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Sensitive Skin Based on pH Sensitive Smart Materials for Crack Detection



Structural Health Monitoring (SHM) is a mature area aiming to detect and diagnose the cracks, deformation and any type of damage in engineering structures such as airplanes, buildings, bridges etc. Crack detection methodologies involve many non-destructive testing and computational methodologies. In general SHM technologies, the symptoms obtained when the crack is occurring is assumed to be sufficient for its detection and diagnosis. However, engineering systems generally are not sufficiently designed to release symptoms for effective detection and diagnosis. The analysis of biological system may lead to hints in designing the engineering systems to resolve the challenges in release of symptoms. This paper proposes a bioinspired design of symptom releasing mechanisms for crack detection and diagnosis. The proposed system bases on combination of skin and nose mechanisms of the biological systems. In the proposed methodology, the structure is painted with two layers: the upper layer creates a pre-defined pH-level for the inner layer, whereas the inner layer is composed of pH sensitive materials. Crack on structure leads to crack in the painting layers as well. The contact of the lower level with air due to the crack on upper level changes the pH level leading to inflation of pH sensitive materials. The inflated materials fills the gap occurred due to crack. The pH sensitive material is nonconductive and it reduces the conductivity of the upper paint layer. The measure of the electric impedance tomography on the upper layer paint is used for crack detection and diagnosis. The effect of non-conductivity leads to increased change on the electric impedance tomography leading to better detection and diagnosis mechanism. The paper presents the details of the proposed smart material based crack detection methodology.

doi: 10.12783/SHM2015/218

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