Date

2017

Author

Özkaya, Özge

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Accurate prediction of the static aeroelastic behavior of the lifting surfaces is crucial since aeroelasticity triggers instabilities, changes the load distribution and affects the control effectiveness and thereby the overall performance of the aerospace structures. Composite structures are prone to failure either because of the defects which may occur inside the structure during the manufacturing or in service. Damages are both inherent and unavoidable in composite materials and some of them are hard to detect. Therefore, aeroelastic behavior of damaged composite lifting surfaces has to be investigated for an effective design. This study presents the nonlinear static aeroelastic behavior of composite missile fins with induced interlaminar and intralaminar damages. For this purpose three-dimensional finite element models of composite missile fins with interlaminar and intralaminar damages in different locations are prepared. Different regions such as the leading edge, trailing edge and tip of the missile fin which are typical locations where disbonds are very probable are left open to simulate the delamination while the rest is kept bonded. Intralaminar damage is created by degrading the stiffness of the structure at critical locations in the missile fin after the fin is exposed to a harsh flow condition which in a way simulates a critical maneuver of the missile during which the fin structure is overloaded causing intralaminar failures. Critical locations are determined by applying harsh flow condition on the composite missile fin and identifying the failed regions according to the Puck failure criteria. One-way and two-way coupled static aeroelastic analyses of the undamaged and damaged composite missile fins are performed to predict the effect of pure interlaminar, intralaminar and combined interlaminar and intralaminar damage modes on the pressure distribution, lift, deformation and the stress state of the damaged fin and comparisons are made with the undamaged missile fin. It is shown that besides the effect of the interlaminar and intralaminar damages on the stress state in the composite fin structure, the interlaminar and intralaminar damages in the composite fin structure may lead to significant differences in the lift acting on the fin, compared to the undamaged fin, which in turn may affect the control effectiveness and thereby the overall performance of the missile. 

Subject Keywords

Aerofoils., Aeroelasticity., Rockets (Aeronautics), Composite materials

URI

http://etd.lib.metu.edu.tr/upload/12621509/index.pdf 
https://hdl.handle.net/11511/26724

Collections

Graduate School of Natural and Applied Sciences, Thesis