U.S.-Germany Cooperative Research on the Optimal Generation of Elastic Waves in Structures

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This award supports Professor Fu-Kuo Chang and three graduate students from Stanford University to collaborate in mechanical engineering research with Professor Peter Hagedorn and his colleagues and students of the Mechanics Institute of the Technische Hochschule of Darmstadt, Germany. They are studying ultrasonic elastic wave propagation in a structure, where the waves are generated by piezoelectrics (PZT) built into the structure. The U.S. team uses PZT-generated waves to detect damage in functioning structures made of composite materials. The German team is particularly interested in the propagation of such waves as an aspect of the design of advanced ultrasound motors. The cooperating groups will be involved both in experiments using surface-mounted and embedded piezoceramics and in developing the analytical models of these systems. Because of the complementarity of their interests and approaches, both groups should benefit from this coordinated joint research. Early detection of service-induced damage in structures such as airplanes and bridges plays an essential role in prolonging the lifespan of the structures and in providing safe use of the structures. Clearly damage detection techniques must be non-destructive and ideally they should be convenient to perform on-site during routine maintenance. Ultrasonic wave generation is a promising new approach to this diagnostic process. The results of the proposed cooperative research will improve fundamental understanding of piezo-induced ultrasound propagation, and it will provide the basis for tailoring the production of ultrasonic waves for specific applications by means of controlling the piezo electrics.