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Baseline-free Damage Identification for Plate-like Structures using a Delay and Sum Beamforming Algorithm

Thakur, Ashwani
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1637156049283095

Abstract Details

2021, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
The presence of damage can significantly decrease the performance of a structure and lead to potential repairs, downtimes, and failures. Therefore, it is important and desirable to identify the damage at an early stage. This work proposes a baseline-free damage identification method using an acoustic beamforming approach. This approach excites a plate-like structure using an active acoustic source and measures sound radiation of the structure in the form of sound pressure using a microphone array. The measured sound pressure is processed using a delay and sum beamforming (DASB) algorithm to identify the existence and spatial location of the damage. In the algorithm, the damage is considered as a dominant point sound source, assuming the sound pressure from the damage has a much higher magnitude than that from intact areas of the structure. The existence of damage is identified based on an acoustic damage index, and its location is identified as the centroid of a non-zero area of clustered auxiliary binary damage index. Numerical and experimental studies were conducted to investigate the effectiveness and robustness of the proposed method. In the numerical study, a vibro-acoustic finite element model is constructed: a metal box is modeled with damage in the form of a through-thickness hole on its front plate and an active monopole sound source is placed inside the box to generate acoustic excitation. Parametric studies are performed to understand the effects of the damage size and location, microphone array arrangement, excitation frequency, and distance between the box and microphone array, on damage identification results by the proposed method. The robustness of the proposed method is also studied for measurement errors of sound pressure and position estimation errors of a microphone array and scan points on the structure. In the experimental study, a vibro-acoustic test setup was established in a hemi-anechoic chamber. A metal box with a front plate undergoing six damage scenarios was prepared, a tweeter was attached to the box to generate acoustic excitation. The damage scenarios consisted of circular through-thickness holes of different diameters and locations. A rectangular microphone array was set up for sound pressure measurements. The effectiveness of the proposed method for the six damage scenarios was investigated with multiple excitation frequencies, distances between the damaged plate and microphone array, and input voltages. Both the numerical and experimental studies validated the effectiveness and robustness of the proposed method.
Yongfeng Xu, Ph.D. (Committee Chair)
David Thompson (Committee Member)
Jay Kim, Ph.D. (Committee Member)
65 p.
Mechanical Engineering
Damage detection; plate structures; active sound source; microphone array; acoustic beamforming algorithm

Recommended Citations

Citations

  • Thakur, A. (2021). Baseline-free Damage Identification for Plate-like Structures using a Delay and Sum Beamforming Algorithm [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1637156049283095

    APA Style (7th edition)

  • Thakur, Ashwani. Baseline-free Damage Identification for Plate-like Structures using a Delay and Sum Beamforming Algorithm. 2021. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1637156049283095.

    MLA Style (8th edition)

  • Thakur, Ashwani. "Baseline-free Damage Identification for Plate-like Structures using a Delay and Sum Beamforming Algorithm." Master's thesis, University of Cincinnati, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1637156049283095

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.