Electrical Impedance Spectroscopy for Structural Health Monitoring

Abstract

Structural heath monitoring (SHM) can provide an estimate of the state of damage in a structure, and of the remaining useful life of that structure. The work presented here is an investigation of a proposed new SHM technique for composite structures composed of carbon-fiber-reinforced-polymers (CFRP). Electrical impedance spectroscopy (EIS) is employed to estimate the damage state of the composite. No modification to current CFRP processing methods is required, nor is the proposed technique invasive or destructive. EIS interfaces can be either permanently attached or temporarily connected. We hypothesize that EIS has the potential to be more sensitive and selective for damage detection by using a full complex-plane analysis, considering both impedance magnitude and phase angle. This is in contrast to electrical SHM approaches employing resistance measurement, the real component of impedance, which ignores phase angle and reactance information. In order to test our hypothesis we implemented three different experiments to evaluate the effectiveness of the EIS technique: (1) specimen load sensitivity; (2) specimen damage sensitivity; and (3) specimen fatigue sensitivity. Multiple electrical interrogation paths through the specimen are considered.