A Multifunctional Piezo and Temperature Sensor for Process and Structural Health Monitoring of CFRP Structures Made by Resin Transfer Molding

Abstract

Within this paper, the authors present a novel multifunctional piezo – temperature sensor concept for flow front, cure and structural health monitoring of composite parts. The multifunctional sensor is made of piezo disc in series to a Pt100 temperature sensor used a shunt resistor. In order to measure the impedance of the Piezo a signal generator is connected to the ground electrode of the piezo and the PT100 temperature sensor. The current through the piezo is measured via the Pt100. For actuation, a frequency modulated chirp signal is used and the response voltage over the PT100 sensor is measured. Out of the FFT of the voltage response, the impedance of the piezo sensor can be determined. The developed sensor concept offers several advantages. Only one data acquisition unit for process and SHM is required. The time resolution of cure monitoring can be drastically reduced. The integration of a Pt100 as shunt resistor allows the measurement of the temperature during the manufacturing and usage of the part, where the knowledge of the temperature distribution can be used for effective temperature compensation techniques during SHM with guided waves.