Controlling the Crack Propagation Path of the Veil Interleaved Composite by Fusion-Bonded Dots.

Guangchang Chen,Jindong Zhang,Puhui Chen,Gang Liu,Miaocai Guo

doi:10.3390/polym11081260

Guangchang Chen, Jindong Zhang + Show 3 more

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https://doi.org/10.3390/polym11081260

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Abstract

This study investigated the effect of the fusion-bonded dots of veil interleaves on the crack propagation path of the interlaminar fracture of continuous carbon fiber reinforced epoxy resin. Two thin fiber layers (i.e., nylon veil (NV) with fusion-bonded dots and Kevlar veil (KV) physically stacked by fibers) were used to toughen composites as interleaves. Result shows that the existence of fusion-bonded dots strongly influenced the crack propagation and changed the interlaminar fracture mechanism. The Mode I fracture path of the nylon veil interleaved composite (NVIC) could propagate in the plane where the dots were located, whereas the path of the Kevlar veil interleaved composite (KVIC) randomly deflected inside the interlayer without the pre-cracking of the dots. The improvement of Mode I toughness was mainly based on fiber bridging and the resulting fiber breakage and pull-out. Fiber breakage was often observed for NVIC, whereas fiber pull-out was the main mechanism for KVIC. For the Mode II fracture path, the fusion-bonded NV dots guided the fracture path largely deflected inside the interlayer, causing the breakage of tough nylon fibers. The fracture path of the physically stacked KVIC occurred at one carbon ply/interlayer interface and only slightly deflected at fiber overlapped regions. Moreover, the fiber pull-out was often observed.

Highlights

The toughness of carbon fiber reinforced plastics (CFRPs) is strongly related to the interlaminar structure [1]
The fracture path of the physically stacked Kevlar veil interleaved composite (KVIC) occurred at one carbon ply/interlayer interface and only slightly deflected at fiber overlapped regions
Non-woven veils formed by a thin layer of fibers have attracted considerable attention as efficient materials for improving interlaminar fracture toughness

Summary

Introduction

The toughness of carbon fiber reinforced plastics (CFRPs) is strongly related to the interlaminar structure [1]. The interlayer toughening method introduces tough or strong materials into the interlayer of CFRPs through an interleaving technology. These tough or strong materials inside the interlayer play the roles of bridging, crack deflection, and viscoelastic energy dissipation, thereby significantly improving the energy dissipation density of crack propagation. Numerous materials can be used as interleaves, such as non-woven veils [3], chopped fibers [4], thermoplastic particles or films [5], and nanoparticles [6,7]. Among these materials, non-woven veils formed by a thin layer of fibers (e.g., nylon veil [3], chopped Kevlar veil [4], and carbon fiber veil [8]) have attracted considerable attention as efficient materials for improving interlaminar fracture toughness. After being interleaved with veils, the Mode I interlaminar fracture toughness (GIC ) and Mode II interlaminar fracture toughness (GIIC ) of CFRPs

Results

Discussion

Conclusion