P1234 – Shell structures made of curved sandwich panels
As expected, the research project confirmed that the manufacturing effort for curved sandwich panels is higher than for those with a flat surface. The strategy of range limiting of the possible geometric variations in favour of better manufacturing conditions on the one hand and maximizing them on the other hand by design-specific optimisation was successful. Using the developed design tool for curved sandwich elements, the unrestricted design flexibility in the development of sophisticated building geometries can be ensured and contemporaneously an undesirable and immense manufacturing complexity of curved sandwich panels can be limited. The planner is provided with meaningful design corridors at an early design stage, within which later production will be economically possible. This combination of planning and production ensures the desired research success.
It has also been shown that the geometric classification in 4 complexity levels is completely sufficient to describe all common building geometries with non-planar surfaces adequately. Furthermore, it has been shown that up to complexity level 3, a sufficient number of building geometries are possible, which can nevertheless be manufactured comparatively simple. Also, it was explained how non-planar surfaces can be strategically subdivided in a way that they can be produced with the given boundary conditions (e.g. restrictions due to existing production machines) optimally. With the right approach, roll width and number of forming steps can also be optimized easily. The chronological work steps of: design – optimization – geometric subdivision – production can, supported by now available knowledge, also be improved in repeatable work steps iteratively. As an opensource product, the software tool itself remains capable of future development and can be adapted to coming requirements easily. For the standard user, it remains manageable and easy to use, even without in-depth programming knowledge. This consistent process chain optimization remains a very good principle for the digitalization of the construction industry to realize future building designs in a sophisticated and yet economical way.
The great load-bearing potential of curved sandwich panels was demonstrated by theoretical, numerical and experimental examinations. By this also a basis for further assessment of the mechanical behaviour was derived. In curved sandwich panels as in planar elements the decisive failure mode is stability-based. Wrinkling of the surface which s predominantly under compression will lead to failure in most cases. In the area of application, the curvature has no significant influence on the wrinkling stress.
Prof. Dr.-Ing. J. Lange, M. Sc. S. Grimm, Prof. Dr.-Ing. P. Groche, M. Sc. M. Moneke, Prof. Dr.-Ing. Schäfer, Dipl.-Ing. J. Reising