Research On Dynamic Analysis And Wireless Sensors Of PVDF For Structural Monitoring

Since J. Curie and P. Curie discovered the piezoelectric effect in 1880, the research on piezoelectric materials has been developed rapidly. Over the past few decades, piezoelectric materials have been widely used in some high-tech fields such as laser navigation, biological engineering, aerospace, etc…Due to PVDF's (polyvinylidene Fluoride) prominent qualities of high mechanical strength, high sensitivity, easy layout, corrosion resistance, wide frequency response and so on, it has aroused wide concern in fields of sensor applications, structural control and structural health monitoring.In this paper, based on PVDF piezoelectric film, the author has completed the sensing mechanism analysis of PVDF, strain sensing and bridge damage detection experiments. Much research work has been done systematically on Imote2 wireless sensor network nodes from Crossbow Technology, Inc. and to build the platform for wireless PVDF piezoelectric signal acquisition.Firstly, according to the present situation of structural health monitoring and wireless sensor network, this paper has presented an idea to combine high-performance smart sensors with wireless sensor network nodes. Based on the piezoelectric effect and piezoelectric equations, this paper has not only studied the sensing properties of PVDF and the mechanism of structural strain monitoring, but also analyzed its working principle and paste technology, the equivalent measurement circuit. Through strain sensing experiment, the paper systematically studied the sensitivity, frequency response properties of PVDF sensors. Then PVDF is used in the bridge model. Based on PVDF, natural vibration frequency and damage detection experiments have been completed.Secondly, the paper has studied smart wireless sensor node Imote2, introduced its hardware structure,processor board, sensor board, battery board, and completed Imote2's environment setting based on Microsoft.Net Framework, ADC signal acquisition program design based on C # language.Finally, according to high-frequency-sensitive properties of PVDF, compared with the acceleration sensor on the shock machine, the paper analyzed the high-frequency impact properties of PVDF and combined PVDF piezoelectric film with Imote2 to build a wireless impact signal acquisition platform. The experimental results have shown PVDF's impact resistance, quick response,high sensitivity, and proved the feasibility of the experimental platform, the experiment also reflects the wide application prospects pf PVDF piezoelectric films and Imote2 wireless sensor nodes for structural health monitoring.