Dynamics- and Laser-Based Boundary Effect Evaluation Method for Damage Inspection of One- and Two-Dimensional Structures

This paper presents new damage indicators and current capabilities of a dynamics-based Boundary Effect Evaluation Method (BEEM) for damage inspection of large one-and two-dimensional structures. Damage introduces new boundaries to a structure, and influences of boundaries on steady-state high-frequency dynamic response are spatially localized effects. The BEEM is a signal processing method that takes advantage of these localized effects in performing area-by-area extraction of damage-induced boundary effects from steady-state Operational Deflection Shapes (ODSs) to reveal damage locations. Steady-state ODSs of a structure can be measured using a scanning laser vibrometer or any other full-field measurement tool, and the BEEM decomposes an ODS into central and boundary solutions by using a sliding-window least-squares data-fitting technique. Numerical and experimental results show that boundary solutions are excellent damage indicators because of Gibb’s phenomenon, and the central solutions can be used to clearly identify actual boundary conditions. Except for experimental ODSs of the damaged structure the method requires no model or historical data for comparison. Experimental results of many one-and two-dimensional structures validate the high sensitivity and accuracy of BEEM for detection and estimation of multiple small defects in structures.

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