Structural health monitoring of smart carbon-fiber 3D angle-interlock woven composites with double electrical dipole

The quantitative analysis between structural damage and electrical potential change of smart carbon fiber composites is important to structural health monitoring. Here the spatial electrical potential distribution of carbon-fiber three-dimensional (3D) angle-interlock woven (AIW) composites with double electrical dipole under low velocity impact was investigated. X-ray micro-computed tomography (micro-CT) and Ultrasonic C-scans test were utilised to reveal the correlation between damage evolution and the electrical potential variation under multiple impacts. An orthotropic electrical potential function method is established to analyse the spatial electrical potential distribution of 3D AIW composites. It was found bending stiffness decreases and indentation depth increases, individually, due to gradual accumulation of resin crack and interface debonding. Microcracks and local delamination are the main impact damage modes to promote energy dissipation. The compound electrical field induced by electrical current is formed by the mutual cancellation of positive and negative potential values under double electrical dipole. Diamond shaped low potential region (|φ|≤0.5 mV) is formed in the central area of composite plate because of the potential superposition effect. The resistance network in the damage area is destroyed, resulting in higher electrical potential value between two adjacent nodes. The area of diamond shaped low potential region decreases as the indentation depth increases due to multiple impacts. It proves the feasibility of the electrical potential technique in real-time structural self-sensing information on the damage evolution of damage of complex 3D woven composites.