Paper number 1159


C. Jung1, J.F. Ganghoffer2 and B. Durand1

1Laboratoire de Physique et Mécanique Textiles de Mulhouse. ENSITM. 11 rue Alfred Werner, 68093 Mulhouse cedex, France.
2Institute for Chemistry and Physics of Interfaces - CNRS - 15 rue Starcky, BP 2488, 68057 Mulhouse cedex, France.

Summary Woven textile materials exhibit interesting and new features, compared to standard materials, such as negative Poisson's ratios, revealed by measurements of the variations of fabric lateral dimensions, using an optical extensometer. Micromechanical models of fabric have been elaborated, following two different lines of thoughts. In the first approach, the mere yarn is modelled as an undulated beam ; a perturbation method allows to obtain an equivalent representation of the yarn as a straight beam, the equivalent coefficients of which keeping a trace of the initial undulations. In the second approach, a unit cell is defined as one undulation of the yarn, and the rotation of the unit cell with respect to a fixed basis defines a microrotation, which enters into the kinematical description of fabric as an additional rotational degree of freedom at an intermediate scale.
Keywords mechanics of textile, negative Poisson's ratio, micromechanics, micropolar material, thin plate model.

Theme : Composite Structures ; Modelling

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