Research on Repolarization Characteristic of PVDF Strain Sensor Used in Smart Tires

Piezoelectric polyvinylidene fluoride (PVDF) film sensors embedded in a tire can make the tire have a sense of tactile. Thus, PVDF strain sensors play an important role in smart tires. However, temperature tolerance of PVDF is a key issue limiting its application in smart tire as the embedding process needs high temperature vulcanization. This paper proposes a film repolarization method to treat PVDF film materials after high temperature vulcanization, which can be implemented to apply in smart tire. Variation in piezoelectric properties and its changing mechanism of PVDF film are analyzed with the methods of X-Ray Diffraction Spectroscopy (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Vulcanization process that PVDF film sensors undergo in tire applications are simulated. Furthermore, properties of the PVDF sensors with different process stages are simulated based on finite element model. An experimental platform of the PVDF sensors is set up and the drop rod experiments are conducted. Results verify the performance improvement of the repolarization strategy on embedded PVDF sensors. The effectiveness of the repolarization in the PVDF film shows a great significance for the application of strain sensors in smart tire.