Strain sensing capabilities of iron/epoxy composites

Particulate composite materials are very common in industrial applications due to the fact that particulate fillers can provide improved materials, as compared with the unfilled matrix. They can also be synergistic with fiber reinforcement to further improve the system performance. On the other hand, a new approach in structural health monitoring is to exploit the intrinsic properties of the material, such as electrical conductivity, optical properties etc, as sensing parameters. In this paper we present results concerning the strain sensing capabilities of iron/epoxy particulate composites at different percentages varying from 30% to 60% by weight. In particular, we investigate the strain induced alteration of the magnetic resistance (reluctance) of such polymers. The magnetic properties of the iron/epoxy composites have been investigated using a vibrating sample magnetometer at room temperature. For the strain-reluctance measurements, a non-contact sensing probe has been employed. The strain-reluctance relation is found to be linear and strongly dependent on the concentration of iron particles.