Cast structures score highly in terms of component complexity and low production costs and are therefore predestined for the series production of functionally integrated lightweight structures. Cast iron with nodular graphite (GJS) in particular offers an optimum combination of adjustable strength, ductility and rigidity for lightweight construction.
According to the current state of the art, however, locally varying material properties of components made of GJS, for example due to different component wall thicknesses, are not taken into account in the component design, or only to a very limited extent. For this reason, the Federal Ministry of Economics and Climate Protection (BMWK) is funding the project "Development of a transferable lightweight construction concept for the use of increased cyclic load-bearing capacity of thin-walled GJS structures using a digital twin - GJSlim" as part of the Lightweight Construction Technology Transfer Programme (TTP Leichtbau). This pursues the realisation of particularly thin GJS structures with wall thicknesses of less than 5 mm as well as the determination of technological size influences for component dimensioning. The aim is to develop an overall concept for maximum material and structural utilisation of GJS. The different competences required for this in the disciplines of foundry technology, lightweight structural design and fatigue strength are reflected in the composition of the consortium, which is headed by RWTH Aachen University.
The scientists at the Fraunhofer Institute for Structural Durability and System Reliability LBF have many years of experience in the integration of stress simulation of cyclic material properties for the derivation of findings on the technological, stress-mechanical and statistical size influence of thin-walled cast iron with nodular graphite. They use simulated microstructural states, compare them with experimentally determined findings and thus show the influences of microstructural parameters and the solidification time on local cyclic component load-bearing capacities. The implementation of safe and reliable ultra-lightweight structures will only be possible with an optimised service life assessment, which can be carried out using a design concept to be developed.
Further information on the project: