Three dimensional finite element model of a non-crimp fabric laminated using geometrically straight tows with crimped material properties

Abstract

The compressive failure of a [0,90]n non-crimp fabric laminate is studied using a 3D finite element model of the representative unit cell at mesoscopic scale. In previous analyses, tow elements coordinate systems were oriented in the actual direction of the fibres. Therefore, the same transversely isotropic mechanical behaviour was employed for every tow element (defined in the element coordinate system). A new approach is presented in this work, in which the geometrical crimp of the tows is neglected and straight tows are created. The actual crimp of the fibres is considered by introducing suitable anisotropic material properties in each zone of the tow. Anisotropic properties have been obtained by a rotation of the actual transversely isotropic mechanical behaviour, taking into account the actual orientation of the crimped fibres. This approach requires a larger amount of work to define the material properties but, on the contrary, the mesh can be easily created for any configuration. Results obtained with the new approach (i.e., the ‘straight tows’ model) have been successfully compared with those of the previous analyses (i.e., the ‘crimped tows’ model).