FlexIn Heat®

Flexible, inductive heating to bond and repair fibre-reinforced polymers

Repair applications

This repair concept, developed at the DLR Institute of Structures and Design in Stuttgart, uses flexible induction coils encased in a silicone vacuum mat. This mat allows both the generation of the required temperature and the application of the necessary pressure. For the heating process, inductively heated metal pressure fittings, foils or grids less than 0.3 millimetres thick are cut according to the size of the repair and placed under the mat. Using vacuum pressure, the metal fitting is pressed against the structure to be repaired, ensuring excellent heat transfer. Under this pressure and temperature, the repair component is joined to the main structure.

Application example – bonding

Hybrid metal-composite materials are fnding ever-greater application due to their excellent mechanical properties. One major problem, however, is bonding different components. Most bonding processes require heat to melt either one or both of the parts to be attached, or to melt the joining area. Unlike other kinds of heat generation/transfer, induction heating offers contact-free energy transfer. In the case of fbre-reinforced thermoplastics, only the material in the joining zone is melted and then bonded to the metal after it has cooled. Heating rates of up to 60 degrees Celsius per second and bonding temperatures of up to 400 degrees Celsius also allow the technology to be integrated into a production process with a high cycle rate.

German Aerospace Center (DLR)
Markus Kaden · E-Mail: markus.kaden@dlr.de · DLR.de/en