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Full text release has been delayed at the author's request until April 25, 2026

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Photogrammetry-based Non-Contact Damage Detection for Plate-like Structures

Ramesh, Karthik
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712914952563823

Abstract Details

2024, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Vibration based methods for Structural Health Monitoring (SHM) have become increasingly popular over the last few decades. In this field, non-contact measurement techniques have garnered a lot of attention due to its capacity to provide spatially dense full-field measurements. One such method is photogrammetry, which works on the technique of tracking an object or feature on the surface of a structure. This study proposes a fully non-contact method for estimating the Operational Deflection Shape (ODS) of a plate-like structure based on detecting and tracking a laser projected feature which can provide a dense measurement grid and has no permanent effect on the surface of the structure being measured. It has been long established that any local damage to a structure defined by a loss of stiffness causes local anomalies in the structure's ODS, which can be localized by taking the second derivative of the ODS, commonly known as its curvature. In this study, a damage index is formulated for plate-like structures using higher order derivatives, namely the second, fourth and sixth derivatives, with different orders of accuracy and is shown to successfully identify damage with no knowledge of the structure's undamaged state. The derivatives are computed using the central finite difference scheme. Both experimental and numerical studies are conducted to test the robustness and efficacy of the proposed index. In the numerical investigations, a Finite Element Model (FEM) is used to simulate and extract the natural frequencies and mode shapes of a plate-like structure under free-free boundary conditions. The robustness of the proposed damage index is studied for varying levels of measurement errors, simulated by adding white Gaussian noise. The effects of different parameters like the location and size of the damage are also studied. In the experimental investigation, a damaged steel plate is acoustically excited using an electric speaker at a frequency very close to one of its natural frequencies. The displacements of the plate are measured by tracking the movement of the laser feature projected onto the surface of the plate. The displacements of the projected feature are tracked by processing images captured using a high-speed camera. From the captured displacements, the ODS of the entire structure is estimated. In this study, 2 different ODSs of the damaged plate are experimentally measured and used for damage detection. Further, a spectral folding technique is applied to estimate ODSs when the displacements are sampled at a rate below the Nyquist frequency. The damage index is then applied on all the measured ODSs to successfully localize damage on the structure.
Yongfeng Xu, Ph.D. (Committee Chair)
Allyn Phillips, Ph.D. (Committee Member)
Jay Kim, Ph.D. (Committee Member)
97 p.
Mechanical Engineering
Non-contact measurement; Operational deflection shape; Damage detection; Photogrammetry

Recommended Citations

Citations

  • Ramesh, K. (2024). Photogrammetry-based Non-Contact Damage Detection for Plate-like Structures [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712914952563823

    APA Style (7th edition)

  • Ramesh, Karthik. Photogrammetry-based Non-Contact Damage Detection for Plate-like Structures. 2024. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712914952563823.

    MLA Style (8th edition)

  • Ramesh, Karthik. "Photogrammetry-based Non-Contact Damage Detection for Plate-like Structures." Master's thesis, University of Cincinnati, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712914952563823

    Chicago Manual of Style (17th edition)

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© 2024, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.