Electrical resistance change vs damage state in cracked symmetric laminates: A closed form solution

An analytical solution is developed to assess the stiffness loss in conductive symmetric laminates, caused by the presence of off-axis cracks, as a function of the intrinsic electrical resistance change. In order to achieve this ambitious aim, initially the attention is focused on the electrical problem, and a closed form solution is developed which allows the electrical resistance of the laminate to be estimated starting from the density of transverse cracks. Such an expression is later inverted and used in combination with a new analytical mechanical model suitable to estimate the stiffness degradation associated to a given crack density. The accuracy of the proposed solutions is verified by comparison to a bulk of FE analyses, also discussing the effect of the most influencing material and geometrical parameters.