Damage detection using self-sensing concepts

Self-sensing refers to the structural material sensing itself. Real-time self-sensing of damage in carbon fibre polymer-matrix composites by electrical resistance measurement is reviewed. The resistance changes irreversibly upon damage, as shown for damage inflicted by flexure, tension, fatigue, and impact. Delamination increases the through-thickness resistance. Fibre breakage increases the longitudinal resistance. The oblique resistance, as measured at an angle between the longitudinal and through-thickness directions, is particularly sensitive. Minor flexural damage causes the oblique resistance in the unloaded state to decrease. Current spreading enables the sensing of localized damage by measurement away from the damage, though it reduces the spatial resolution of the sensing. The resistance method is more sensitive than the potential method. Two-dimensional sensing is complicated by the anisotropic spreading of the current. Thermal damage and through-thickness (fastening) compression effect are indicated by the contact resistivity of the interlaminar interface. The through-thickness compression effect is alternately indicated by the longitudinal volume resistivity. The condition of a composite fastening joint is indicated by the contact resistivity of the joint interface. JAERO203