Experimental validation of a piezoelectric measuring chain for monitoring structural dynamics

PolyVinyliDene Fluoride (PVDF) energy harvesters have been observed to possess the ability to detect leak and damage in pipes they are bonded to by monitoring their vibration energy harvested due to fluid flow, measured as open circuit voltage. Consequently, they can be employed as structural health monitoring (SHM) sensors for such applications. To make this energy harvesting based SHM an effective measurement methodology, the harvested energy should be demonstrably passed through a piezoelectric measuring chain and the results obtained should be calibrated appropriately. This paper addresses this problem by designing a custom-made three-channel dual-stage charge amplifier as signal conditioner and validating the measuring chain. The charge amplifier ensures that the voltage generated by the PVDF harvester is measured accurately and remains proportional to the strain responses for the monitored structure and constitutes a part of the piezoelectric measuring chain. A two-stage validation process was employed in this work. The first stage is a general validation exercise serving as a check for measuring chain intrinsic noise and general performance while the second stage is an application-specific validation exercise that serves to estimate the performance of the measuring chain for the target application. The suitability of using the measuring chain for the application of vibration energy harvesting based SHM is demonstrated through the result of this validation process.