|
The key to monitoring structural health and defect detection of materials is the capacity to detect impact waves and their propagation through materials. A sensor must be extremely flexible and have a complex shape to detect impact waves from a certain type of construction. Complex sensors can be produced using direct ink write (DIW). In this article, the DIW approach is used to create a flexible impact wave propagation sensor (IWPS). Barium titanate (BaTiO3, or BTO), a ferroelectric ceramic material, is dispersed in polydimethylsiloxane (PDMS), which not only increases the flexibility of the 3D-printed sensor but also assures a consistent piezoelectric response across the entire sensor. This study investigated the impact load that caused an impact wave in a flexible sensor and its response to the impact load-generated impact wave. On BTO/PDMS stretchable composites, MWCNT (multi-walled carbon nanotube) based electrodes were printed using the DIW's multi-material printing capability. After contact poling of IWPS, 50wt% of BTO in the PDMS matrix produced a piezoelectric coefficient of 20 pC/N. Applying impact loading at the sensor's center caused an impact wave which eventually vanished as it got further away from the applied impact load's origin. The output voltage from several IWPS nodes was measured in order to characterize the propagation of impact waves. Additionally, the particle-wave velocity of a specific material attached to IWPS was calculated in this study using the voltage response time differences at various sensor locations. The particle-wave velocities of stainless steel (SS) and low-density polyethylene (LDPE) were measured using the specially built IWPS and were found to be 5625 m/s and 2000 m/s, respectively. These values are comparable with their theoretical values.
|
