Model Order Reduction for a Nonlinear Finite Element Model of a Joined Wing Structure

Model Order Reduction for a Nonlinear Finite Element Model of a Joined Wing Structure

Riahi, G.

Tiso, P. (mentor)

Mechanical, Maritime and Materials Engineering

Precision and Microsystems Engineering

2012-07-06

Joined Wing is a concept of nonplanar airplane wing structure. This is a new concept which is not yet used for commercial airplanes but has proven to have several advantages such as lowering the drag and lighter weight combined with higher stiffness. It also increases the maneuverability. However the simulation of the structure using Finite Element Method introduces too many degrees of freedom. Therefore it is necessary to reduce the system of equations using modal order reduction. The common methods of using vibration modes in a reduction basis to reduce the system, fail for nonlinear structures, as with large displacements, the vibration modes of the structure change. Modal derivatives show how a certain mode changes in the direction of another mode. Including modal derivatives in the reduction basis improves the reduction of the model but is very much dependent on the geometry of the structure. In this work, the reduction basis is set up using vibration modes and modal derivatives. It is investigated why this basis fails to reduce the system of the joined wing accurately. By calculating for the remainder, proper orthogonal decomposition and Krylov sequence the reduction basis is improved. Finally a greedy algorithm applied to the joined wing problem succeeds in reducing the system by finding the best possible improvement of the reduction basis for each load step.

nonlinear
finite
wing structure

http://resolver.tudelft.nl/uuid:ab0d4288-3dfd-468d-a6d8-cdafa3ea2164

2012-08-03

Student theses

master thesis

(c) 2012 Riahi, G.