Full Paper Development of poly(vinylidene fluoride-trifluoroethylene) films and its quasi-static and dynamic strain response (original) (raw)
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IJERT-Development of P(VDF-Trfe) Films and Its Quasi-Static and Dynamic Strain Response
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/development-of-pvdf-trfe-films-and-its-quasi-static-and-dynamic-strain-response https://www.ijert.org/research/development-of-pvdf-trfe-films-and-its-quasi-static-and-dynamic-strain-response-IJERTV2IS120955.pdf Thin films of poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) were prepared using solvent cast method and characterized for structural, mechanical and surface morphological properties to investigate the presence of β-phase through X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, Raman and Infrared spectra, and tensile testing. The conditions to achieve β-phase of P(VDF-TrFE) have been discussed in detail. Following the material characterization, the fabricated β-phase P(VDF-TrFE) sensors have been tested for dynamic strain sensing application. Time response from the β-phase P(VDF-TrFE) sensor due to the free vibration and impact on beam structure is obtained and is compared with β-phase PVDF sensor and conventional piezoelectric wafer type sensor. The variations in the frequency response spectra due to free vibration and impact loading conditions are also reported, which reveal the fact that the sensitivity of the β-phase P(VDF-TrFE) sensor to various modes of vibration is same as the β-phase PVDF sensor. The resonant and anti-resonant peaks in the frequency response of β-phase P(VDF-TrFE) films match well with that of β-phase PVDF sensor and Lead zirconate titanate (PZT) wafer sensors. Thus the fabricated β-phase P(VDF-TrFE) sensors can be effectively used as the dynamic strain sensor.
The beta-phase of polyvinylidene fluoride (PVDF) is well known for its piezoelectric properties. PVDF films have been developed using solvent cast method. The films thus produced are in alpha-phase. The alpha-phase is transformed to piezoelectric beta-phase when the film is hot stretched with various different stretching factors at various different temperatures. The films are then characterized in terms of their mechanical properties and surface morphological changes during the transformation from alpha- to beta-phases by using X-ray diffraction, differential, scanning calorimeter, Raman spectra, Infrared spectra, tensile testing, and scanning electron microscopy. The films showed increased crystallinity with stretching at temperature up to 80C. The optimum conditions to achieve beta-phase have been discussed in detail. The fabricated PVDF sensors have been tested for free vibration and impact on plate structure, and its response is compared with conventional piezoelectric wafer type sensor. The resonant and antiresonant peaks in the frequency response of PVDF sensor match well with that of lead zirconate titanate wafer sensors. Effective piezoelectric properties and the variations in the frequency response spectra due to free vibration and impact loading conditions are reported.
Thin Solid Films, 2010
The residual stress and its evolution with time in poly(vinylidene-fluoride-co-trifluoroethylene) (P(VDF-TrFE) (72/28)) piezoelectric polymer thin films deposited on silicon wafers were investigated using the wafer curvature method. Double-side polished silicon wafers with minimized initial wafer warpage were used to replace single-side polished silicon wafers to obtain significantly improved reliability for the measurement of the low residual stress in the P(VDF-TrFE) polymer thin films. Our measurement results showed that all the P(VDF-TrFE) films possessed a tensile residual stress, and the residual stress slowly decreased with time. Our analysis further indicates that the tensile stress could arise from the thermal mismatch between the P(VDF-TrFE) film and the silicon substrate. Besides possible viscoelastic creep mechanism in thermoplastic P(VDF-TrFE) films, microcracks with widths in the range of tens of nanometers appeared to release the tensile residual stress.
Characteristics of Piezoelectric Polymeric PVDF Sensor by Impact Testing
Polymer Korea, 2019
The 18 wt% poly(vinylidene fluoride) (PVDF) fibers were near-field electrospun at a flow rate of 139 nL/min, an electric field of 12 kV/cm, and a collector speed of 500 mm/s. A PVDF fiber array consisting of 20 fibers was adhered to the flexible PET film. A PVDF and a lead zirconate titanate (PZT) sensors were attached at a distance of 5 mm from the clamped end of the Al cantilever. The vibration sensing capabilities of sensors were examined by measuring the potential generated by the sensors during impact testing. Although the voltage of PVDF sensor was 200 times smaller than that of PZT sensor, the waveforms of the sensor output were similar. Both sensors were determined to be sensitive to variations in the level of dynamic strain due to the inherent piezoelectricity. The spectral results of both sensors exhibited the same signal generated by natural frequency of cantilever.
Piezoelectric PVDF sensor as a reliable device for strain/load monitoring of engineering structures
IOP Conference Series: Materials Science and Engineering
This study investigates the potential of PVDF (polyvinyldiene fluoride) piezoelectric polymer material as a strain/load sensor for engineering structures. The PVDF sensor can be made in any shape/size and are flexible. In addition, the PVDF sensor is passive and offers the advantage of requiring no power to function. PVDF sensors were bonded to an aluminum specimen representative of an engineering structure and the voltage output of the PVDF sensors was found to vary linearly with the applied tensile load. This paper evaluates the possibility to make develop cheap, reliable and efficient sensors for structural health monitoring of engineering structures.
Sensors and Actuators A: Physical, 2010
Large-area PVDF thin films have been prepared and characterized for quasi-static and high frequency dynamic strain sensing applications. These films are prepared using hot press method and the piezoelectric phase (-phase) has been achieved by thermo-mechanical treatment and poling under DC field. The fabricated films have been characterized for quasi-static strain sensing and the linear strain-voltage relationship obtained is promising. In order to evaluate the ultrasonic sensing properties, a PZT wafer has been used to launch Lamb waves in a metal beam on which the PVDF film sensor is bonded at a distance. The voltage signals obtained from the PVDF films have been compared with another PZT wafer sensor placed on the opposite surface of the beam as a reference signal. Due to higher stiffness and higher thickness of the PZT wafer sensors, certain resonance patterns significantly degrade the sensor sensitivity curves. Whereas, the present results show that the large-area PVDF sensors can be superior with the signal amplitude comparable to that of PZT sensors and with no resonance-induced effect, which is due to low mechanical impedance, smaller thickness and larger area of the PVDF film. Moreover, the developed PVDF sensors are able to capture both A 0 and S 0 modes of Lamb wave, whereas the PZT sensors captures only A 0 mode in the same scale of voltage output. This shows promises in using large-area PVDF films with various surface patterns on structures for distributed sensing and structural health monitoring under quasi-static, vibration and ultrasonic situations.
Sensors, 2012
Due to advantages such as light weight, flexibility, and low cost, polyvinylidene fluoride (PVDF) films have been widely used in engineering applications as sensors for detecting strain, pressure, or micro-force. However, it is known that PVDF strain sensors have strain cross-sensitivity in mutually orthogonal directions. Furthermore, the size of the PVDF film sensor would also affect the dynamic strain sensing performance. In this paper, to investigate the cross-sensitivity and size effects experimentally, we employ PVDF film sensors to perform dynamic measurements on a cantilever beam. Since the vibrations of the cantilever beam are excited by impacts of a steel ball, the induced highly repeatable transient responses contain a wide range of resonant frequencies and thus can be used to investigate both the size and cross-sensitivity effects of the PVDF film sensors in a dynamic sensing environment. Based on the experimental results of the identified resonant frequencies compared with results obtained from a strain gauge, finite element calculations, and theoretical predictions, suggestions for the use of the PVDF strain sensor in modal testing are given in this paper.
Verification and Analysis of Characteristics of Polyvinylidene Fluoride Material
2017
Piezoelectric materials possess a unique property of generation of electric charge when mechanical energy is applied to them. Piezoelectricity is a form of changing mechanical energy into electric energy. In other words they are transducers which are capable of converting mechanical energy into electrical energy. It is light weight and flexible. The proposed work discusses about the verification and analysis ofPolyvinylidene fluoride material (PVDF) film. A series of experiments have been performed by applying compressive force on the PVDF material at various frequencies. To record and analyze the output of the PVDF film, a Data Acquisition System (DAQ) running Labview software was used. The experiments were performed on single layer PVDF material. The observations of hysteresis loops in single layer PVDF film were successfully performed. The experiments were performed on 9 micron thickness of PVDF film and the changes in the output voltage generated were observed.