Numerical study on the effects of ply stacking and interlayer toughening on the failure modes and response of OHT laminates

Abstract

The failure modes and deformation response of composite laminates are influenced by multiple factors such as stacking sequence, lamina and interlayer properties, and geometry. One of the critical failure modes in laminated composites is delamination which may lead to premature load drops. This paper investigates the effects of ply stacking and interlayer toughening through a comprehensive numerical study. The numerical framework is the latest iteration of the enhanced semi-discrete damage model (eSD2M) advanced by the authors. The present numerical framework captured the delamination type failure and pull-out failure in open-hole tensile (OHT) laminates, considering both sublaminate-level and ply-level scaled laminates. Experimental and numerical results confirmed that blocked plies can lead to premature specimen failure due to delamination. However, interlayer toughening can delay delamination and improve the structural integrity, even for ply-scaled laminates. On the other hand, interlayer toughening may have adverse effects on sublaminate-level scaled specimens. Ply-level scaled laminates may even outperform them when interlayers are slightly toughened.