Eddy Current Inspection-based Damage Detection of Carbon Fiber Reinforced Polymer Composites

Carbon fiber-reinforced polymer composite is used in various industries such as aerospace, automobile, and civil engineering. During the manufacturing stage and end-user stage, carbon fiber composite material is subjected to different kinds of damage, such as delamination, de-bonding, and fiber breakages. Those damages may lead to destroying the application with a life-threatening catastrophe. To identify these kinds of damages, several non-destructive testing (NDT) techniques are used, such as visual, ultrasonic, and optical fiber sensing. However, when considering the initiation and propagation of the damage, microlevel and invisible cracks are crucial. This study used plain weave carbon fiber fabric with an appropriate resin-hardener mixture to make carbon fiber-reinforced composite sheets by hand layer-up process. Subsequently, the samples were subjected to drop weight impact tests with 0.6 j, 1.2 j, 3.0 j, 6.0 j, and hammer impact tests respectively. By using an Ectane-2 eddy current inspection equipment, both sides of the carbon fiber samples were scanned before and after the impact damage. The defect’s location could be seen on the c-scan plane, while the crack propagation could be seen on the impedance plane of the Ectane-2-magnify software screen. Variations in voltage showed an irregular pattern on the impedance plane because of the damage to the carbon fiber strips that affected the electrical conductivity of the composite. The eddy current inspection method is capable of identifying the damage location and propagation of plain weave carbon fiber-reinforced polymer composites. In the future, fiber weaves such as twill and unidirectional need to be investigated.