Meso-Level Bending/Reverse-Bending Analysis of Dry Woven Fabrics: Observing an Irreversible Behavior during Forming

2021 ◽  
pp. 115124
Author(s):  
R. Sourki ◽  
B. Crawford ◽  
R. Vaziri ◽  
A.S. Milani
Keyword(s):  
Woven Fabrics ◽  
Meso Level ◽  
Bending Analysis

An advanced geometrical model for laminated woven fabrics using Lamé exponents with enhanced accuracy

2017 ◽  
Vol 52 (11) ◽  
pp. 1443-1455
Author(s):  
Mike Mühlstädt ◽  
Wolfgang Seifert ◽  
Matthias ML Arras ◽  
Stefan Maenz ◽  
Klaus D Jandt ◽  
...  
Keyword(s):  
High Performance ◽  
Volume Fraction ◽  
Level Structure ◽  
Three Dimensional ◽  
Geometrical Model ◽  
Woven Fabrics ◽  
Fiber Volume ◽  
Meso Level ◽  
Precise Prediction ◽  
Microscopy Images

Three-dimensional stiffness tensors of laminated woven fabrics used in high-performance composites need precise prediction. To enhance the accuracy in three-dimensional stiffness tensor prediction, the fabric’s architecture must be precisely modeled. We tested the hypotheses that: (i) an advanced geometrical model describes the meso-level structure of different fabrics with a precision higher than established models, (ii) the deviation between predicted and experimentally determined mean fiber-volume fraction ( cf) of laminates is below 5%. Laminates of different cf and fabrics were manufactured by resin transfer molding. The laminates’ meso-level structure was determined by analyzing scanning electron microscopy images. The prediction of the laminates’ cf was improved by up to 5.1 vol% ([Formula: see text]%) compared to established models. The effect of the advanced geometrical model on the prediction of the laminate’s in-plane stiffness was shown by applying a simple mechanical model. Applying an advanced geometrical model may lead to more accurate simulations of parts for example in automotive and aircraft.

On the Effect of Uncertainty Factors on Mechanical Behavior of Woven Fabric Composites at Meso-Level

2009 ◽  
Author(s):  
Mojtaba Komeili ◽  
Abbas S. Milani
Keyword(s):  
Computer Experiments ◽  
Woven Fabrics ◽  
Unit Cell ◽  
Woven Fabric ◽  
Meso Level ◽  
Woven Fabric Composites ◽  
Fabric Composites ◽  
Geometrical Defects ◽  
Noise Factors ◽  
Fiber Misalignment

Unit cell modeling of woven fabric composites at meso-level has been advantageous in finding equivalent mechanical properties of different weave architectures without performing physical experiments on each new fabric. The obtained properties, in turn, can be used in the macro-level modeling and simulation of large composite structures. Models used for this purpose, however, often consider a perfect description of unit cells, while in practice fabrics are not always fabricated under ideal conditions and flaws like fiber misalignment, material and/or geometrical defects are present. A benchmark work covering effects of this kind on the mesoscopic behavior of woven fabrics is underway. The aim of this paper is to present a statistical way to approach the problem by studying the main effects of such uncertainty/noise factors along with their levels of significance. Namely, a one-factor-at-a-time screening method is selected to identify the effect of (1) fiber misalignment, (2) fiber modulus variation, (3) geometrical flaws in yarn section, (4) unpredictable friction between weft and warp yarns. Computer experiments are done using FE modeling of a plain weave unit cell under the uniaxial, equibiaxial, and trellising (shear) modes. A parameter sensitivity analysis is conducted to identify the most significant factors and the extent to which each can independently contribute to the variation of load-displacement curves (i.e., testing data non-repeatabilities).

A migration industry for skilled migrants: the case of relocation services

2018 ◽  
Vol 15 (4) ◽  
pp. 545-559 ◽  
Author(s):  
Florian Tissot
Keyword(s):  
International Schools ◽  
Basic Needs ◽  
Skilled Migration ◽  
Meso Level ◽  
Key Informants ◽  
The Family ◽  
Private Actors ◽  
Migration Industry

The aim of this article is to clarify the role of the organisations that support skilled migrants after a relocation, using the analytical concept of migration industry. The concept is used as a tool to explore the gap between the macro and the micro levels and by that stresses the crucial meso-level when it comes to conceptualizing (skilled) migration. I use 30 semi-directive interviews with skilled migrants and six interviews with key informants in the migration industry as a basis for the analysis, leading me to distinguish three main services at the heart of this industry. Each service is covered by distinct private actors: the basic needs of the family by relocation offices, the education of the children by international schools, and the careers of the partner by outplacement agencies.

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