Relationship Between Matrix Cracking and Delamination in CFRP Cross-Ply Laminates Subjected to Low Velocity Impact.

Riming Tan,Zhidong Guan,Wei Sun,Zhun Liu,Xia Guo,Jifeng Xu

doi:10.3390/ma12233990

Abstract

The effect of matrix cracking on the delamination morphology inside carbon fiber reinforced plastics (CFRP) laminates during low-velocity impact (LVI) is an open question. In this paper, the relationship between matrix cracking and delamination is studied by using cross-ply laminates. Several methods, including micrograph, C-scan, and visual inspection, were adopted to characterize the damage after LVI experiments. Based on the experimental results, finite element (FE) models were established to analyze the damage mechanisms. The matrix cracking was predicted by the extended finite element method (XFEM) and the Puck criteria, while the delamination was modeled by cohesive elements. It was revealed that the matrix crack in the bottom ply not only promoted the outward propagation of delamination but also contributed to the narrow delamination beneath the impact location. Multiple matrix cracks occurred in the middle ply. The ones close to the plate center initiated the delamination and prevented large-scale delamination beneath the impact location. For the cracks that were far away, no significant effect on delamination was found. In conclusion, the stress redistribution caused by the crack opening determines the delamination.

Highlights

Carbon fiber reinforced plastics (CFRP) have been widely applied to aeronautical engineering for several decades due to their high specific strength and stiffness [1]
The main goal of this paper is to figure out the influence of matrix cracking on delamination morphology during low-velocity impact (LVI), especially the undelaminated region beneath the impact location
As revealed by the C-scan and micrograph of the internal damage, delamination only existed at the lower interface

Summary

Introduction

Carbon fiber reinforced plastics (CFRP) have been widely applied to aeronautical engineering for several decades due to their high specific strength and stiffness [1]. Notwithstanding, delamination caused by low-velocity impact (LVI) remains a major concern to researchers since it reduces the residual strength considerably. Researchers have made numerous efforts in the impact mechanisms study and revealed that the delamination is induced by matrix cracking [2,3,4], the formation of the undelaminated region beneath the impact location is still an open question. According to the opinion of Aymerich [5], the through-thickness compression under the impactor during LVI suppressed the delamination. During compression after impact (CAI), the delamination inside a laminate grew into the undelaminated

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