Detection of fibre fracture and ply fragmentation in thin-ply UD carbon/glass hybrid laminates using acoustic emission

Putu Suwarta,Gergely Czel,Mohamad Fotouhi,Michael R Wisnom,Meisam Jalalvand

doi:10.1016/j.compositesa.2016.04.003

Abstract

This paper investigates the link between acoustic emission (AE) events and the corresponding damage modes in thin-ply UD carbon/glass hybrid laminates under tensile loading. A novel configuration was investigated which has not previously been studied by AE, where the laminates were fabricated by embedding thin carbon plies between standard thickness translucent glass plies to produce progressive fragmentation of the carbon layer and delamination of the carbon/glass interface. A criterion based on amplitude and energy of the AE event values was established to identify the fragmentation failure mode. Since the glass layer was translucent, it was possible to quantitatively correlate the observed fragmentation during the tests and the AE events with high amplitude and energy values. This new method can be used as a simple and advanced tool to identify fibre fracture as well as estimate the number and sequence of damage events that are not visible e.g. in hybrid laminates with thick or non-transparent layers as well as when the damage is too small to be visually detected.

Highlights

IntroductionGradual failure and pseudo-ductile stress–strain response in thin carbon/glass plies were observed by Czél and Wisnom [7,8,9] and Jalalvand et al [10]
Hybridisation of different continuous uni-directional (UD) prepregs is a successful method to address the lack of ductility in composite laminates
Their results showed that as the failure strain of carbon fibres is lower than that of the glass fibres, the first damage occurs in the carbon layer and the following failure mechanisms in the specimen are influenced by the interfacial toughness, material properties, and the thickness of the layers

Summary

Introduction

Gradual failure and pseudo-ductile stress–strain response in thin carbon/glass plies were observed by Czél and Wisnom [7,8,9] and Jalalvand et al [10]. Their results showed that as the failure strain of carbon fibres is lower than that of the glass fibres, the first damage occurs in the carbon layer and the following failure mechanisms in the specimen are influenced by the interfacial toughness, material properties, and the thickness of the layers. In another study by Jalalvand et al [11,12] the effect of the configuration parameters on damage evolution in UD

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