A NEW METHOD FOR MODELING LARGE FLEXIBLE STRUCTURES

The emergence of electronic flight-control systems into commercial air craft designs has precipitated and immediate need for nonlinear, discr ete-time analyses in both frequency and time-domains, for both the air craft Structural Dynamic Loads and the Flight Controls communities. Th is paper presents and demonstrates a methodology by which the large-sc ale, linear aircraft structural models produced by the Structural Dyna mic Loads community can be easily reformulated using EASY5x. EASY5x t hen provides and environment for incorporating nonlinearities and disc retization; and moreover, it provides an intuitive and tractable envir onment for engineers who are not well versed in linear analysis techni ques to manipulate and analyze both the plant and its interactions wit h a nonlinear, discrete-time control system. The paper then goes on to present a method for transforming the large-scale linear plant into t he z-domain using EASY5x. The resulting state-transition matrices prop agate the exact solution to structural model equations of motion so si mulation accuracy is greatly increased while run-time for statisticall y significant simulated time intervals is dramatically reduced. Furthe rmore, the analysis is brought into the efficient, graphically driven environment of the engineering workstation.