The working widths of agricultural machines are constantly being increased for faster and more efficient harvesting. As a result, the weight of the machines increases with each generation. The increased weight increases diesel consumption and therefore CO2 emissions. In addition, the maximum permissible weight of an agricultural machine for road traffic is limited by road traffic authorisation regulations. In order to avoid special licences and reduce CO2 emissions, lightweight construction must be carried out on the machines. A central and heavy component of a harvester is the chassis. This is traditionally constructed as a steel ladder frame. High-strength steels have made it possible to reduce the steel thickness and therefore the weight, but this leads also to reduced chassis stiffness. One solution could be fiber reinforced composites. For this reason, the chassis of the Krone Big X forage harvester was redeveloped from fiber composites in the AgriLight project in order to research its use in agricultural machinery and its weight-saving potential.

The chassis is manufactured in individual shells with vacuum infusion. This allows complex, load- and fiber-compatible shapes to be created without having to invest in cost-intensive aluminium RTM/pressing tools at the prototype stage. The design is based on a large number of variants, material characterizations and Finite Element models. For this purpose, a shell model of the structure was created in Ansys Composite Pre Post and designed with regard to stiffness and strength criteria. In the prototype, the weight was reduced by over 400 kg to 796 kg. At the same time, the simulation promises a 360 % higher torsional stiffness.

The connection points on the vehicle are a central point. These serve as the interface between the conventional steel add-on parts and the fiber composite structure. In addition to the mechanical properties, they must also fulfill the handling requirements of the commercial vehicle industry, which is why the connection point is made of metal. New multi-layer inserts have been developed for this purpose, which produce an intrinsically hybridised area and are cured together with the resin. This eliminates the need for subsequent processing steps such as drilling or gluing. Mechanical testing of the inserts compared to unreinforced samples shows that the load at first fiber failure can be increased by 60 kN (50 %) und the maximum load-bearing capacity can be increased by over 40 kN (26 %).