Implementation of Advanced Fiber Optic and Piezoelectric Sensors. Fabrication and211 Laboratory Testing of Piezoelectric Ceramic-Polymer Composite Sensors for Weigh-211 in-Motion Systems

摘要

Weigh-in-motion (WIM) systems might soon replace the conventional techniques used211u001eto enforce weight restrictions for large vehicles on highways. Currently WIM 211u001esystems use a piezoelectric polymer sensor that produces a voltage proportional 211u001eto an applied pressure or load. The biggest disadvantage of the present sensor 211u001etechnology is that the piezoelectric output is not uniform with temperature and 211u001etime, thus leading to large uncertainty in the data collected. On the other hand, 211u001epiezoelectric ceramic materials have a much more stable response over a large 211u001etemperature range. However, they are not used for traffic data sensors because of 211u001etheir inherent brittleness. Piezoelectric ceramic/polymer composites are made 211u001ewith an active piezoelectric ceramic embedded in a flexible non-active epoxy 211u001epolymer. They hold a lot of promise for WIM applications because of their 211u001eflexibility and excellent piezoelectric properties similar to that observed in 211u001ebulk ceramics. In this research project, ceramic/polymer composite strips have 211u001ebeen fabricated for use as piezoelectric sensors for measuring large loads. After 211u001eencapsulating the polymer and composite sensors in elastomeric blocks in aluminum 211u001echannels, the voltage outputs for different loads, loading rates and temperature 211u001econditions have been determined. Also, the composite and polymer sensor 211u001eassemblies are being installed on a test road in order to perform actual 211u001emeasurements.