A second gradient continuum model accounting for some effects of micro-structure on reconstructed bone remodelling

2012 ◽  
Vol 340 (8) ◽  
pp. 575-589 ◽  
Author(s):  
Angela Madeo ◽  
D. George ◽  
T. Lekszycki ◽  
Mathieu Nierenberger ◽  
Yves Rémond
Keyword(s):  
Continuum Model ◽  
Bone Remodelling ◽  
Micro Structure ◽  
Second Gradient ◽  
Second Gradient Continuum

Are higher-gradient models also capable of predicting mechanical behavior in the case of wide-knit pantographic structures?

2020 ◽  
Vol 26 (1) ◽  
pp. 18-29 ◽  
Author(s):  
Mario Spagnuolo ◽  
M Erden Yildizdag ◽  
Ugo Andreaus ◽  
Antonio M Cazzani
Keyword(s):  
Continuum Model ◽  
Central Theme ◽  
Fiber Density ◽  
Pantographic Structures ◽  
Numerical Predictions ◽  
Second Gradient ◽  
Bias Extension ◽  
Second Gradient Continuum ◽  
Gradient Models ◽  
Good Agreement

The central theme of this study is to investigate a remarkable capability of a second-gradient continuum model developed for pantographic structures. The model is applied to a particular type of this metamaterial, namely the wide-knit pantograph. As this type of structure has low fiber density, the applicability of such a continuum model may be questionable. To address this uncertainty, numerical simulations are conducted to analyze the behavior of a wide-knit pantographic structure, and the predicted results are compared with those measured experimentally under bias extension testing. The results presented in this study show that the numerical predictions and experimental measurements are in good agreement; therefore, in some useful circumstances, this model is applicable for the analysis of wide-knit pantographic structures.

scholarly journals Towards Recognition of Scale Effects in a Solid Model of Lattices with Tensegrity-Inspired Microstructure

Solids ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 50-59
Author(s):  
Wojciech Gilewski ◽  
Anna Al Sabouni-Zawadzka
Keyword(s):  
Mechanical Properties ◽  
Continuum Model ◽  
Scale Effects ◽  
Theory Of Elasticity ◽  
Solid Model ◽  
Gradient Theory ◽  
General Description ◽  
Normal Forces ◽  
Second Gradient ◽  
Proposed Model

This paper is dedicated to the extended solid (continuum) model of tensegrity structures or lattices. Tensegrity is defined as a pin-joined truss structure with an infinitesimal mechanism stabilized by a set of self-equilibrated normal forces. The proposed model is inspired by the continuum model that matches the first gradient theory of elasticity. The extension leads to the second- or higher-order gradient formulation. General description is supplemented with examples in 2D and 3D spaces. A detailed form of material coefficients related to the first and second deformation gradients is presented. Substitute mechanical properties of the lattice are dependent on the cable-to-strut stiffness ratio and self-stress. Scale effect as well as coupling of the first and second gradient terms are identified. The extended solid model can be used for the evaluation of unusual mechanical properties of tensegrity lattices.

scholarly journals Bias extension test on an unbalanced woven composite reinforcement: Experiments and modeling via a second-gradient continuum approach

2016 ◽  
Vol 51 (2) ◽  
pp. 153-170 ◽  
Author(s):  
Gabriele Barbagallo ◽  
Angela Madeo ◽  
Ismael Azehaf ◽  
Ivan Giorgio ◽  
Fabrice Morestin ◽  
...  
Keyword(s):  
Constitutive Expression ◽  
Woven Fabrics ◽  
Woven Composite ◽  
Plane Shear ◽  
Second Gradient ◽  
Proposed Model ◽  
Bias Extension Test ◽  
Bias Extension ◽  
Deformation Patterns ◽  
Second Gradient Continuum

The classical continuum models used for the woven fabrics do not fully describe the whole set of phenomena that occur during the testing of those materials. This incompleteness is partially due to the absence of energy terms related to some microstructural properties of the fabric and, in particular, to the bending stiffness of the yarns. To account for the most fundamental microstructure-related deformation mechanisms occurring in unbalanced interlocks, a second-gradient, hyperelastic, initially orthotropic continuum model is proposed. A constitutive expression for the strain energy density is introduced to account for (a) in-plane shear deformations, (b) highly different bending stiffnesses in the warp and weft directions, and (c) fictive elongations in the warp and weft directions which eventually describe the relative sliding of the yarns. Numerical simulations which are able to reproduce the experimental behavior of unbalanced carbon interlocks subjected to a bias extension test are presented. In particular, the proposed model captures the macroscopic asymmetric S-shaped deformation of the specimen, as well as the main features of the associated deformation patterns of the yarns at the mesoscopic scale.

Construction of second gradient continuum models for random fibrous networks and analysis of size effects

2017 ◽  
Vol 181 ◽  
pp. 347-357 ◽  
Author(s):  
K. Berkache ◽  
S. Deogekar ◽  
I. Goda ◽  
R.C. Picu ◽  
J.-F. Ganghoffer
Keyword(s):  
Size Effects ◽  
Continuum Models ◽  
Second Gradient ◽  
Second Gradient Continuum

Continuum model of microstructure induced softening for strain gradient materials

2018 ◽  
Vol 24 (8) ◽  
pp. 2374-2391 ◽  
Author(s):  
Massimo Cuomo
Keyword(s):  
Continuum Model ◽  
Large Scale ◽  
Scale Effects ◽  
Gradient Material ◽  
Complex Materials ◽  
Gradient Plasticity ◽  
Gradient Materials ◽  
Second Gradient ◽  
Evolution Laws ◽  
Anelastic Deformation

Gradient plasticity has been introduced to predict localization bands induced by softening or damage, and has been extended to micromorphic models used for materials with microstructure and scale effects. Motivated by the consideration that in complex materials there may exist different mechanisms for the evolution of anelastic deformation at the small and at the large scale, and that they may interact, in the paper a model of second gradient material with two different evolution laws for the macroscopic and for the microscopic plastic strain is proposed, the latter related to the presence of second gradient deformation. The model is intended to be used for metamaterials, and its relevant properties can be obtained from an homogenization analysis at the microlevel.

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