Impedance Method Application for Multi-Layer Structure Testing

Multi-layer materials and structures are widely used in the modern aircraft industry. The main defect of these structures is delamination. The most appropriate method for detection of such kind flaws is the impedance testing method. This research is devoted to the features of the impedance method for multi-layer panel testing. The theoretical and experimental investigations of mechanical impedance are presented for honeycomb panels. The theoretical investigation provided the analytic expression, which enabled us to determine object parameters such as honeycomb density and thickness, covering thickness and cylindrical rigidity on a test result. The assembly of a combined probe was proposed for experimental investigations of mechanical impedance. An amplitude of the output signal of this probe is depended on the testing object mechanical impedance and flexibility of contact area. Numerical simulation results demonstrate the influence of the object parameters on the effectiveness of the defect detection in honeycomb structure.