Structural Health Monitoring Using Smart Sensors - ideals ...

EXPERIMENTAL VERIFICATION
Chapter 8
This chapter provides experimental verification of the SHM framework developed in
this research. The SHM framework employing the DCS for SHM was realized on
networks of Imote2s in Chapter 7. Numerical operations of the SHM system were
numerically examined in a component-by-component manner by injecting acceleration
response data to the network of Imote2s and processing the data. The system has been
shown to be capable of processing acceleration data and localizing damage.
The experimental verification of the proposed SHM framework uses acceleration
response data measured by networks of Imote2s. Acceleration measurements and the
subsequent data processing are performed before and after an element of the truss is
replaced with a thinner element having a 52.7 percent cross-section reduction. The
replaced element is detected by cluster head Imote2s. The experiment is repeated multiple
times to assess reproducibility. Also, the experiment is repeated by replacing a different
structural element to see the damage detection capability of the system in various
elements. In this way, the ability of the proposed framework to localize damage is
experimentally verified (Spencer & Nagayama, 2006).
8.1 Experimental setup
The SHM framework is experimentally verified on networks of Imote2s using the
5.6m-long, three-dimensional truss structure discussed in Chapter 7. The truss and the
structural node IDs and element IDs are shown again in Figures 8.1 and 8.2. The shaker is
attached at node 17 and excites the truss with a band-limited white noise.
The Imote2s are installed on the truss using plastic fixtures (see Figure 8.3). The
fixture has two walls, each of which has two threaded holes. A set-screw is inserted into
Figure 8.1. The Imote2 and plastic case.
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