Length ◽  
Flow Transitions

Different flow regimes realised by a channel-confined active nematic have a characteristic length same as channel width. Flow structures exhibit the intrinsic length scale of the fluid only in the fully developed active turbulence regime.

scholarly journals Three-dimensional numerical simulation of soft-tissue wound healing using constrained-mixture anisotropic hyperelasticity and gradient-enhanced damage mechanics

2020 ◽  
Vol 17 (162) ◽  
pp. 20190708 ◽  
Author(s):  
Di Zuo ◽  
Stéphane Avril ◽  
Haitian Yang ◽  
S. Jamaleddin Mousavi ◽  
Klaus Hackl ◽  
...  
Keyword(s):  
Wound Healing ◽  
Damage Mechanics ◽  
Healing Process ◽  
Three Dimensional ◽  
Biological Tissues ◽  
Collagen Fibres ◽  
Length Scales ◽  
Constrained Mixture ◽  
Proposed Model ◽  
Intrinsic Length

Healing of soft biological tissues is the process of self-recovery or self-repair after injury or damage to the extracellular matrix (ECM). In this work, we assume that healing is a stress-driven process, which works at recovering a homeostatic stress metric in the tissue by replacing the damaged ECM with a new undamaged one. For that, a gradient-enhanced continuum healing model is developed for three-dimensional anisotropic tissues using the modified anisotropic Holzapfel–Gasser–Ogden constitutive model. An adaptive stress-driven approach is proposed for the deposition of new collagen fibres during healing with orientations assigned depending on the principal stress direction. The intrinsic length scales of soft tissues are considered through the gradient-enhanced term, and growth and remodelling are simulated by a constrained-mixture model with temporal homogenization. The proposed model is implemented in the finite-element package Abaqus by means of a user subroutine UEL. Three numerical examples have been achieved to illustrate the performance of the proposed model in simulating the healing process with various damage situations, converging towards stress homeostasis. The orientations of newly deposited collagen fibres and the sensitivity to intrinsic length scales are studied through these examples, showing that both have a significant impact on temporal evolutions of the stress distribution and on the size of the damage region. Applications of the approach to carry out in silico experiments of wound healing are promising and show good agreement with existing experiment results.

Orientation dependent size effects in single crystalline anisotropic nanoplates with regard to surface energy

2015 ◽  
Vol 379 (22-23) ◽  
pp. 1437-1444 ◽  
Author(s):  
Abbas Assadi ◽  
Manouchehr Salehi ◽  
Mehdi Akhlaghi
Keyword(s):  
Surface Energy ◽  
Size Effects ◽  
Single Crystalline

Length Scale Dependent Deformation in Polymers

2012 ◽  
Author(s):  
F. Alisafaei ◽  
Seyed Hamid Reza Sanei ◽  
Chung-Souk Han
Keyword(s):  
Liquid Crystal ◽  
Size Effects ◽  
Liquid Crystal Polymers ◽  
Length Scale ◽  
Indentation Testing ◽  
Indentation Size ◽  
Length Scales ◽  
Indentation Tests ◽  
Length Scale Dependent Deformation ◽  
Beam Bending

Length scale dependent deformation of polymers has been observed in different experiments including micro-beam bending and indentation tests. Here the length scale dependent deformation of polydimethylsiloxane is examined in indentation testing at length scales from microns down to hundreds of nanometers. Strong indentation size effects have been observed in these experiments which are rationalized with rotation gradients that can be related to Frank elasticity type molecular energies known from liquid crystal polymers. To support this notion additional experiments have been conducted where Berkovich and spherical indenter tips results have been compared with each other.

Sign in / Sign up

Export Citation Format

Share Document