Optimum Sensing Configurations for Delamination Identification Using Electrical Resistance Tomography

Damage in Carbon Fiber Reinforced Polymer (CFRP) composites due to cracking modifies the internal electrical conductivity of the composite material. Electrical Resistance Tomography (ERT) is a non-destructive evaluation (NDE) technique that takes advantage of electrical conductivity changes to determine the extent of damage. Implementation of ERT for damage identification in CFRP composites requires the optimal selection of the sensing sites for accurate results. This selection depends on the measuring scheme used. The present work uses an effective independence (EI) measure for selecting the minimum set of measurements among all possible for ERT damage identification using three measuring schemes: two-probe, four-probe and multi-probe. The electrical potential field in two CFRP laminate layups with 14 electrodes is calculated using finite element analyses (FEA) for a set of specified delamination cases that span the space of possible damage states. The measuring schemes are used considering the cases of 14 electrodes distributed on both sides and 7 electrodes are on one side of the laminate, for each layup. The effectiveness of EI reduction is demonstrated by comparing the inverse identification results of delamination cases for the full and the reduced sets using the measuring schemes and electrode sets. This work shows that the EI measure optimally reduces electrode and electrode combinations in ERT based damage identification for different measuring schemes used.