Project Image:
Title of the project:
Point-shaped connecting elements for mechanically loaded sandwich structures
Project leader:
Dipl.-Ing. Sebastian Wagner
Project management:
  • Ministerium für Wirtschaft, Arbeit und Wohnungsbau Baden-Württemberg
Funding reference number:

Sandwich structures have a high potential for use as load-bearing components in vehicles. One challenge is the joining concept of these sandwich components, especially with regard to detachable joints. Due to the inhomogeneous structure of the sandwich structures, conventional punctiform detachable fasteners such as screws cannot be used directly.


The project "PuVerSand" deals with the point-like joining of sandwich structures. Sandwich panels have a high potential for use as load-bearing components in vehicles and consist of two cover layers with a light core material in between, for example a foam core.

An innovative joining technique used in this project is inserts, which are inserted into the sandwich structure during the setting process through a pre-hole and fixed to the upper surface layer by means of a mechanical forming process. Subsequently, an adhesive system is injected through the drill holes in the insert and cured. With such inserts, the forces acting are transferred to the upper cover layer via the mechanical fixation on the one hand, and to the foam and the lower cover layer via the adhesive on the other. The adhesive application also stiffens the core material locally, depending on the porosity of the core material and the viscosity of the adhesive.
The advantage of this process is the very fast, positive connection of the insert to the upper cover layer. The load capacity in axial direction is given immediately. An immediate load-bearing capacity in the direction of rotation, which is indispensable for connecting the components by means of screws, depends on the curing of the adhesive system used.

The aim of the project is to transfer and investigate the seemingly suitable punctiform joining techniques and connecting elements, which are already on the market for other materials, to sandwich composite systems and to optimize the overall composite system with regard to design, calculation, simulation and manufacturing processes, thus enabling the enormous lightweight construction potential of these materials to be used in many areas of application and industry.

Project partners:
  • ARENA2036 e.V.
  • Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) - Institut für Fahrzeugkonzepte
  • DYNAmore GmbH
  • EJOT GmbH & Co. KG
  • Fraunhofer-Institut für Kurzzeitdynamik (EMI)
  • Fraunhofer-Instiut für Werkstoffmechanik (IWM)
  • Hymer GmbH & Co. KG
  • Leichtbau BW GmbH
  • SECAM Fixing Solutions
  • Sika Deutschland GmbH