Theoretical and experimental investigation of magnetostrictive composite beams

Among novel non-destructive evaluation techniques for structural health monitoring, the magnetostrictive (MS)-tagged fiber-reinforced composites stands out as especially suitable due to: (a) distributed sensory properties, (b) non-contact damage detection, and (c) straightforward manufacturing implementation. Experimental data and mathematical modeling of a MS-tagged fiber reinforced composite beam under bending (flexural) loading are presented. A brief review of the state of the art identifies previous work on axially loaded MS composites, but finds no previous work on bending. Description of bending beam design and fabrication is followed by theoretical analysis and by the description of the experimental set-up and equipment used. Several analysis models were used. Test data, with and without applying magnetic bias field between loading cycles, is presented and results are discussed. Numerical values for the stress and strain versus magnetic flux density coefficients are given for both annealed and non-annealed cases. Piezomagnetic coefficients for the MS composite are calculated. The correlation between the results developed in the present paper for bending and previously published results for axial loading is found to be within 10% after correction factors depending on the quantity of the MS material.