Study On Viscosity Sensor Based On Composite Piezoelectric Torsional Fiber Structure

Viscosity is an important physical parameter that reflects the kinematic characteristics of fluid.Viscosity measurement has a wide range of applications in industrial production and scientific research such as energy and chemical industry,biomedicine,food,environmental protection,and so on.Although the existing viscosity measurement methods can achieve high measurement accuracy,most of them are still bulky,complex,expensive,and difficult to real-time online measurement.Therefore,the development of miniaturization,high precision,low cost,fast on-line measurement of viscosity measurement technologies have urgent application needs and important research values.Regarding the above issues,a new kind of viscosity sensor based on composite piezoelectric torsional fiber structure is proposed in this dissertation,and the viscosity measurement method is optimized to obtain high measurement accuracy.Firstly,the vibration principle of composite piezoelectric torsional fiber resonator is analyzed,and the structural design of the composite resonator is optimized by finite element simulation.The composite resonator prototypes of three different materials of probes are fabricated and tested.Secondly,the vibration coupling characteristics between composite piezoelectric torsional fiber resonator and liquid are analyzed,the electromechanical equivalent circuit of vibration coupling is improved,and the viscosity measurement method based on admittance circle fitting is optimized.Finally,experimental test platform was constructed and viscosity measurement performances of the composite resonator prototypes of three different materials of probes were tested with glycerol aqueous solutions as the standard viscosity liquids.The experimental results show that the composite resonator with quartz probe has a high mechanical quality factor of up to 220 in air and a high viscosity measurement resolution;the composite resonators with stainless steel and beryllium bronze probes have good mechanical quality factors of up to 150 in air and a wide range of viscosity measurement.In general,the composite viscometers designed in this dissertation have good viscosity measurement performances,for which Rf has a good linear relationship with (?) in the range of 100 to 3500 mPa·s and the correlation coefficient R-square of up to 0.99953.The proposed new viscosity sensor,with the advantages of miniaturization,simple structure,wide range of measurement,and low cost,can be used for on-line liquid viscosity measurement,especially viscosity measurement of small space liquid and trace liquid in industrial production and scientific research processes,with a good application prospect in miniaturized high precision viscosity measurement.