P 1396 – Analysing Failure Behavior of Adhesively Bonded Steel Joints during Material Sparing Debonding in Body Repairs
Current steel-intensive body concepts are based on the combination of different materials in order to take advantage of the different mechanical properties. These highperformance materials are bonded together to form a lightweight body using adhesive bonding technology. Oriented to a typical product life cycle, many research projects are largely concerned with the phases of research and development as well as production and operation. This research project, on the other hand, focuses on the repair and refurbishment of bonded vehicle structures, most of which are carried out by small and medium-sized companies. Increasing demands for safety and comfort lead to the need for viable and sustainable repair methods that produce the same mechanical properties of the bond as the original structure.
In repair shops, bonded joints are often weakened by applying heat to reduce ther equired removal force. However, this process, which is difficult to control, has adamaging effect on the components to be preserved and on adjacent adhesive layers, and leads to severe component deformation. A process that allows bonded steel joints to be de-bonded gently and efficiently brings a decisive advantage and promotes recycling management and resource conservation.
In tests, the embrittlement of the adhesive by low temperatures proved to be very promising for component-conserving separation. In DMTA tests, structural adhesives show a secondary glass transition below the usual application temperature of -40 °C. This is due to the viscous elasticity of the adhesive. This is due to the viscoplasticizing particles in the adhesive. The hypothesis that cooling below this secondary glass transition greatly reduces the energy absorption of the adhesive and thus enables component-conserving removal of the steel materials was confirmed in this work. The possibilities and limitations of this process were successfully investigated and the failure behavior of the adhesive was analyzed.
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Prof. Dr.-Ing. G. Meschut, Dr.-Ing. D. Teutenberg, N. Chudalla, Prof. Dr.-Ing. M. Wibbeke, Dr. A. Bartley