A composite beam integrating an in-situ FPCB sensor membrane with PVDF arrays for modal curvature measurement

This research develops a novel composite beam integrating a flexible printed circuit board (FPCB) sensor membrane with polyvinylidene fluoride (PVDF) arrays for accurately extracting modal curvature in a convenient way, which can be easily used in the potential aerospace applications of in-situ structure damage detection or structure health monitoring. The proposed composite beam structure consists of a metal beam, a FPCB sensor membrane and a periodic array of identical rectangular PVDF films. Specifically, a periodic array of identical rectangular PVDF films is encapsulated in the FPCB sensor membrane, and the FPCB sensor membrane is integrated with the metal beam. Since the lead wire, sensors, the protective layer of sensor and the host beam structure are of one-piece construction in the proposed structure, the proposed structure has the self-sensing function that the discrete curvature of modal shapes of the metal beam can be directly obtained by using the experiment modal analysis (EMA) method and no other sensors. Results show that the proposed structure has good self-sensing performance and can directly extract the modal curvature information without any numerical differential calculation. In addition, the proposed structure restrains surrounding noise and improves the stability of the sensor array signal since the sensor array is encapsulated with the metal beam under the same condition.