CAREER: Multi-Physics Transient Holography: A Non-Intrusive Imaging Approach for the Identification of Structural Damage in Mechanical Systems

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This Faculty Early Career Development (CAREER) Program project aims at advancing the state-of-the-art in non-destructive/non-intrusive imaging techniques for structural health monitoring. Structural health monitoring is a highly multidisciplinary area of engineering that investigates advanced sensing systems and data analysis methodologies to assess the integrity of structures. These monitoring systems have the potential to revolutionize the maintenance strategy for transportation systems and infrastructure by allowing frequent or continuous inspections thus ultimately increasing safety and reliability at reduced operating costs. Specifically, enabling the transition to a condition-based maintenance strategy is key to ensure the long-term sustainability of our nation infrastructures. The research explores a new concept of imaging technology that leverages and combines multiple physical principles, ranging from the mechanical to the thermal to the electromagnetic fields, yielding a highly sensitive approach able to achieve performance beyond current imaging techniques. The project will investigate the fundamental principles of this advanced imaging technology and will demonstrate its effectiveness through laboratory tests. The outcome of this research will benefit the current and future US infrastructure and transportation systems and will lay the foundations for the transition of this technology to other fields, such as medical imaging and material characterization, where highly sensitive and accurate imaging tools are enabling technologies. The approach to be investigated is based on the novel idea of multi-physics transient holography, whereby the coupled electromagnetic-thermo-acoustic response is exploited to probe the structure and detect damage. The tomographic problem, which consists in reconstructing images of the interior properties of an object by using penetrating waves, is cast in a holographic framework in order to achieve unprecedented image resolution and detection performance. The multi-physics approach will provide increased damage sensitivity while allowing a largely reduced sensing network, compared to current technologies. In order to unlock the full potential of the holographic approach, this research will also explore new technologies in areas that are complementary to image reconstruction such as data processing, mathematical modeling, and transducers development. Of particular relevance for the general field of tomographic imaging is the formulation of a new generation of multi-resolution computational models based on adaptive grids and of a novel concept of flexible skin transducer for multi-mode actuation and sensing. Dedicated software and hardware will also support the validation and performance characterization of the imaging technique via laboratory experiments.