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Generation of Realistic Stochastic Virtual Microstructures Using a Novel Thermal Growth Method for Woven Fabrics and Textile Composites



Generating realistic 3D tow-level finite element (FE) models of textile weaves and impregnated textile composites poses a challenge because of the complexity of the 3D architecture and the need for achieving high quality finite elements and nonintersecting tow volumes. A common approach sweeps a constant tow cross-section along a smooth and continuous centerline that repeats over a unit cell length. However actual microstructures of dry fabrics and textile composites are often aperiodic and non-deterministic. In this study, we present a novel method to generate realistic virtual microstructures of fabrics and textile composites using a “thermal growth” approach. This involves a series of orthotropic volumetric expansions and shrinkages of the tow cross-sections and centerlines that are artificially induced by prescribed thermal loads, along with mechanics-driven tow deformations in order to grow or form the tows into their final realistic configurations within the weave. Contact-pairs are defined between interlacing tow surfaces to prevent tow inter-penetrations. The final virtual microstructures are generated through a series of simulations executed using LSDYNA. Two case studies are presented. The first is a plain-weave Kevlar fabric used in protective structures. The second is an angle-interlock PIP-CVI processed C/SiC ceramic matrix composite used in high temperature structures. The virtual microstructures are validated against experimental microstructures obtained from SEM, optical, and microCT characterization. Relatively fine features are generated correctly, including variations in tow shapes and the distribution of spacings that are left between tows. This novel thermal growth approach to generate 3D tow-level meshes of weave architectures can be applied towards any 2D, 2.5D, and 3D woven, braided, and knit architectures. The generated virtual microstructures are at the core of Teledyne’s ICME-based virtual testing toolset to predict the linear thermoelastic and non-linear thermostructural damage behavior of textiles, PMCs, and CMCs.

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