Mode II delamination resistance of composites reinforced with inclined Z-pins

Beene M'membe, Sam Gannon, Mehdi Yasaee, Stephen R. Hallett, Ivana K. Partridge
2016 Materials & design  
Z-pin reinforcements in composite materials significantly enhance the through-thickness strength by providing strong bridging forces on the delaminated surfaces of a damaged laminate. The bridging forces have been shown to be more effective in mode I dominated delamination cracks than in mode II shear dominated cracks. One solution to help improve the Mode II delamination resistance of Z-pins is to incline the pins such that the angle between the longitudinal axis of the pin and the shear force
more » ... and the shear force load vector is reduced. In this study, the Mode II resistance of laminated composite reinforced through the thickness with inclined Z-pins is characterised. There is a notable increase in the apparent fracture toughness of composites when Z-pins are better aligned with the shear load vector (inclined) compared to the conventional, orthogonally inserted Z-pins. Brittle, catastrophic failure however occurs when the inclined Z-pins are angled against the shear load vector. For many structures the direction of the local direction of shear load cannot always be predicted, therefore a general approach for inclined Z-pins using a ± θ configuration was also investigated. With this setup, a modest improvement in the apparent fracture toughness was obtained.
doi:10.1016/j.matdes.2016.01.051 fatcat:5cgwjvmw7ba37pdnxjfr72aqeq