Session: 01-04-02: Advances in Aerospace Structures

Paper Number: 137539

137539 - Designing and Optimizing Stiffened-Structure Concepts Using the 3dexperience Platform 

Stiffened structures are widely spread across many industries for their high strength-to-mass and stiffness-to-mass ratios. Furthermore, by tailoring the layouts, cross-sections and material properties of the stiffeners as well as the panel’s skin and material properties (metallic or composite) these structures can enable the design of even lighter structures. However, this vast design space is challenging to explore and determine the most suitable configurations for a desired application taking into account manufacturability process.

The objective of this work is to develop efficient methodologies to design and optimize stiffened structures, by leveraging the unique possibilities offered by the 3DEXPERIENCE platform. Indeed, the challenge is to perform a trade-off between classical layouts (linear, stringer-frame) and more advanced concepts (aniso-grid, curved-grid, free layouts), determine optimal cross-section shapes and sizes, and tailor the distribution of material properties on the panel and along the stiffeners [1,2,3]. Concurrently, the design concepts should remain realistic with respect to manufacturing concerns, for instance by considering discrete subsets of parameter values (e.g. stiffeners with the same shape, only a few different cross-section).

The methodology proposed in this work consists in parametric optimization. In order to explore a wide design domain, on industrial applications and with reasonable computation costs the optimizations are defined such that the number of parameters can remain relatively low. To do so, the method relies on two main approaches: a variable thickness and stiffness skin design, and a modular definition of the laminates and stiffening structure. The variable thickness and stiffness skin design is achieved by dividing the structure into different zones, forming a grid of cells which will have their own material properties. Consistently with industrial practices, the stiffeners are placed on the lines defining the contours of these grid cells. Through the modular approach, a limited set of possible laminates and stiffener cross-sections (hat, J, I), dimensions and layouts (linear, frame-stringer, curved-grid) and are explored, noting the significant topology changes that occur in the latter case. Each module has their own internal parameters to tune the layout and sections. The main advantage of using the 3DExperience is that all the design process is carried out seamlessly between the CAD representation, the construction of the fem model, the simulation, and the automation of the process by design of experiment or optimization algorithms.

The method is applied to conduct a trade-off study on multi-material grid applications, typically the design of a wind turbine blade or of a stiffened fuselage section. The objective is to find the lightest designs satisfying the application requirements (stiffness, strength, buckling, …). The design process that is setup is capable of optimizing an industrial like structure within short times compatible with quick preliminary design iterations.

References

[1] Chen H-J, Tsai SW (1996) Analysis and Optimum Design of Composite Grid Structures. Journal of Composite Materials 30:503–534. https://doi.org/10.1177/002199839603000405
[2] Montemurro M, Vincenti A, Vannucci P (2012) A Two-Level Procedure for the Global Optimum Design of Composite Modular Structures—Application to the Design of an Aircraft Wing-Part2. J Optim Theory Appl 155:24–53. https://doi.org/10.1007/s10957-012-0070-1
[3] Savine F (2022) Simultaneous optimization of unconventional stiffener layouts and composite layups applied to large cylindrical shell structures – PhD Thesis. https://theses.hal.science/tel-03890164v1

Presenting Author: Florent SAVINE Dassault Systèmes

Presenting Author Biography: Florent Savine is a young software engineer at Dassault Systèmes, specialized in the optimization of structures made of laminated composite material. He has successfully obtained a PhD degree in 2022, conducted between CNES, ONERA and Sorbonne Université, which aimed at developing a method to simultaneously optimize the stiffener layout and composite layups of large cylindrical launcher structures. He also has a double degree in engineering between the French Ecole National Supérieure des Arts et Métiers and the Swedish KTH Royal Institute of Technology.