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Dynamics Based Damage Detection of Plate-Type Structures

Lu, Kan
http://rave.ohiolink.edu/etdc/view?acc_num=akron1133818717

Abstract Details

2005, Master of Science, University of Akron, Civil Engineering.
There is a pressing need to develop effective techniques for structural health monitoring (SHM), so that the safety and integrity of the structures can be improved. The main objective of this study is to evaluate the dynamics-based damage detection techniques for the plate-type structures using smart piezoelectric materials and modern instrumentation like Scanning Laser Vibrometer (SLV). The study comprises of testing an E-glass/epoxy composite plate with an embedded delamination and an aluminum plate with a saw-cut crack using two different actuator-sensor systems: (1) SLV with PZT (lead-zirconate-titanate) actuators (PZT-SLV), and (2) Polyvinylidenefluoride (PVDF) sensors with PZT actuators (PZT-PVDF). The numerical finite element (FE) analysis is also performed to complement the damage detection. Three relatively new damage detection algorithms (i.e., Simplified Gapped Smoothing Method (GSM), Generalized Fractal Dimension (GFD), and Strain Energy Method (SEM)) are employed to analyze the experimental and numerical mode shape data and Uniform Load Surface (ULS). From the damage detection outcomes, it is observed that the PZT-SLV system proves to be more convenient and effective, and it is capable of scanning a large number of points over the entire plate specimens; while the PZT-PVDF system, in which the curvature mode shapes are directly acquired, exhibits good sensitivity to damage. The damage detection algorithms like the GSM, GFD and SEM based on the utilization of three consecutive mode curvatures (modes 3 to 5) and resulting ULS curvature successfully identify the presence and location of delamination in the composite plate; however, they do not show much success in locating the saw-cut crack in the aluminum plate with the same mode curvatures. Using the transverse bending dominated modes (e.g., modes 6 and 12), the above damage detection algorithms are capable of locating the saw-cut crack in the aluminum plate. Due to refined analysis of FE approach, all the algorithms are viable of detecting the damage using the FE data. The add-on advantage of the above three damage detection algorithms is that the data from the healthy plates are not required as the reference, thus simplifying the detection process. The GSM and SEM seem to provide better damage detection than the GFD. The employment of the combined static-dynamic experimental technique apparently increases the effect of damage (e.g., the delamination), and the application of GSM, GFD and SEM further facilitate to quantify the magnifying effect. In conclusion, dynamic response measurement using two proposed sensor systems (PZT-SLV and PZT-PVDF) and related implementation of damage detection algorithms for damage evaluation of plate-type structures are demonstrated in this study. The successful implementations of the damage detection techniques, such as GSM, GFD, SEM, ULS, and the combined static-dynamic experimental technique, validate the effectiveness and accuracy of the two sensor systems in damage detection of plate-type structures.
Pizhong Qiao (Advisor)
189 p.
Dynamic response; Delamination; PLates; Scanning Laser Vibrometer; Polyvinylidenefluoride sensors; damage detection algorithms; Uniform load surface

Recommended Citations

Citations

  • Lu, K. (2005). Dynamics Based Damage Detection of Plate-Type Structures [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1133818717

    APA Style (7th edition)

  • Lu, Kan. Dynamics Based Damage Detection of Plate-Type Structures. 2005. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1133818717.

    MLA Style (8th edition)

  • Lu, Kan. "Dynamics Based Damage Detection of Plate-Type Structures." Master's thesis, University of Akron, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1133818717

    Chicago Manual of Style (17th edition)

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