Detection Sensitivity Analysis for a Potential Drop (PD) Structural Health Monitoring (SHM) System

Abstract

The paper presents a detection sensitivity analysis for a novel approach to monitoring fatigue crack growth. A carbon nanotube (CNT) sensor was used based on a potential drop (PD) damage detection strategy. Resistive CNT film was laminated between impermeable membranes to create a durable crack gauge that can resist high strain levels, high temperatures and submersion in water. Any crack growth below the sensor would disrupt the CNT electrical entanglement, therefore increasing the network resistance. As opposed to traditional crack gauges with discretized output based on broken copper traces, the CNT crack gauge provides for a continuous range of output, with resistance change proportional to the square of the crack length. The purpose of the present study was to evaluate the sensitivity of this CNT sensor to damage size using statistical approaches recently developed specifically to be applied to Structural Health Monitoring (SHM), including the Length at Detection (LaD) and REpeated Measured Random Effects Model (REM2) techniques.