|Explicit FE simulation of a sandwich compression test of aramide paper as folded core material. The analysis time was 50 ms.|
Description of the project
CELPACT is a research project concerned with development of breakthrough technologies and design tools for future airframe structures with high efficiency and safety. The consortium from five European countries contains seven leading universities with research institutes and aircraft industry partners. The CELPACT project is scheduled on a duration of 3 years.
The main objectives of CELPACT are the development of new sandwich material concepts for primary aircraft structures with higher performance low weight cores designed to enhance impact resistance. The research includes next generation manufacturing techniques for both composite hybrid and metal cellular materials and structures. There will be a wide range of candidate materials and geometries considered: Cellular Hybrid Composites (CHC) with folded composite core structures, Cellular Metal (CM) with closed cell cores and selected laser melted lattice cores.
DLR contribution to the CELPACT project
Working in various EU projects, as for example HICAS and CRAHVI, the DLR has attained extensive knowledge on simulation of high velocity impact on composite and metallic aircraft structures and is now coordinating the CELPACT project.
Within the scope of CELPACT the DLR is establishing numerical FE techniques for the simulation of damage and failure in cellular core sandwich structures under high velocity impact loads from hard and soft projectiles. This includes the development of models for the prediction of the mechanical behaviour of CHC cellular cores and their sandwich structures in terms of core cell geometry, core material and sandwich skin. For efficient computation of large scale structures a multiscale FE modelling procedure is devised for composite sandwich structures which combines the fine scale cellular core models with homogenised models.
The DLR is providing material data for skin and core materials and cellular core structures. For these purposes test programmes are conducted with the ZWICK servo-hydraulic test machines and GOM–ARAMIS deformation measurement system mainly on aramid-paper specimens for CHC cores.
Additionally the DLR realises an impact test programme on generic twin skinned structures with cellular cores under a range of low and high velocity impact conditions. This includes testing with drop tower (12 m height) and gas gun (including large scale bird impact tests). The impact damage to the impacted test structures is assessed by post-test non destructive evaluation.