MULTIDISCIPLINARY OPTIMISATION OF FLEXIBLE AIRCRAFT IN FLIGHT WITH SUPERIMPOSED STATIC AND DYNAMIC AEROELASTIC LOADS

摘要

Shorter development cycles and a reduction in available engineering resources, especially in military aircraft design, lead to a desire to increase the level of automation in the design process, particularly with respect to iterative tasks such as the so called load loops between the determination of aeroelastic loads on the aircraft and the sizing of the structure. An important tool in this respect is Multidisciplinary Design Optimisation, posing the design problem as a mathematical search for a design vector fulfilling all necessary constraints while minimising a given objective function. This paper describes how ongoing work at Cassidian Air Systems has extended the in-house optimisation programme LAGRANGE to include dynamic aeroelastic loads in the optimisation process and superimpose these on, for example, a static flight condition to simulate a gust encounter in flight. An example for the structural sizing of the fuselage of a MALE reconnaissance aeroplane is given, demonstrating the extents and size of the criteria model necessary for practical industrial applications. Finally, a method to include a linear gust load alleviation system via transfer functions of arbitrary order in the sizing process is described.