Influence of Particle Size and Filling Factor of Galfenol Flakes on Sensing Performance of Magnetostrictive Composite Transducers

In this paper, we investigated the influence of particle size and filling factor of flake-type Galfenol powders on sensing performance of Galfenol composite-based magnetostrictive patch transducers. A small demagnetizing field is generally expected for flake-type powders along the in-plane of particles, resulting in enhancing low field sensitivity of the composite patch with well aligned particles. The composite patch composed of the Galfenol flakes and epoxy resin was fabricated with a specially designed uniaxial comb shape to promote magnetic shape anisotropy effect of the patch itself and to enhance directional sensitivity of the patch for guided lamb wave (GLW) applications. The influence of particle size and filling factor of the Galfenol composite patch was evaluated based on the direct A0 mode (the fundamental flexural mode) in received GLW signal data. The linear increase in sensing performance was distinctly observed in the composite patches as the filling factor of Galfenol flakes increased. In addition, the Galfenol composite patches exhibited an improved sensitivity by increasing the size of the Galfenol particles.