SBIR-STTR Award

Antech’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. 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. 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. Potential NASA Applications (Limit 1500 characters, approximately 150 words) Antech envisions the proposed enhanced PA-MAE monitoring system being used primarily as a Structural Health Monitoring system for NASA spacecraft and launch vehicles both manned and unmanned to detect/locate/characterize impact damage and age related defects, such as cracks in metallic structures and microcracks, fiber buckling, and fiber breakage in composite materials. With better sensor sensitivity, the system will be efficient, effective, and reliable, and provide real time mission critical information on the status of NASA structures. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) The PA-MAE system could be used on Navy, Coast Guard, and commercial ships as a Structural Health Monitoring system able to monitor the entire hull for cracks and impacts with widely dispersed phased arrays. It could also monitor composite pressure vessels used for transportation of compressed natural gas and hydrogen fuels, above ground storage tanks for leaks, and concrete structures for damage.

The proposed Phase II innovation is the prototype manufacture of an enhanced passive monitoring system that 1) incorporates the same receiving electronics approach that satellite communication hardware uses for improved receiving sensitivity, 2) uses innovative sensor designs that significantly improve measurement sensitivity, and 3) applies wavelet transform image analysis software that automatically identifies wave mode features that are typically lost in conventional signal analysis. This approach results in better source identification and location for the complex signals encountered in structural health monitoring. To increase the sensitivity of the sensors while managing the program risk, a single element approach that uses the sensor resonance and matching networks to increase sensitivity, while still maintaining high fidelity mode identification analysis via the image software development, will be used. With the noise levels of commercially available electronic components in the nanovolt to microvolt range, dynamic range gains of up to 30 dB over conventional designs will be achieved in the electronic design and manufacture of the components. This is a very high bang-for-the-buck approach to gain a huge sensitivity leap for better flaw growth detection. It increases the dynamic range which reduces signal distortion due to amplifier and analog-to-digital converter saturation caused by the wide range of amplitudes encountered in passive monitoring, while lowering the voltage noise level to increase sensitivity. The signal analysis software uses wavelet transforms to turn raw 2D signals into 3D images that are rich in the information they contain. Analyzing images in 3D space for pertinent information opens a vast array of analyses that greatly enhance the feedback to the user of the technology in a fully automated manner that can be almost instantaneous in communicating the source of energy release events in the structure being monitored. Potential NASA Applications (Limit 1500 characters, approximately 150 words): Passive SHM of payloads in transit from point of manufacture to launchpad to space to final station whether orbiting or operating on a moon or planet where constraints on power, weight, and footprint are paramount. Monitoring of space vehicles and orbiting stations for space debris impacts. SHM of composite pressure vessels, composite materials, and other large metallic and composite structures, and Lunar Gateway. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): Monitoring of Navy, Coast Guard, and Commercial Shipping hull structures for crack propagation at sea, Navy submarine pressure vessels, and composite HP air tanks. Monitoring Navy and commercial aircraft fuselage, wings, and large structural elements for crack propagation in flight. Petrochemical Ind. – Leak detection in piping and aboveground storage tanks. Duration: 24