Three-Dimensional Laser Scanning Vibrometry as a Visualisation Tool for Structural Health Monitoring Research

Abstract

The application of three-dimensional scanning laser vibrometry for visualising stress wave propagation in a specimen with a non-surface penetrating defect is presented in this paper. The aim of this paper is to demonstrate the use of this measurement technique to achieve a good insight of the propagation of the stress wave over a given region on a test specimen. An investigation into the interaction of the various wave modes with the defect in the structure can be enhanced with this knowledge. The ability to acquire the time series at an array of measurement points in a given region on the structure provide for an excellent means for visualising the propagation of the incident stress and how they interact with the defect present. In addition to the visualisation aspect, the data acquired can also be transformed to assess the modal content of the various wave modes present within the structure. For the purpose of this paper, a flat aluminium test plate with a non-surface penetrating defect will be used. The application of this form of non-contact measurement technique for the stress wave visualisation work will be illustrated. It will be shown that this measurement technique can be used to establish the modal content and the time-development of the incident and the scattered wave modes in the test specimen.