The sustainable future of aerospace industry in large part relies on two factors: (i) development of advanced damage tolerant materials and (ii) the ability to detect and evaluate defects at very early stages of component service life. The use of laminated composite materials, such as carbon fibre reinforced plastics (CFRP), has had a significant contribution to reducing airframe weight while improving passenger safety and comfort. However, it is well known that these materials exhibit poor resistance to impact damage caused by foreign objects. Inspired by the naturally occurring impact resistant structures, the first part of this work has shown that enhanced damage tolerance can be achieved with standard CFRP layers by creatively arranging them into bio-inspired configurations. Through an extensive numerical modelling study supported by the experimental results, a further insight into the possibilities that these structures can offer in terms of damage resistance was attained.The second part of this PhD work focused on developing a range of nonlinear nondestructive evaluation techniques that are sensitive to the early signs of material degradation. A range of defect types in metallic and composite structures has been considered, such as fatigue cracks, impact damage and disbonds in adhesively bonded components typical in aerospace industry. Furthermore, throughout this work, an advanced explicit finite element analysis (FEA) software code LS-DYNA® has been used for modelling the nonlinear effects associated with the propagation of elastic waves in damaged solid media.
|Date of Award||30 Jun 2016|
|Supervisor||Michele Meo (Supervisor) & Martin Ansell (Supervisor)|