Bart Verleye

Meso-level textile composites simulations: open data exchange and scripting

The article presents a user interface for modelling of textile composites, which combines open XML input and output formats with scripting for definitions of the reinforcement models under (local) shear, tension and compression deformations. The open input format (parameters of the textile reinforcement) allows easy integration of a meso-level (unit cell) textile processor upstream – with, for example, textile process modelling software or forming models, which define local parameters of the textile reinforcement. The scripting command format makes possible automated processing of the information on local reinforcement deformation conditions, and offers itself to be integrated in user software without accessing or knowing internal computational procedures or native data formats of meso-level textile processor. The open output format allows transferring the results of the meso-level textile processor downstream to meso-level models of the micromechanics or the permeability of a textile composite unit cell. These results can be further streamed to allow macro-level structural, forming or impregnation analysis. The integration approach is illustrated for meso-level textile processor – WiseTex software, integrated with processing of digital images and calculations of the fabric permeability tensor, micromechanics models and meso-level finite element ABAQUS model.

Computation of Permeability of Textile with Experimental Validation for Monofilament and Non Crimp Fabrics

For the manufacturing of composite materials with textile reinforcement, the permeability of the textile is a key characteristic. Using the law of Darcy, permeability can be derived from a numerical simulation of the fluid flow, i.e. by solving the Navier-Stokes or Brinkman equations. In this paper we present the results of simulations with two different flow solvers: a finite difference NavierStokes/Brinkman solver and a lattice Boltzmann solver. The results are validated with theory and experimental data.

User-Friendly Permeability Predicting Software for Technical Textiles

For simulating the injection stage of the manufacturing process of composite materials, the permeability of the textile is an important input parameter. The permeability of textiles can be determined experimentally. However, this is a time and resource consuming process and no standard procedure is yet available. In this paper, we will present a user-friendly software package to simulate the flow through a textile model and predict the permeability Results are presented for a woven fabric and two different non-crimp fabrics. The computed permeability values are compared with experimental results.

Permeability Identification of a Stereolithography Specimen Using an Inverse Method

The simulation of a resin flow through a porous medium by FE-models has become a very important aspect for the design of a high-performance RTM produced composite part. The key parameters to perform RTM flow simulations are the permeability values of the fibre reinforcement. The measurement of this material parameter is still not standardized and thus many different set-ups have been proposed. This paper presents an inverse method, or a so-called mixed numerical/experimental method, for the identification of the permeability values.

Modelling of the permeability of non-crimp fabrics for composites

Abstract: Non-crimp fabrics (NCFs) are mainly used as textile reinforcement for composite materials. The simulation of the production processes of these composite materials requires an accurate value for the permeability of the reinforcement used. Like other textiles, NCFs are porous media and have a permeability value in accordance with Darcy’s law. At the K. U. Leuven, a dedicated solver has been developed for the computation of the permeability of textiles. The complex geometry of textiles and the fine fluid channels makes the computation of the permeability a challenge. NCFs are different to woven textiles. Here, the main source of scatter between experimental results is not nesting, but rather the size of the openings caused by the stitching. In this chapter, the numerical approach is explained in detail and the computed values are compared with experimentally obtained permeability data. A parametric study is performed to reveal the important characteristics that influence the permeability. Also, the influence of shearing on permeability is investigated.

Finite difference computation of the permeability of textile reinforcements with a fast stokes solver and new validation examples

For the simulation of the impregnation process of Resin Transfer Moulding, the permeability of the textile is a key input parameter. Using Darcy’s law, the permeability can be derived from a numerical simulation of the fluid flow for a unit cell problem. In this paper we present the results of simulations with a Stokes solver, implemented in the permeability predicting software FlowTex. The results are compared with those of a Navier‐Stokes solver and validated using theoretical results for model problems and with experimental data for real textiles.