Improvement of Delamination Resistance in Composite Laminates with Nano- Interlayers (Preprint)

摘要

Interlaminar damage in the form of delamination due to the stress concentration is one of the dominant forms in laminated composite structures. One of the approaches to enhance the delamination resistance of the advanced composite structures is to reduce mismatch of elastic properties and the stress concentrations at the interfaces between the laminated layers by utilizing interleave materials. The interleave material considered in this study is a nano-interlayer which can be fabricated in the form of either a thin film of nano-modified epoxy reinforced with vapor grown nanofibers or a fiber mat that can be fabricated with the electrospun fiber process. The nanofibers in the form of a thin film are functionalized with ozone to enhance the interfacial strength between the nanofibers and the surrounding epoxy. To computationally assess the effectiveness of this approach, continuous interface elements of zero thickness are utilized for the characterization of the nano-interlayer. The interface element formulation is based on a cohesive zone model with softening constitutive law. Meanwhile, the experiment was performed with two types of nano-interlayers that are inserted into the laminated composites to monitor initiation and progression of their damage behavior.