The bending properties of integrally woven and unidirectional prepreg T-sections

The relative bending properties of T-sections produced from three-dimensional (3D) integrally woven preforms and unidirectional prepreg have been investigated with respect to their stress–strain behaviour, skin-stiffener separation loads and fracture behaviour. These tests were carried out to simulate localised skin-stiffener separation that is normally responsible for the failure of postbuckling blade-stiffened composite structures. It has been found that the woven T-sections performed better than their prepreg counterpart in terms of initial and peak failure loads, while at the same time also sustaining less damage which is more contained. Finite element analysis has been carried out to ascertain the suitability of the modified three-point bend test, which also successfully modelled the deformed shape of the T-sections and their critical skin-stiffener separation forces.