• Köke, Hardy
• Hühne, Christian
• Weiß, Lennart

Abstract

The full lightweight potential of carbon fiber reinforced plastics in complex structures can onlybe exploited using an adequate combination of material and design. Potential combinations can be found, usingan optimization routine integrated into the design process. This paper presents a detailed comparison of theoptimization results for distinctive rocket interstage design concepts. The complex cylindrical grid structure hasto withstand the mission loads while being as light as possible. For the efficient use of the superior materialproperties, carbon fiber reinforced plastics are combined with a foam core to form a sandwich configuration.To minimize the total mass, parametric finite element models are used within a constrained, mixed-integeroptimization. The structure is modeled using a bottom up strategy. An optimization framework, incorporatingthe CAE software Ansys into the multi-purpose optimization package pyOpt, is presented. The augmentedlagrangian particle swarm algorithm is used to find the configurations having minimal weight. As manufacturabilityis an important design requirement, a winding process is represented by constraints in the parameter set ofthe geometry. The stiffnesses of the structure, as well as strength criteria of the laminate are used as inequalityconstraints for the optimization. Further on, a lower bound of the first natural eigenfrequency using additionalconstraints, is investigated. Finally, the impact of the governing geometry, material parameters and hence theirinfluences on the optimization problem are carefully reviewed. It is shown that appropriate design – materialcombinations can significantly reduce the structural mass.

Topics

• impedance spectroscopy
• polymer
• Carbon
• strength