Abstract
Composite materials have been widely used for primary structures of aircraft, and a rapid diagnosis method for large composite structures like aircraft components is required. In this study, a new inspection method using a lightning protection shield (LPS) as a load sensor and its wiring is proposed. Proposed load sensor is composed of copper plate used for LPS (upper layer), circuits (lower layer) and silicone rubber sheet used as support material between these two layers. The circuit consists of copper wires which are arranged in the direction of x-axis and which are arranged in the direction of y-axis. When an aircraft structure is impacted, copper plate of the sensor (upper layer) makes contact with wires of lower layer. Therefore a new electrical path occurs between the copper plate and circuit at the impacted point only while the colliding object is pressing the copper layer. A voltage gradient is applied to copper wires by Nichrome wire connected perpendicularly to the copper wires of each direction. The coordinates of the impact point can be identified by the touchpad techniques. To verily the practicability of the proposed sensor, impact load tests were conducted with the proposed sensor of 25mm×225mm and impacted position was identified within an error of less than 10.3mm.
