Magnetostrictive properties of epoxy resins modified with Terfenol-D particles for detection of internal stress in CFRP – Part 1: Materials and Processes

Abstract

Magnetostrictive particles like Terfenol-D are investigated with respect to their ability to detect internal stress generated in carbon fibre reinforced polymers (CFRP) in a non-destructive way. The results are presented in two parts. The first part elucidates the ideas for the preparation of dispersions based on these particles with high den-sity in epoxy resins is introduced. Especially effects of particle size and concen-tration are focussed on. Different particle sizes in a range of 0 - 300 µm are adjusted by special separation techniques. The particle size distribution is controlled in dry state by laser diffraction method. Changing of the chemical composition especially by the oxidation of particles is analysed by EDX. Using a magnetic field is identified as a successful concept for the stabilisation of these high weighted particle fractions dispersed in epoxy resins. The quality of parti-cle size distribution as well as the alignment of particles in the cured epoxy resins is investigated by SEM and light microscopy. The second part of the study presents the magnetostrictive properties of the modified epoxy resins being quantified referring to the detection of internal stress in CFRP.