Developing of a repair method for carbon fibre reinforced plastics by using thermally activated oxide semiconductors

• Applicants: Professor Dr.-Ing. Chokri Cherif; Dr. Rolf-Dieter Hund
• Subject Area: Polymeric and Biogenic Materials and Derived Composites ; Lightweight Construction, Textile Technology
• Term: from 2013 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 244448274

The use of fibre plastic (FRP) based on carbon fibre reinforcements in high-tech applications is steadily growing, resulting in the demand and the increasing need for research on appropriate repair concepts for CFRP components.The main objective of this project is to create a scientific basis for the development of a new repair method for CFRP structural components based on thermosets in high-tech applications. It is proposed to completely remove the existing matrix from the damaged region, insert load conforming renewed textile reinforcement layers and then finally to impregnate and consolidate the reinforcements with a suitable matrix. Thereby, the initial load bearing capacity is intended to be achieved without any additional thickening of the original structure.The research objective is to study the efficiency of different inorganic oxides for the local degradation of thermosetting matrix systems based on the predominantly used epoxy resins. A selection criterion is the band gap of the oxide semiconductor, because it significantly affects the activation energy and the associated operating temperature. In connection with the required activation energy of the catalyst and its injection into the local removal of the thermosetting matrix in the repair area, the specific control of matrix degradation is examined. Furthermore, the influence of the metallic oxides on the mechanical properties of carbon fibres (fibre degradation, modulus of elasticity, tensile strength, surfaces energy) and the transition zone between the intact and degraded matrix has to be analyzed. The latter is particularly important for the adhesion of the new matrix material. The possible role of the remaining catalyst materials in reestablished composite and their mechanical properties have also to be explored.For the reestablishment of the load bearing capacity of the composite, a simulation aided analysis is intended for the reconstruction of the new overlapping textile reinforcement layers in the damage of the original structure. Finally, the initial loading bearing capacity of the repaired CFRP structure is restored by the composite formation in the renewed established reinforcing area through impregnation, consolidation with the same vacuum infused thermoset matrix material and subsequent hardening. These studies are initially carried out on rectangular and circular damaged samples.

• DFG Programme: Research Grants