Synchrotron X-ray microtomography at submicrometer resolution was used for investigating the evolution with tensile deformation (up to true strains of 1.8) of the microstructure of a semi-crystalline polymer. Different types of data treatment were performed on the obtained image stacks. Combining analysis in real space with 2D FFT transforms, we were able to show that deformed high density polyethylene does not contain any cavities larger than 1 μm, which contradicts the commonly admitted assumption that whitening of HDPE upon necking is associated with a crazing mechanism. In contrast, X-ray tomography reveals that HDPE deformation leads to the development of density contrasts, the spatial repartition of which is strongly anisotropic.

This paper deals with the modelling of the mechanical behaviour of coated woven fabric. The proposed model takes into account the individual behaviours of the yarns, the coating and their interactions including the influence of the angle variation between warp and weft yarns. This model is able to describe simultaneously the non-Newtonian viscous behaviour, the timeindependent irreversibility, the anisotropy and the cyclic loading behaviour. The model was implemented in the finite element code ABAQUS and enables calculations on structures such as complete sails.