Polyvinylidene Fluoride (PVDF), a piezoelectric polymer, is an excellent stress sensor. The objective of this research is to investigate the application of the PVDF sensors for detection of in-plane stress waves in 31 and 32 modes. This was achieved by focusing on aspects of PVDF sensing related to determination of impact force, detection of stress wave propagation, and the stress averaging effect of PVDF sensors.
An experimental method was developed for calculating a proportionality constant between a PVDF sensor's voltage and the impact force, on a solid bar and a hollow beam. This was used to demonstrate that impact force on a structure can be determined using PVDF sensors. Finite element models were also created using the software LS-DYNA to simulate the impact tests. The speed of sound for longitudinal wave propagation in a slender rod was determined experimentally, using two PVDF sensors. The results demonstrate that PVDF sensors can detect high speed stress wave propagation in a structure. Finally, the stress averaging effect of the PVDF sensor was analyzed to investigate its influence on the generated voltage during stress wave detection. Equations modeling the stress averaging effect were derived for periodic applied stress waves and impact-induced stress waves. Numerical simulations were conducted to study the influence of sensor length, applied wave frequency, and structure's material on the stress averaged PVDF response.