OS09W0223 Cure monitoring of composite laminate by piezoelectric ceramics having different dimensions

Abstract

The piezoelectric ceramics with different dimensions are embedded into the composite laminates. The impedance of the piezoelectric are measured by a LCR meter in the autoclave processing. The impedance of the piezoelectric ceramics at non-resonant frequencies is adopted as the cure index. The piezoelectric ceramics have strong temperature dependency. The temperature dependency is corrected by using a dummy piezoelectric ceramics. A dielectric sensor is also embedded in the composite laminate as a reference sensor for the degree of cure. The change in corrected impedance at non-resonant frequency shows good correspondence with change in the log ion viscosity which is measured by the dielectric cure monitoring sensor. At the cooling stage, the changes in the impedance of the piezoelectric ceramics depend on the dimension of the piezoelectric. A finite element method is used for analyzing the deformations of the piezoelectric ceramics in the composite laminate at the cooling stage. The changes of the impedance of the piezoelectric ceramics are dominated by the deformation of polarizing direction.