Layout Topology Optimization of Unconventionally Stiffened CFRP-Structures Considering Manufacturing Constraints (OptiFee)

• Applicants: Professor Dr.-Ing. Berend Denkena; Professor Dr.-Ing. Sebastian Heimbs, since 9/2022
• Subject Area: Lightweight Construction, Textile Technology ; Production Automation and Assembly Technology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 450687126

In the topology optimization of stiffened lightweight structures, for example aircraft fuselage structures, mass and production cost are commonly used as optimization criteria. In order to assess these criteria a detailed design of the structure is required which can only be obtained at high computational cost especially for unconventional structures. Additionally, the use of unconventional structures increases the impact of manufacturing constraints as well as the challenges in computing production costs. Therefore, topology optimization in the early design phases of aircraft structures is currently mostly applied to conventional stiffening layouts. Possibilities for mass reduction due to the use of CRFP, fiber compatible design and locally adapted stiffener design are not utilized.The scope of this project is therefore to develop and research a method which enables the assessment of structural mass and production cost as well as manufacturing constraints of unconventional stiffened structures with reduced computational effort. The method utilizes a new integrated structural and production design process which is based on allowable ranges for the different geometry and material parameters instead of a specific detailed design. Using substitute models in combination with reduced FE-models shows potential to decrease computational cost in the structural design process. A high number of substitute models for various design criteria are already successfully applied to conventional structures. The IFL will therefore research the possibility of applying reduced FE- and substitute models to the assessment of detailed design criteria for unconventional structures. This also requires the development of substitute models for non-rectangular skin sections and complex stiffener crossings.The required methods to compute production costs such as methods for process planning and cost models are mostly available for metallic structures and based on detailed structures. Transferring those methods to process chains specific to CFRP structures is not always straightforward. This also applies to manufacturability criteria. The IFW will extend existing methods for chosen CFRP processes based on technology simulations. Additionally, the applicability of a comparative cost criterion based on parameter ranges will be tested. The necessary manufacturability criteria for complex stiffener crossings will be deducted from a series of manufacturing tests. Finally, the application of the different new methods within a topology optimization will be tested. For this, parameter studies concerning the solution space and the used algorithm are carried out

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr.-Ing. Peter Horst, until 8/2022