Finite Element Approach for the Design of Control Algorithms for Vertical Fin Buffeting Using Strain Actuation
Abstract
It is difficult to predict buffet loads during the design stage of an aircraft. The present work describes the control design method used to address this problem for the F/A- 18 aircraft which is often subjected to high- intensity buffet loads that produce high accelerations at the tip the vertical fin during maneuvers at high angles of attack. A NASTRAN finite-element model was constructed to represent the dynamics of the structure at the low frequencies of interest. The aeroelastic frequency response analysis and the thermal analogy available in NASTRAN were used together in a two- step procedure to simulate the strain actuation. This analysis was conducted for each group of actuators to obtain the transfer functions between the two control inputs (actuation groups), the disturbance (buffet load) and the two output variables (a choice among four accelerometers and five strain-gauge positions). Three independent white noise signals limited by the frequency band between 0 and 120 Hz were used in development of a 2x2 MIMO system. The result was a control system using strain actuation to attenuate the dynamic response caused by buffet loads. The predicted results were compared to full-scale test results in the IFOST Program test facility in Australia. The results demonstrated significant reductions in the root- mean-square (RMS) values of the fin dynamic response measured by the strain transducer at the critical point for fatigue at the root were achieved under the most severe buffet condition.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2001
- Accession Number
- ADP011134
Entities
Organizations
- Carleton University