scholarly journals Minimization of Shear Energy in Two Dimensional Continua with Two Orthogonal Families of Inextensible Fibers: The Case of Standard Bias Extension Test

2015 ◽  
Vol 122 (2) ◽  
pp. 131-155 ◽  
Author(s):  
F. dell’Isola ◽  
M. V. d’Agostino ◽  
A. Madeo ◽  
P. Boisse ◽  
D. Steigmann
Keyword(s):  
Two Dimensional ◽  
Bias Extension Test ◽  
Bias Extension ◽  
Inextensible Fibers ◽  
Shear Energy

scholarly journals Variational modelling of nematic elastomer foundations

2018 ◽  
Vol 28 (14) ◽  
pp. 2863-2904
Author(s):  
Pierluigi Cesana ◽  
Andrés A. León Baldelli
Keyword(s):  
Liquid Crystal ◽  
Integral Functional ◽  
Elastic Membrane ◽  
Two Dimensional ◽  
Order Tensor ◽  
Asymptotic Regime ◽  
Liquid Crystal Elastomer ◽  
Energy Functionals ◽  
Shear Energy ◽  
Dimensional Integral

We compute the [Formula: see text]-limit of energy functionals describing mechanical systems composed of a thin nematic liquid crystal elastomer sustaining a homogeneous and isotropic elastic membrane. We work in the regime of infinitesimal displacements and model the orientation of the liquid crystal according to the order tensor theories of both Frank and De Gennes. We describe the asymptotic regime by analysing a family of functionals parametrised by the vanishing thickness of the membranes and the ratio of the elastic constants, establishing that, in the limit, the system is represented by a two-dimensional integral functional interpreted as a linear membrane on top of a nematic active foundation involving an effective De Gennes optic tensor which allows for low order states. The latter can suppress shear energy by formation of microstructure as well as act as a pre-strain transmitted by the foundation to the overlying film.

scholarly journals Modelling the Shear-Tension Coupling of Woven Engineering Fabrics

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
F. Abdiwi ◽  
P. Harrison ◽  
W. R. Yu
Keyword(s):  
Finite Element ◽  
Iterative Process ◽  
Selection Process ◽  
Simple Algorithm ◽  
Model Parameters ◽  
Multiple Input ◽  
Bias Extension Test ◽  
Current Value ◽  
Bias Extension ◽  
Shear Compliance

An approach to incorporate the coupling between the shear compliance and in-plane tension of woven engineering fabrics, in finite-element-based numerical simulations, is described. The method involves the use of multiple input curves that are selectively fed into a hypoelastic constitutive model that has been developed previously for engineering fabrics. The selection process is controlled by the current value of the in-plane strain along the two fibre directions using a simple algorithm. Model parameters are determined from actual experimental data, measured using the Biaxial Bias Extension test. An iterative process involving finite element simulations of the experimental test is used to normalise the test data for use in the code. Finally, the effectiveness of the method is evaluated and shown to provide qualitatively good predictions.

Large Deformation and Failure Mechanism of Plain Woven Composite in Bias Extension Test

2007 ◽  
Vol 334-335 ◽  
pp. 253-256 ◽  
Author(s):  
B. Zhu ◽  
T.X. Yu ◽  
Xiao Ming Tao
Keyword(s):  
Large Deformation ◽  
Failure Mechanism ◽  
Point Of View ◽  
Image Correlation ◽  
Subsequent Paper ◽  
Woven Composite ◽  
Deformation And Failure ◽  
Bias Extension Test ◽  
Bias Extension ◽  
Digital Image Correlation Analysis

Large shear deformation of plain woven composite sheets and corresponding failure mechanism are investigated by bias extension test. Digital image correlation analysis was conducted on a series of photos taken during the test. Four typical phases were identified, and a theoretical model of the large deformation is proposed from energy point of view. Numerical simulations have also been carried out, but it will be reported in a subsequent paper.

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.

An Integral Mesoscopic Material Characterization Approach

2014 ◽  
Vol 611-612 ◽  
pp. 280-291 ◽  
Author(s):  
Frank Härtel ◽  
Patrick Böhler ◽  
Peter Middendorf
Keyword(s):  
Forming Process ◽  
Production Chain ◽  
Mesoscopic Simulation ◽  
Fiber Extraction ◽  
Extraction Test ◽  
Material Choice ◽  
Bias Extension Test ◽  
Bias Extension ◽  
Fabric Material

In several fields of engineering the automation of the CFRP production chain is a major issue. In this production chain the forming plays a key role, as the result of the forming influences everything in the chain from the infusion step until the part mechanics. To understand the influence of the material choice onto the forming process is a task followed by many scientists during the last 20 years. Basic tests for shear characterization like Picture Frame Test (PFT) and Bias Extension Test (BiasExt) were developed and used widely. This work deals with the comparison of the BiasExt to a fiber extraction test. The fiber extraction test is developed and used for the characterization of a woven and two non-crimp fabric material. The results are important for the process information and the judgment of primary deformation mechanisms. The tests are simulated for the unidirectional material in a mesoscopic approach and the results are compared in order to judge the capability of the mesoscopic simulation and its residual limitations.

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