Investigation and optimization of mechanical behavior of stiffened curved composite panels used in aerospace subjected to under low velocity impact

Material technologies in the aviation industry are advancing day by day. Building materials produced with wood have been developed with many alternative options such as high-tech alloys, composites and nanotechnological materials. The use and optimization of these materials is also important for aviation. In this thesis, studies on the optimization of the impact behavior and mechanical properties of stiffened curved and flat plates forming surfaces such as fuselage, wing and tail of aircraft have been carried out. The effect of mechanical properties of plates and stiffeners such as stacking direction, thickness, number of layers and layer thickness on impact behavior has been investigated. Damage after impact can grow and act like cracks due to the dynamic loads applied on the aircraft and may eventually result in the failure of the main structure. Within the scope of this thesis, the optimization of deformation and vibration behaviors as a result of impact was carried out using artificial neural network (ANN) and Taguchi L9 method. The deformation and acceleration values on the plates were minimized. Carbon T700 material was assigned to appropriate geometry models by finite element method and low velocity impact tests were performed and contact force, acceleration, energy absorption and displacement data were extracted. For vibration analysis, Fast Fourier Transform (FFT) analysis was performed on the raw acceleration data and dominant frequency values were obtained. By predicting the acceleration values using the ANN module, the structure with the mechanical properties with the lowest acceleration value was determined.