Optimized Structural Health Monitoring System Design for Aviation Structures

Abstract

This paper describes the development and testing of an active-acoustic-structuralhealth- monitoring (SHM) methodology for detection of crack damage that occurs in aircraft structures. The SHM techniques employed measure and evaluate frequency dependent mechanical responses. The responses are from a monitored structure excited by acoustic/vibratory signals injected into the structure at preselected locations. The SHM methodology included the following stages: (1) a design stage, where researchers conducted dynamic-digital simulations, based on a finite element model (FEM) of a subject airframe structure, determining favorable locations on the structure for placement of acoustic actuators and sensors; (2) a baseline testing stage, where test engineers installed acoustic actuators and sensors on an actual helicopter airframe structure in accordance with the design stage findings; then, conduct repetitive frequency-sweep tests collecting acoustic baseline response data; (3) a damaged-structure testing stage, where test engineers induced specific crack damage in the structure, then repeated the tests of the baseline testing stage, acquiring corresponding data for the damaged structure; and, (4) an analysis stage, where the researchers employed statistical-anomaly-detection techniques identifying statistically-significant differences between the baseline data and the damage test data to determine detection rates and localization performance.