Publication: Simulation-guided optimization and experimental validation of a new end cap for tire strain piezoelectric energy harvesters
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Date
2024-09-01
Authors
Alnajati Ibrahim, Ali Hameed
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Abstract
Vehicle accidents are often caused by tire-related issues, particularly improper
tire pressure. To address this, many countries mandate the installation of battery powered Tire Pressure Monitoring Systems (TPMS). Nonetheless, concerns over the
environmental and safety impacts of batteries have led to research into sustainable
energy sources. Piezoelectric energy harvesters, particularly those utilizing PZT-5X,
have emerged as promising alternatives. The primary objective of this study is to
design and optimize a supporting aluminum end-cap structure to enhance the
functionality of PZT-5X for inner tire energy harvesting applications. The study
comprises three main stages: development, optimization, and experimental
investigation. The development process involves analyzing tire models using
ABAQUS software to identify crucial strain distribution patterns and numerically
constructing the harvester structure using COMSOL Multiphysics software. Findings
from the development stage revealed a maximum tire deflection of 16.71 mm for a tire
size of 175/65 R14, with corresponding tire footprint dimensions of 53.62 mm × 50.20
mm. The initial energy generated by the single end-cap harvester (M1) is 32.64 µJ/rev,
while for the dual end-cap harvester (M2), it is 11.66 µJ/rev. Meanwhile, findings from
the pre-optimization phase identified PZT-5X as the most efficient material, with an
optimal thickness of 2 mm and an ideal end-cap rotation angle (Θ) of 5º. Transitioning
to the optimization stage, a Taguchi L9 plan and Analysis of Variance (ANOVA) are
employed. The optimal combination of geometrical parameters was determined to be
11 for end-cap height (hd), 1 for end-cap thickness (ts), and 3 for the adhered length of PZT-5X (Alp). As a result, the optimized harvester (M3) produced an energy output
of 5.44 mJ/rev and 138 mW max power at 3 MΩ and a vehicle speed of 80 km/h. The
experimental work commences with strain measurements using three strain sensors.
At speeds of 20, 40, and 80 km/h, the strain values remained consistent. In other words,
maximum strain occurs at the tire footprint and is not affected by vehicular speed, as
confirmed during numerical analysis. Additionally, three (M3) harvesters were
mounted inside a traveling tire with identical conditions. The results revealed that
changing vehicle speeds do not affect the voltage output. However, it does alter the
frequency of that voltage, enabling faster charging of capacitors when the speed
increases. The accumulated energy for the (M3) ranged from 24.04 mJ to 28.47 mJ,
with a power range from 65.52 mW to 67.54 mW at a 3 kΩ resistance and 80 km/h
vehicle speed. Based on a 30 km road test, the electric lifespan ranged from 5,300 km
to 8,250 km.