Nichtlineare Auslegung abgestrebter Transportflugzeugflügel

  • Non-linear design of strutted transport aircraft wings

Schmidt, Hauke Gerjet; Schröder, Kai-Uwe (Thesis advisor); Krüger, Wolf-Reiner (Thesis advisor)

Düren : Shaker (2022)
Book, Dissertation / PhD Thesis

In: Aachener Berichte aus dem Leichtbau 1/2022
Page(s)/Article-Nr.: x, 111 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2022

Abstract

Within the design of transport aircraft wings the analysis of the static and dynamic structural properties is essential. Based on the section loads the permissible stresses are determined and the structure is dimensioned. Therein, widely linear methods are used in structural mechanical analysis. This is common practice for small deformations and describes the resulting internal forces with sufficient accuracy. It is assumed that linear calculations are conservative in terms of the maximum stresses occurring in the structure. Due to the use of novel materials and design methods, as well as the development of highflexible configurations, increasing differences appear from linear analysis. Due to large deformations, or additional struts bracing the structure, the structural properties change and lead to a change in the resulting sectional forces. In particular, by longitudinal loading of the structure, the permissible stresses and strains in the system can be considerably larger than according to linear theory. Therefore, especially under the aspect of a variable normal forces, the consideration of the geometric non-linearity effect and the resulting change of the structural properties is needed. Within the scope of this thesis, a preliminary design method under consideration of geometrically non-linear deformations has been developed and subsequently investigated the influence of normal forces. Initially, the resulting section forces have been analysed by taking large deformations into account. Following, the considerable increase of the bending moment due to additional normal force components of strut-braced wing configurations has been investigated based on finite beam elements. The static and dynamic aeroelastic analyses have been carried out for selected flight and mass configurations within the structural design. Based on the maximum and minimum sectional forces the nominal section thickness has been determined by using multi-stage iteration procedures. Due to the number of calculation steps required, parametric models are largely used and the influence of local stiffening elements has been neglected. This methodology allows the identification of non-linear critical stresses within the preliminary design and the investigation of the influence of the structural properties on the dynamic response of aeroelastic systems. Thus, the proposed method shortens the iterative design procedure and enables a non-linear design of highly flexible configurations.

Institutions

  • Chair and Institute of Structural Mechanics and Lightweight Design [415610]

Identifier