Energy harvesting array materials with thin piezoelectric plates for traffic data monitoring

This study developed energy harvesting arrays (EHA) composed of multiple piezoelectric elements for traffic monitoring and energy harvesting. The developed EHA was investigated through compression tests to simulate the effects of different vehicle axle loads and speeds. The effect of the number and configuration of piezoelectric elements on piezoelectric response was explored. To quantify the sensitivity of EHA under different loads, the concept of loading utilization efficiency was proposed. The influence of temperature and surface layer type on the output signal of EHA covered with asphalt surface layer was investigated using wheel rolling test. The compression test showed that the response of EHA was affected by both axle load and vehicle speed. The output voltage and loading utilization efficiency increased gradually with the increase of load and load frequency. The response law of EHA provided ideas for monitoring vehicle axle load and speed information. The open-circuit voltage signal decreased as the number of piezoelectric elements in parallel increased. The recommended number of piezoelectric elements was identified. To reduce the impact of temperature and surface covering material on the perceived traffic information, EHA was recommended to be encapsulated with thermal insulation materials for embedment. The open circuit voltage of EHA in the wheel rolling test was found higher than that in the compression test. This difference was further explained by finite element modeling results showing that the polyurethane plate increased the deformation of thin piezoelectric plates. Considering the strength of the piezoelectric response signal, the recommended thickness of polyurethane underlayment was determined.