Active Microwave Thermography (AMT) is based on the integration of microwave and thermographic nondestructive testing (NDT), which utilizes a microwave heat excitation for subsequent thermal measurements. AMT has strong potential for controlled, rapid, and effective inspection of targeted (surface or volumetric) regions of rehabilitated concrete infrastructure. By combining the benefits of multiple NDT techniques, unique features of multiple methods can be brought together to achieve new results that one method alone cannot achieve. A significant advantage to the integration of these techniques lies in the ability to capitalize on microwave signal properties to achieve focused and localized heating. The outcomes of this research will result in a new NDT method with broad-reaching applications for inspection of aging infrastructure, which has direct benefits to society through cost-savings and general safety of the public. In addition, this research establishes an approach for simulation and experimental aspects that will serve as a solid developmental platform for expansion of AMT to other fields such as medical, aerospace, and security. Research opportunities within this project will be offered to underrepresented (minority/female high school through graduate) students. Further, this work will have a significant impact on the content of several undergraduate and graduate courses taught in the electrical and computer engineering department, the civil, architectural, and environmental engineering department, and the chemistry department at Missouri University of Science and Technology.
This work aims to develop the general science behind a unique nondestructive testing (NDT) method for controlled, rapid, and effective inspection of targeted (volumetric) regions of a structure through the integration of microwave NDT and thermography, referred to as Active Microwave Thermography (AMT). A significant advantage to merging these techniques lies in the ability to capitalize on the strengths of microwave NDT and thermography while improving their limitations. A key benefit to utilizing microwave energy as a heat source is the potential for controlled and targeted heating, thereby improving the efficacy of thermography. The tasks proposed in this project will be conducted through multi-physics based microwave and thermal simulations and will be subsequently verified with measurements. A materials characterization effort will be conducted to characterize the materials used in rehabilitated concrete structures from an electromagnetics point-of-view. This information will be invaluable for other applications where such materials are utilized. Moreover, as part of the material characterization effort, this work capitalizes on microwave-induced heating to determine information about electric dipole moments. This study will also provide information necessary to build predictive models for how a material will physically respond to microwave heating and eventually predetermine thermal signatures for healthy and defective samples. Further, these tasks will address critical issues including the effectiveness and optimization of microwave heating and the detection sensitivity of AMT to flaws/defects. Moreover, current literature states that modulated lock-in methods are not possible for AMT due to the interaction between the microwave energy and thermal camera hardware. However, AMT systems can be designed to reduce the electromagnetic interference with the thermal camera, thereby alleviating this limitation and opening the door for a more successful utilization of this technique. Additionally, this study will explore the potential for advanced signal processing techniques that utilize microwave-specific attributes such as polarization control and patterned heating that will lead to improved defect detection and characterization capabilities. Overall, the project outcomes will not only result in a new inspection method for the transportation and infrastructure industries, but also a development platform for applications of AMT in other important industries such as medical, aerospace, and security.
