Textile composite mechanics
TexGen has been used extensively for prediction of textile reinforced composite mechanical properties. For some time, TexGen has been employed to generate geometric models of textile reinforcements to permit finite element (FE) analysis of the repeating unit cell in order to determine the effective macroscopic properties of the as-manufactured composite.
Initial work considered the effect of various properties (including yarn (tow) cross-sectional shape, yarn spacing, fibre volume fraction (Vf) and material properties) on the transverse tensile behaviour of single yarns [1].
To overcome problems with meshing the complex matrix volume, a voxel method was developed using the Abaqus[2] commercial FE package. This method divided the unit cell into a regular grid of hexahedral elements, with appropriate local mechanical properties and material orientations defined at the element centroids. This technique was shown to be useful [3], but to improve its efficiency it was modified to incorporate adaptive mesh refinement (AMR). In order to implement AMR for this method, it was re-written to use open source FE libraries and solvers[4]. The use of AMR means that localised mesh refinement occurs around material boundaries and other stress concentrations, leaving coarse meshes in non-critical regions resulting in an automated technique which makes efficient use of computational resources [5]. Using an appropriate continuum damage model, the technique has also been shown to give good agreement with experimentally determined non-linear stress behaviour [6][7]. Figure 1 shows a TexGen model of a unit cell of a plain weave reinforced composite and sections through the corresponding voxel mesh.
For applications where a conformal mesh is required, TexGen's python interface enables a textile model to be accessible from within the Abaqus/CAE FE preprocessor. Scripting methods have been developed to reconstruct the textile geometry in native Abaqus/CAE objects, permitting the automated use of advanced functionality within Abaqus. A typical model generated using this technique is shown in Figure 2.
A fatigue damage model has also been developed for 3D woven composites using a multi scale approach. Evaluation of fatigue damage due to cyclic loading is considered using meso scale (yarns and resin) and micro scale (fibre and resin) models. Failure envelopes are generated at the micro scale, initially using a hexagonal-packed representative volume element (RVE), under cyclic loading conditions. These failure envelopes are used to evaluate the initiation and propagation of fatigue damage in the yarns in the meso scale unit cell model.
References
- ↑ J.J. Crookston, F. Robitaille, A.C. Long, I.A. Jones & J.W. Ooi "A systematic study of the mechanical properties of textile composite unit cells based on geometric modelling", Proceedings of the 14th International Conference on Composite Materials (ICCM 14), 14-18th July 2003, San Diego, USA.
- ↑ Abaqus finite element package http://www.abaqus.com/
- ↑ J.J. Crookston, M.N. Sherburn, L.G. Zhao, J.W. Ooi, A.C. Long & I.A. Jones, "Finite element analysis of textile composite unit cells using conventional and novel techniques", Proceedings of the 15th International Conference on Composite Materials (ICCM 15), 27th June-1st July 2005, Durban, South Africa.
- ↑ libMesh finite element libraries, http://libmesh.sourceforge.net/
- ↑ W. Ruijter, J. Crookston, A. Long & A. Jones, "Computational meso-scale analysis of textile composites using adaptive finite element analysis", Proceedings of the 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials (SDM 47) Conference, 1-5th June 2006, Newport, RI, USA.
- ↑ W. Ruijter, J.J. Crookston, A.C. Long & I.A. Jones, "Modelling of composite materials using FEM and adaptive meshing", Proceedings of the 12th European Conference on Composite Materials (ECCM 12), 29th August-1st September 2006, Biarritz, France.
- ↑ J.J. Crookston, W. Ruijter, A.C. Long & I.A. Jones, "Modelling mechanical performance including damage development for textile composites using a grid-based finite element method with adaptive mesh refinement", Proceedings of the 8th International Conference on Textile Composites (TexComp 8), 16-18th Oct 2006, Paper T09, Nottingham, UK.
