Helicoidal composites

The behavior of a carbon/epoxy composite material is examined for improved mechanical properties using a design based on a helicoidal architecture. Helicoidal composites with 40 layers, [180/170/160/150/140/130/120/110/100/90/80/70/60/50/40/30/20/10/(0)2] S are used. Through-thickness reinforcement was provided in some of the specimens by the stapling with stainless steel staples. For the helicoidal arrangement, the gradual change in in-plane properties in each layer results in lower interlaminar shear stresses. It is found that the specimen with helicoidal stacking sequence has better debonding resistance and improved damage tolerance. In a tensile test, it is shown that the helicoidal architecture results in higher energy absorption due to limits on the development of transverse cracks. In the circular plate test, the helicoidal specimen shows the highest load and energy absorption. The impact test shows the highest penetration resistance. Some specimens with through-thickness reinforcement were manufactured and characterized. The reinforced laminate presents higher load carrying capacity, better delamination resistance and a graceful failure.