Browsing by Author "ohn Birir1, Michael J. Gatari and Prabhu Rajagopal"

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    CHANNEL STRUCTURED METAMATERIALS FOR SUPER RESOLUTION IMAGING
    (ASME, 2019-07-14) ohn Birir1, Michael J. Gatari and Prabhu Rajagopal
    ABSTRACT When inspection is required to be conducted from a remote distance, due for example to safety concerns, guided ultrasonic wave testing technique is the preferred choice. Guided waves are usually low frequency hence are not subjected to much attenuation relative to the bulk waves. As a result, guided waves can travel a longer distance. One of the limitations of guided waves however, is that the low frequency (longer wavelength) used lead to lower resolution capabilities due to the inherent diffraction limits of λ/2 (where λ is wavelength). Guided waves are therefore generally used as screening tools to locate areas of interest. A higher resolution technique is then employed to further investigate and characterize the features of defects in the identified areas. To overcome this challenge of resolution, a technique is proposed that increases the resolution capability of guided waves beyond the diffraction limit. Simulation using commercial finite element software is used to optimize variables involved in the proposed method. The simulation is then validated with experiments. In the present work a resolution of λ/72 is demonstrated experimentally.