| Περίληψη: | Sandwich structures made from composite materials and low-density cores offer high lightweight potential and they are being widely used as load-bearing components in spacecraft structures. Additionally, their mechanical and thermal properties can be tailored to support specific mechanical and environmental loads. A trend increasingly gaining importance in this field is additive manufacturing because a part is printed layer by layer according to a 3D model. Additively manufactured structures can have complex shapes which normally cannot be produced with conventional manufacturing techniques. This technology allows for replacing conventional honeycomb cores with lightweight printed aluminum truss or lattice structures. The freedom of design can be exploited to create core structures which are not only optimized from a structural-mechanical point of view, but also enable the realization of additional functions by design. However, as these rather novel types of sandwich cores offer a wide range of topologies and cell parameters a standard method for modelling and computation does not exist.
With the motivation of driving forward the development of multifunctional sandwich structures, the structural-mechanical and thermal behaviour of different aluminum core structures shall be simulated and analyzed in this thesis with help of the finite element method. Computation of mechanical properties and the numerical modelling of cellular core materials and sandwich structures shall be reviewed. Conventional honeycomb and foam cores and novel printed lattice truss cores are to be considered. Afterwards, beginning with unit cells and continuing with sandwich plates, numerical models will be created to compare the behavior of these structures under mechanical loads. Furthermore, the difference between detailed and homogenized modelling of sandwich cores shall be examined and evaluated. Special focus is to be put on the modelling of load introduction points and boundary conditions. Thereafter, a first assessment of the heat exchange performance indicated by the core types of interest is conducted again through simulation of the former panel models. On the one hand, this thesis shall provide as final result a guideline for the numerical modelling of the different sandwich core structures. On the other hand, a comparison of the stiffness and heat transfer performance between sandwich plates with different aluminum cores is to be drawn.
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