A Multi-Purpose Sensor for Composite Laminates Based on a Piezo-Electric Film

Abstract

In this study, a multi-purpose sensor for composite laminates is devel oped. The sensor is based on a piezo-electric film. A specialty charge amplifier was devel oped for signal conditioning for long time duration measurements. Experiments were con ducted to show the utility of the sensor for static and dynamic strain measurement. By effectively isolating the piezo film for unidirectional strain, a method was developed to utilize the piezo sensor for general, in-plane strain sensing, regardless of the constitutive properties of the laminate. Non-destructive evaluation in through-transmission and pulse- echo modes were shown to be effective for measuring and quantifying damage in lami nated structures. Using the piezo film as a sensor to detect impact, it was shown that an "event" as well as the onset of damage can be accurately measured. With standard acoustic emission equipment, the piezo film proved to be an effective direct substitution for typical piezo-crystals at a fraction of the cost and weight for acoustic emission monitoring in ad vanced composite laminates. The onset of damage, as well as damage location were ac curately measured. The preliminary results indicate that the sensor is quite versatile, inex pensive and sensitive for a variety of sensing applications in advanced composite laminates. In particular, the electronics needed for signal conditioning are much less elab orate than typical sensors such as strain gages, piezoceramic sensors, thermocouples, etc.

A simple sensor model for THUNDER actuators

“…The error in that case was very small for low resistance and increased to about 20% over the range measured. A charge amplifier [21] would have been better to use in this type of situation since it eliminates the effects of the impedance of the scope. The maximum power measurements varied from the model by about 14-20% depending on the frequency.…”

Design of thin-film polyvinylidene fluoride sensor rosettes for isolation of various strain components

“…The method proposed by Matsumoto et al (2004) necessitates two exact host structures with different sensor configurations, which limits its practical value. The study by Campbell et al (1992) isolates the uniaxial strain by taking advantage of the low Possion’s ratio of the host structure material. Thus, it is not generally applicable to other materials.…”

Peak wavelength interrogation of fiber Bragg grating sensors during impact events

“…The sensor embedment permits the sensor to be located near the site of interior damage and shields the sensor from debonding during impact events [8]. Other sensors have been applied for similar applications including PVDF films [9,10] and Fabry-Perot etalons [8]. Fabry-Perot etalons can be embedded in the laminates, however their larger size, in comparison with FBG sensors, can be detrimental to the performance of the laminate itself.…”