Point fasteners for mechanically loaded sandwich structures

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


The "PuVerSand" project is concerned with the point-to-point bonding 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 lightweight core material in between, for example a foam core.

An innovative connection technology used in this project are inserts that are inserted through a pilot hole in the sandwich structure during the setting process and attached to the upper cover layer by a mechanical forming process. An adhesive system is then injected through the boreholes in the insert and cured. In such applications, the acting forces are transmitted on the one hand via the mechanical fixation to the upper cover layer and on the other hand via the adhesive to the foam and the lower cover layer. The addition of adhesive also locally stiffens the core material, depending on the porosity of the core material and the viscosity of the adhesive.
The advantage of the process lies in the very fast form-fit connection of the insert with the upper cover layer. The load capacity in the axial direction is given immediately. The immediate load capacity in the direction of rotation, which is essential for connecting the components with screws, depends on the curing of the adhesive system used.

The aim of the project is therefore to transfer point-like joining techniques and connecting elements that appear suitable, which are already on the market for other materials, to sandwich composite systems, to examine them and to optimize the overall composite system in terms of design, calculation, simulation and manufacturing processes and thus use the enormous lightweight construction potential of these materials in many areas of application and industry.

15.02.2016 - 15.08.2017