SOME ASPECTS OF AN EXPERIMENTAL INVESTIGATION ON COMPOSITE AEROBATIC AIRCRAFT STRUCTURE.

There is a growing trend to employ composite materials in the development and construction of aircraft structures in keeping with the desire for lighter but stiffer structures. The Al aerobat is an aircraft that has contributed extensively towards the field of research and has had a significant influence on education in aeronautical engineering. The present work deals specifically with the initial investigation of the dynamic characteristics of a Carbon Fibre Reinforced Plastic (CFRP) wing box. This wing box is designed and developed at Cranfield University, which is representing the wing box of the Cranfield Al aerobatic aircraft. The root of the wing box is attached to a large rigid concrete structure to serve as an ideal foundation simulating a root fixed boundary condition. The composite wing box is excited using random and sinusoidal excitation methods in the frequency range of 0 to 300 Hz. A total of five test locations are conducted in order to measure the response of the entire wing box. Results obtained are in terms of eigenvalues and eigenvectors. These results are presented, discussed and the vibration experiment used to obtain these results discussed. The primary objectives of these investigations are to study the dynamic characteristics of a real composite aircraft lifting structure by way of accomplishing a practical task and to provide a realistic mechanism for education in the field of aeronautical engineering.