Health Monitoring of Bolt Looseness in Timber Structures Using PZT-Enabled Time-Reversal Method

<table class="figure-group"><tr class="fig-image" id="a"><td><object data="https://static.hindawi.com/articles/js/volume-2019/2801638/figures/2801638.fig.008a.svgz" name="2801638.fig.008a" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(a) </b>The focused signal in 10 N·m</td></tr><tr class="fig-image" id="b"><td><object data="https://static.hindawi.com/articles/js/volume-2019/2801638/figures/2801638.fig.008b.svgz" name="2801638.fig.008b" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(b) </b>The focused signal in 20 N·m</td></tr><tr class="fig-image" id="c"><td><object data="https://static.hindawi.com/articles/js/volume-2019/2801638/figures/2801638.fig.008c.svgz" name="2801638.fig.008c" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(c) </b>The focused signal in 30 N·m</td></tr><tr class="fig-image" id="d"><td><object data="https://static.hindawi.com/articles/js/volume-2019/2801638/figures/2801638.fig.008d.svgz" name="2801638.fig.008d" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(d) </b>The focused signal in 40 N·m</td></tr></table>

<div>The focused signal with a preload of 10–40 N·m.</div>

Journal of Sensors

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Figure 8

Figure 8: Health Monitoring of Bolt Looseness in Timber Structures Using PZT-Enabled Time-Reversal Method 