Improved Passive Phased Array Sensor System for Enhanced Health Monitoring of Large Complex Structures

Antechrsquo;s team will develop a concept for a Phased Array Modal Acoustic Emission (PA-MAE) passive monitoring system for large complex structures that provides at least a tenfold increase in sensor sensitivity thereby greatly improving the efficiency, precision, and reliability of the system. Our PA-MAE concept promises a revolutionary assessment capability that operates in real time to detect, locate, and evaluate major structural impacts and age related defects in all materials much more effectively than current health monitoring capabilities. Our proposal is founded on the same technology NASA used on the Space Shuttles after the Columbia incident to detect impacts during launch.The gain in sensor sensitivity is achieved by stacking broadband piezoelectric crystal elements into a single sensor housing and then creating a phased array of the stacked elements at a single monitoring site. Stacking the sensors will increase signal amplitudes by summing outputs at the same detection location, while using a phased array and summing signals from closely spaced stacks will increase signal amplitudes via the phasing.nbsp;Using both the stacks and the phased signals provides a 30 to 40 dB gain in sensitivity with no electronic gain required, thus significantly reducing electronic noise levels. In addition, the system will utilize a 24 bit analog-to-digital converter instead of the normal 16 bit converter to provide a larger dynamic range.nbsp; This will eliminate the signal saturation due to extraneous noise signals that saturates current hardware leading to signal distortion and missed defect growth signals.This novel approach results in a sensor array that is based on proven technology, monitors the full frequency spectrum of guided waves propagating as a result of damaging events, and detects and locates damage and cracks over very large areas of NASA structures more accurately, efficiently, and reliably than current monitoring systems.