Prediction of delamination resistance in laminated composites with electrospun nano-interlayers using a cohesive zone model

초록

Nano-interlayers were fabricated with polycarbonate by using an electrospinning process to improve delamination resistance in laminated composites. The laminates were laid up with and without the nano-interlayers having the stacking sequence of [30/-30/90]s and tested under uniaxial tensile loading. Five nano-interlayers in the form of the electrospun nanofiber mats were placed at every ply interfaces. Thickness difference of the laminates with and without five nano-interlayers is less than 0.001 mm. First-ply-failure stress, delamination stress and ultimate strength increased 8.4%, 8.1% and 9.8% with the addition of the nano-interlayers as compared with the pristine specimens. The number of microcracks at the delamination stress decreases significantly by 21.6% with the addition of the nano-interlayers. Therefore, the ultra thin electrospun nano-interlayer cannot only suppress the microcracking and delamination damage by reducing the interlaminar stress concentration at the free edges in the laminated composites, but increase the ultimate strength property as well. A nonlinear finite element analysis was performed using interface elements based on a cohesive zone model to predict the delamination resistance of the laminates with the insertion of the electrospun nano-interlayers under the unidirectional tensile displacement loading. The laminated composite with the interface elements simulating the nano-interlayers was modeled with 3-D eight-node hexahedral solid elements and interface decohesion elements having a bilinear constitutive relation. Parameter studies were carried out with various critical energy release rates and interfacial strengths. Copyright © 2006 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.