The Free Vibration Characteristics of Canadair NF-5 Aircraft Canopy

Aircraft canopies are transparent covers that enclose the cockpit and provide visibility to pilots. These structures face strong aerodynamic vibrations which may lead them to fail due to the phenomenon called resonance. Hence, it becomes essential to evaluate their natural frequencies and corresponding mode shapes to understand the vibration characteristics of those structures. In addition, it is also essential to comprehend the natural vibration behavior of such structures to conduct further analyses such as forced vibration and dynamic stability. Based on this motivation, this study proposes a preliminary study in which the free vibration behavior of a Canadair NF-5 canopy is investigated by Finite Element Method. For this purpose, polycarbonate and acrylic-based canopies fixed from all mounting edges are analyzed in the ANSYS Workbench environment regarding the first fifteen natural frequencies and corresponding mode shapes. Results indicate that using polycarbonate instead of acrylic increased the natural frequencies of the structure. The displacement regions of the mode shapes of those two canopies are slightly different from each other regarding the displacement amplitudes.