Collision Monitoring of Foreign Object on CFRP Laminate Utilizing Electrostatic Induction

In this paper, a collision monitoring method utilizing electrostatic induction is proposed, designed, tested, and validated. When a foreign object, which is regarded as a charged body because any object is charged to a greater or lesser extent, approaches and collides with a grounded electric conductive material, an electric current caused by electrostatic induction flows to ground. The electric current is used for collision monitoring in this paper. The principle of the proposed collision monitoring method can be used for any conductive plate, which is in the air or a vacuum. However, the method is particularly aimed at collision monitoring on carbon fiber reinforced polymer (CFRP) structures for reducing the inspection cost by identifying the area where detailed inspection, such as ultrasonic inspection, needs to be conducted. The sensors are composed of the monitored object of a large conductive plate, such as a CFRP laminate, and strip conductors, such as copper tape arrayed in grid. When a foreign object collides with the monitored object, electric currents flowing through the strip conductors are measured and analyzed, and the collision point, angle, and speed of the foreign object are identified using an optimization method. As a result of several experiments, the collision point, angle, and speed are identified with high accuracy (within 5% error except for a specific case).