Martin Spieck

State-of-the-Art and Future Trends in Multidisciplinary Design Optimization

The main purpose of this paper is to provide suggestions and stimulus for future research in the field of Multidisciplinary Design Optimization. The paper is based in part on observations from the 2006 European-U.S. Multi-Disciplinary Optimization (MDO) Colloquium that was hosted by the German Aerospace Center in Goettingen, Germany, 1719 May 2006. Seventy participants from industry, academia and government attended the workshop which featured a rich set of presentations, short contributions and discussions. Rather than dwelling extensively on past accomplishments and current capabilities of MDO we focus on the needs and identified shortcomings which lead to potential future research directions. Nevertheless, a brief review of the history and current trends in MDO are provided to set the discussion in its proper context.

AEROELASTIC EFFECTS IN MULTIBODY DYNAMICS.

To enable a realistic assessment of the aeroelastic phenomena of aircraft, a simultaneous application of computational fluid dynamics (CFD), computational structural mechanics and flight mechanics has to be performed. Each discipline has developed powerful specialized tools which have to be adapted for multidisciplinary applications. The combination of CFD and elastic multibody systems is well suited for the simulation of a range of aircraft applications, especially for aircraft ground dynamics. Approaches to a coupling of elastic multibody systems and computational fluid dynamics have been performed using close coupling, that is a modal approach, and loose coupling, that is by co-simulation. In the article the applied programs and the coupling methods are presented. Advantages and limits of using multibody simulation as compared to the direct use of FEA methods for the representation of structural dynamics are discussed. Results of coupled steady and unsteady simulations are presented. Finally, an approach to the aeroelastic trim problem is shown.

Multibody Simulation of the Free-Flying Elastic Aircraft

Multibody simulation is a widely used software tool to simulate the dynamic behavior of an aircraft during maneuvers, landing impacts and other highly dynamic sequences. To enable a realistic assessment, computational fluid dynamics, computational structural dynamics and flight mechanics have to be applied simultaneously. The multibody environment serves as a “virtual testbench” to investigate the overall system, or major components, in their interdisciplinary interaction. This work presents a multibody simulation-based analysis and simulation framework to study the free-flying maneuvering elastic aircraft, concentrating on the underlying problem of adequate representation of aerodynamics in a hybrid multibody system. Three interface levels coupling aerodynamic analysis and multibody simulation are described and illustrated by an application example.