Investigation into vibration, aeroelasticity and crack detection of damaged composite wings

This research is focused towards the vibration, aeroelasticity and crack detection of damaged composite wings. Wing damage is considered as a through thickness edge crack for all proposed formulations and numerical tests. A new Dynamic Finite Cracked Element (DFCE) is proposed and applied to cracked uniform composite wings and piece-wise stepped wings. A DFCE provides precise natural frequencies and modes, and used with a new developed multi-crack detection methodology. Moreover, these natural modes have been used in an aeroelastic instability analysis, investigating the influence of a crack on the aeroelasticity of a wing. A new cracked Timoshenko composite Dynamic Stiffness Matrix element is formulated and tested. The free vibration characteristic of a thick cracked beam, where shear deformation significantly alters the natural frequencies, is investigated. This new cracked element provides the analytical solution for natural frequencies of a defective composite thick beam. A strategy for the detection of multiple cracks in wings using natural frequencies has been created and tested. This new strategy involves the implementation of a second indicator. The technique provides highly sensitive results and successfully detects more than one crack for location and size with uncertainty in measured frequencies.