Experimental analysis of high velocity impacts of carbon/epoxy composite fragments

Abstract

The aeronautical industry tries continuously to find different strategies to optimize structural components with the aim of reducing their weight and hence achieving a more sustainable transport. The new developments that will come in the following years, will probably use incorporate open rotor engines since they have lower consume. These engines have a series of counter-rotating blades made of composite materials, which could impact the aircraft fuselage in case of failure. Impacts on aeronautic structures can be caused by rigid (metallic fragments), or by highly deformable bodies (hail, bird). Apart from these, which have already been studied, there are other types of impacts, practically unexplored, which are the fragments of carbon/epoxy laminates. In this work, high speed impact tests of carbon/epoxy fragments have been carried out in a wide range of impact velocities, from 80 to 190 m/s. These tests have been monitored using high-speed cameras which, using a specific tracking software, could calculate their acceleration and therefore the force exerted. The erosion suffered during impact has also been quantified. In order to study the failure process, a simple analytical model has been proposed to evaluate the influence of the different mechanisms of energy absorption during the impact and hence predict the erosion of the fragment during the impact.