Using inspiration from natural material science to develop advanced new composite materials designed for impact energy absorption

Birdstrike and impact damage is a major design consideration for the front fan blade in an aeroplane turbine engine. This project explored new materials to minimise the damage to the fan blades under impact. New composite materials called fibre metal laminates (FML) were developed, using aluminium and glass -fibre composite layers to optimise the load bearing and impact energy absorption characteristics of both of the materials . Impact testing of the FMLs showed that the combination of metal and composite improved the impact damage tolerance over either metal or composite alone. The experimental testing was used to verify a computational model, which was then used to further the investigation by modelling the reactions of the material with different material properties throughout the layers.

Impact tested fibre-metal laminate sample with correlating Finite Element Analysis model

After investigating a range of damage tolerant materials from man-made materials to those found in nature, fibre metal laminates (FML) were chosen as the most promising area to investigate further. FML variations using aluminium and thermoset and thermoplastic composite layers were designed and tested using an impact testing machine. Analysis of the impact data and damaged samples identified their modes of failure and the energy at which they failed. This understanding was then used to develop different composite structures and material properties, and computationally tested in a finite element analysis model.

Damage to a aeroplane engine front fan blade
from a mid-air birdstrike
Inspiration from the composite structures in
natural materials and their energy absorption
fracture mechanisms
Schematic of the fibre-metal laminate
composite structure designed to optimise the
different material properties for load bearing
and impact energy absorption

Impact tested samples of the individual
materials which made up the FML composite
Impact tested thermoset glass-fiber epoxy
FML sample; sample did not delaminate thus
the fibers fractured to dissipate the energy
Impact tested thermoplastic glass-fiber epoxy
FML sample; sample dissipated the energy
through delaminating the composite layers
from the metal, thus the fibers did not fracture

Aeronautical Engineering Masters, University of Bristol (2006-7)