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Textile composite materials have large deformation characteristics, which leads to the superior formability. However, the large deformation of the textile preform is very much influential on the properties of the molded composite components. Hence, this paper aims at the measurement of large strain distribution in the complex shaped molded components of textile composites. A novel digital image-based procedure is proposed. The Green-Lagrange strain tensor is employed to express the large strain exactly and to avoid the misestimation due to the unmeasureable rotational motion during the closed molding. In pursuit of this, the deformation gradient tensor is calculated by the digitized information from the lattice pattern image drawn on the molded component. The proposed method is demonstratively applied to the deep-drawn components of rib-knitted fabric thermoplastic composites.

The liquid composite molding process involves the coupling between the mechanical behaviors of solids and fluids. To simulate such a process, the evaluation of the permeability is indispensable, while most of previous researches are based on the experimental approach. On the other hand, this paper adopts the mathematical theory of homogenization, which is suitable to numerical analysis. After describing the formulation of the homogenization for solid-fluid mixture, the permeabilities of typical textile composites have been evaluated with the help of the finite element method. Due to the micro-macro features of the method, the consideration of the complex microstructures of knit, woven and “Kumi” cloth has led to not only the three-dimensionally anisotropic permeabilities, but also the characteristic microscopic velocity distribution of the fluids.

This paper proposes a novel design methodology of graded microstructures of functional composites for the emergence of macroscopic function. Micro-macro correlation is analyzed by the homogenization theory. That is, the homogenized properties such as elastic moduli and coefficients of thermal expansion and thermal conductivity are calculated for arbitrary complex microstructures. Then, the functional composites with graded microstructures can be replaced by a homogenized model. Also because it is impossible to design all of the numerous graded microstructures, a discretized model is adopted. To determine the optimum graded arrangement of the microstructures in the discretized model, the genetic algorithm is adopted in this paper. Next, the design of continuously graded microstructures is completed using a feature-based 3D-CAD system. In addition, a solid model is produced by the stereolithography to help the understanding of the designed complex microstructures. Brief description of the formulation of the homogenization method for heat conduction and thermal stress problems are shown. An example of the design of a plate with graded microstructures in its thickness direction to control the macroscopic temperature distribution, thermal strain distribution and deflection is shown.