In order to be able to work larger fields more efficiently, the performance of agricultural harvesting machines has risen sharply in recent decades. The higher performance of the machines has also increased their weight, which brings manufacturers to the limits of what is permissible under road traffic law and confronts users with greater soil compaction and higher fuel consumption.
This problem was investigated by the IFW together with the project partners Krone GmbH & Co. KG, M&D Composites Technology GmbH and the Institute for Polymer Materials and Plastics Technology (PuK) of the Clausthal University of Technology in the AgriLight research project. By fundamentally rethinking the chassis of the Krone Big X into an innovative fiber composite design, its weight was significantly reduced.
Particular challenges arose from the different material properties of fiber composites and metallic materials, the associated complexity in the design of thick-walled fiber composite structures and the integration of the new, fiber-compatible design into the existing vehicle structure. The new design possibilities of CFRP monocoque construction were used to create additional benefits for the customer. Among them, for example, larger, integrated tanks and simplified cleaning of the machine thanks to closed surfaces. For the design, IFW and PuK jointly investigated a number of different resin systems to find the optimal matrix for the application and the manufacturing process using vacuum infusion without autoclaves. Ansys Composite PrePost was used to perform the finite element simulation. Shell models of the entire CFRP structure were created as well as detailed analyses using solid models. Based on a load spectrum newly developed by Krone, design adjustments as well as optimizations in the laminate structure were made.
In addition to the design and dimensioning of the frame structure, the IFW has also researched new approaches for the fiber composite-compatible introduction of high loads into the frame structure of commercial vehicles. With the aid of the innovative hybrid insert concept, which is optimally suited to the envisaged vacuum infusion process, significantly higher loads can be introduced into the fiber composite structures - together with classic fasteners such as screws and bolts - without the prestressing forces having to be borne by the laminate. The result of the development process is an innovative carbon chassis that offers a weight reduction of 50% compared to the steel frame while providing higher frame stiffness.
In the next step, a prototype of the chassis is produced at M&D Composites Technology. To this end, tooling is first carried out, followed by production of the individual shell components of the monocoque. This prototype is then subjected to dynamic structural testing at our partner Krone, where the developed load spectrum is run on the X-Poster. This will validate the design results and the underlying finite element models. The main objective of this test is to ensure that both the carbon fiber-based chassis and the hybrid inserts used in highly stressed areas do not suffer any damage over the entire lifetime of a vehicle. To record the loads and deformations of the chassis, IFW is implementing a measurement concept that includes Rayleigh and strain gauge sensors as well as optical 3D measurements. Through the development process, IFW has been able to leverage its expertise in the development and design of large fiber composite structures as well as in the conception of application-related force application.
The project is funded by the German Federal Ministry of Economics and Climate Protection (BMWK) as part of the Technology Transfer Program Lightweight Construction (TTP LB). We thank the BMWK for funding the project.
Contact:
For further information, please contact David Garthe, Institute of Production Engineering and Machine Tools at Leibniz Universität Hannover, via telephone +49 4141 77638 24 or by e-mail garthe@ifw.uni-hannover.de.
