CLoVER Transducers for Static and Dynamic Strain Sensing
This paper presents the theoretical formulation and initial experimental investigation of static and dynamic strain sensing using the Composite Long-range Variable-direction Emitting Radar (CLoVER) transducers. CLoVER Transducers are manufactured using the piezoelectric fibers integrated with the interdigitated electrodes with wedge-shaped sectors arranged in a circular way. A coupled-field analytical model was developed based on the piezoelectricity constitutive equations with the consideration of the anisotropic material properties of CLoVER transducers. The analytical formulation was derived under a cylindrical coordinate system for a single CLoVER sector. The influence from the measuring electronic circuit and a non-uniform strain field were considered. The final sensing formulation contained three strain components and six strain gradients. Sensing signals from nine independent CLoVER sectors with different installation orientations were used to compute for the nine unknown strain related components. Two operational conditions were discussed: (1) static strain sensing and (2) dynamic strain sensing. To validate our analytical model and demonstrate the strain sensing capability of the CLoVER transducers, comparative experiments with conventional strain gauges were conducted on a fix-free aluminum plate. Dynamic strain sensing performance of the CLoVER transducer and the strain gauges were compared. After the calibration, the measurement linearity was examined. The piezoelectric responses from the CLoVER sectors were compared with the analytical prediction.
