Textile Composite Deformation Mechanisms

When thermoforming parts from textile composite materials, it is useful to understand the deformation mechanisms, which take place inside them, so that the forming process can be optimized to produce parts of the best quality. The experimental observations and measurements considered in Section 4 are helpful for a general understanding, but do not provide enough detail to reveal the actual mechanisms. The following sections attempt to investigate these mechanisms in more detail. 

The hierarchy of deformation modes for this family of composite materials can be divided into three categories prepieg flow mechanisms, macro-level fabric deformation modes, and micro-level fabric deformation modes, each of which contains a number of different mechanisms. 

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When the textile fabric reinforcement is combined with the matrix to form the composite prepregs, a set of deformation modes are introduced, which may be referred to as top-level deformation modes since they involve the movements of the reinforcement (macro- and micro-level fabric deformation mechanisms) and the matrix. They are in fact the conformation modes of the composite prepreg sheet or group of sheets, as is usually the case, during the forming process. The hierarchy of the top-level deformation modes consist of transverse flow, resin percolation, interply shear and intraply shear, as summarized by Cogswell and revisited by Martin et... 

The drapeability describes the deformation of a textile fabric under its own weight without external loads. The textile can be deformed three-dimensionally. The term drapeability also stands for the deformability of a textile until the first wrinkles appear. The wrinkle-free deposition of a textile on a spherical body requires a two-dimensional deformability of the textile. A wrinkle would impair the mechanical properties. When producing hats, upholstery, or textiles for the reinforcement of composites, this property is crucial. 

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