Hybridisation of CFRP by the use of continuous metal fibres (MCFRP) for damage tolerant and electrically conductive lightweight structures

Carbon fibre reinforced polymers (CFRP) offer superior weight-specific mechanical properties. However, their brittle failure behaviour limits the structural integrity and damage tolerance in case of impact and crash events. Furthermore, the electrical conductivity is insufficient for certain applications (e.g. lightning strike protection, signal transfer, grounding). Former material concepts tried to resolve these deficits by modifying the resin system, but could not prove sufficient enhancements. A novel approach is the incorporation of highly conductive and ductile continuous metal filaments into the CFRP, thus merging electrical and load-bearing functions within the metal fibres. In this context, the present study focuses on optimising the structural and electrical performance of such hybrid composites with shares of metal fibres up to 20vol.%. Fundamental experiments are carried out on unidirectional as well as on multiaxial (hybrid) laminates. Synchronous improvements of the electrical conductivity, the impact and penetration resistance, the notched properties as well as a pseudo-ductile behaviour can be verified. Additionally, the application of integrated metastable austenitic steel fibres for non-destructive health monitoring by measurement of deformation-induced phase transformations is introduced and discussed.