Fraunhofer Institute for Wood Research Hannover Messe 2025:
Researchers from the Fraunhofer WKI present bio-based sandwich component for lightweight construction
Researchers at the Fraunhofer WKI have developed a bio-based, three-dimensional sandwich structure specifically for lightweight-construction applications in the mobility sector, which is suitable for incorporation into the shell of a caravan. The scientists increased the proportion of renewable raw materials and, at the same time, avoided the utilization of dissimilar materials in order to improve recyclability within the closed loop. The sandwich component can be seen on the Fraunhofer joint stand at the Hannover Messe from 31st March to 4th April 2025.
The innovative sandwich component made from lignocellulose and bio-based epoxy resin, which the researchers are presenting at Hannover Messe 2025, replicates the cross-section of a caravan wall structure with inner and outer walls. In the future, the material could be utilized in, for example, sleeping cabins in trucks or motorhomes. The advantages of the new development lie in the homogeneous sandwich structure of complex geometries and the complete recyclability that the researchers are striving for with the material.
The special feature of the solution approach is that the foaming process for the core layer and the impregnation and consolidation of the top layers are performed in the same near-net-shape mold. “In our technical center, we use special spacer fabrics for this purpose; as a result of their pile yarns, the fabrics enable mechanical interlocking of the top layers with the core layer, thereby preventing delamination of the top layers,” reported Ole Gonnsen, Project Manager at the Fraunhofer WKI.
As the material basis for the foam and the reinforcing textile, the researchers are using lignocellulose. The plastic component consists of a bio-based epoxy resin. The expansion of the foam is performed under controlled temperatures and pressures. Subsequently, the resin is added under pressure in an injection process and cured in order to solidify the top layers.
The researchers have succeeded in foaming various wood-foam mixtures of differing densities in a spacer fabric made from flax fibers to create close-contour structures. A special hydrophobization of the wood foam ensures that the penetration of the resin into the wood foam is limited to a desired level during the injection process. The use of natural-fiber-reinforced plastic recyclates as hydrophobing agents has also been identified as promising by the scientists. This facilitates the reutilization of the materials.
Substitution of petroleum-based products in the automotive industry:
Do bio-based alternatives work?
“In our feasibility study, we were able to achieve a general proof of the functionality of the concept, i.e. Technology Readiness Level 3. With our bio-based material, we see great potential for enhancing the recycling capability of mobility. In order to further develop our research and to adapt it to the practical requirements of industry, we are currently seeking project partners from various mobility sectors. We are therefore looking forward to discussions with the industry at the Hannover Messe in order to find out about their needs and requirements,” reported Ole Gonnsen.
Last modified:
