
A Preliminary Study of an Aeronautical Multi-Stable Composite Stiffened Panel
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Traditional aeronautical structural design avoids buckling because it can generate large nonlinear deformations and induce complex damage behaviour, further threatening structural integrity and load capacity. However, design space can be expanded to promote structural efficiency and potential functionality if buckling is allowed in a controlled and predictable manner [1]. For instance, multi-stability can be introduced into a structure when different buckling modes appear. It provides potentials for shape adaptability without the need of continuous energy input [2] while maintaining the structure’s original load capacity, being a promising solution to reduce energy consumption for operation of aeronautical structures. Considering these fundamental advantages, we aim to propose a layup configuration for stiffened composite panels that can exhibit multi-stability by buckling mode switches with increasing loads. As a preliminary study, the layup configuration should support buckling mode switching and easy hand laminating. The loading scenario for the proposed design is uniaxial compression. To achieve this objective, a carbon fibre/epoxy composite panel (material: IM7/8552; dimensions: 230 mm × 300 mm) with four vertical stiffeners is designed. This allows the panel to be divided into three regions, as shown in Figure 1a. By tailoring the layup configuration in the three regions, it is possible to observe the bucking starting in the central region and then expanding in the two lateral ones, as shown in Figure 1b. Eigenvalue analysis and post-buckling dynamic implicit analysis were performed in ABAQUS. Static compression tests will be conducted to validate the proposed layup configuration, and the results will be presented at the conference.