Embedded Sensory Particles May Better Detect Damage In Aircraft And Spacecraft
Hartl and Karaman propose to use a composite they are developing in which single and polycrystalline magnetic shape memory alloy (SMA) sensory particles are embedded into aluminum alloys to detect cracks with the magnetic signals that emanate from these particles near the crack damage zone. Magnetic signature measurement is accurate and avoids false positives during operation.
SMAs are unique because the responses they exhibit are due to temperature, stress or magnetic field-induced phase transformation. As a crack forms, particles in the vicinity of the damage will transform between two different material phases. Both are solid, but they exhibit different properties so that the change from one to another can be detected using a number of different methods depending on the material.
The materials enabling this novel technology are a special sub-class of meta-magnetic SMAs (MSMAs), whose magnetic properties drastically change when they undergo a stress induced solid-solid martensitic transformation. The small size and wide distribution of the particles throughout the material should permit damage detection much earlier than existing technologies, leading to improved reliability and reduced costs.
A study will be carried out using models of embedded sensory particles, each model having varying particle sizes and densities. Model simulations will be used to determine which size and density configurations maximize transformation signal strength, while minimizing the effect that the particles have on overall performance of the material.
The focus of this research project will be on tailoring and fabricating specific sensory particle alloys and addressing the fabrication challenges for embedding these particles in aluminum alloys. Experiments will be performed to detect and interpret magnetic signals, developing an accurate model of the MSMA material behavior and designing sensory particle distributions for damage sensing at the component level.
The end goal is the effective magnetic detection of cracks, and the team hopes to demonstrate that phase-transforming sensory particles comprised of alloy systems exhibiting thermal-magnetic-mechanical couplings can be successfully embedded in aluminum components, and can be used to provide magnetic signatures during experiments where damage is introduced into these components.
Hartl says, “By combining the research strengths of my team with that of Ibrahim’s, I have no doubt that some important developments will result from this new support.”
