Influence of Embedded Gap and Overlap Fiber Placement Defects on Interlaminar Properties of High Performance Composites.

Denis Cartié,Christophe Baley,Peter Davies,Marine Lan

doi:10.3390/ma14185332

Abstract

Automated fiber placement (AFP), once limited to aerospace, is gaining acceptance and offers great potential for marine structures. This paper describes the influence of manufacturing defects, gaps, and overlaps, on the out-of-plane properties of carbon/epoxy composites manufactured by AFP. Apparent interlaminar shear strength measured by short beam shear tests was not affected by the presence of defects. However, the defects do affect delamination propagation. Under Mode I (tension) loading a small crack arrest effect is noted, resulting in higher apparent fracture energies, particularly for specimens manufactured using a caul plate. Under Mode II (in-plane shear) loading there is a more significant effect with increased fracture resistance, as stable propagation for specimens with small gaps changes to arrest with unstable propagation for larger gaps.

Highlights

The use of automated fiber placement (AFP) is increasing, as it offers the possibility to produce very complex shapes with tight process control [1]
These results indicate that the short beam shear test, among the most widely used tests to check composite quality, is not very sensitive to the presence of these singularities
It should be noted that this type of interlaminar fracture data for AFP composites with singularities does not exist in the literature, so it is not possible to compare results with published values

Summary

Introduction

The use of automated fiber placement (AFP) is increasing, as it offers the possibility to produce very complex shapes with tight process control [1]. Developed for high performance aerospace applications, the capability for efficient manufacture of complex structures can be applied to marine components such as hydrofoils [2], propellers [3], and tidal turbine blades [4]. These structures tend to be thicker than aerospace composites, so through-thickness properties are more critical. AFP enables the trajectory of unidirectional composite tape to be optimized but laying down complex shapes with this technology can result in defect introduction. Two particular types of defects are possible; gaps between tapes and overlaps where they are superposed

Methods

Results

Conclusion