Fatigue Delamination of Carbon Fiber Fabrics Reinforced PPS Laminates

Abstract

This work analyses the static and the fatigue behaviours and the damage development in satin 5 carbon/PPS fabric composite laminates. First, the orthotropic elastic stiffness matrix of the 0°-ply laminate has been determined by a global mechanical approach in static (tensile, bending and compression tests). Then an elastoviscoplastic model has been identified to describe the 45° oriented sample behaviour during static tests (tensile, creep, torsion and tension-relaxation tests). Finally, fatigue tensile-tensile tests were performed and led to in-situ observations of delamination by using a high resolution camera. The experimental results show that the stiffness evolution follows two stages (decrease after onset and then stabilization) for 0° ply and angle-ply laminates too. This evolution is correlated with damage mechanisms: transverse cracking and delamination. But the maximum stiffness reduction is low and remains in the range of the experimental dispersion. Therefore in the case of a simplified approach, the initiation of delamination can only been identified on static tests. The proposed criterion based on Coulomb friction law was identified thanks to Arcan-Mines tests and the comparison between 2D ½ finite element simulations of tensile tests and experimental results. The home made Arcan-Mines device is an original experimental set-up initially used to qualify adhesive bonding assemblies. It has been modified to determine interface strength in carbon woven fabric reinforced PPS laminates. The main interest of this testing device is to provide multiaxial state of stress going from tension in mode I to pure shear in mode II and compression while always remaining a homogenous state of stress at the interface. The interface strength (in tension or in shear) was used for identification of onset delamination criterion and gives a good agreement between predictions and experimental results.