Studies On Cable Force Sensor Based On Magneto-electric Composite Materials

With the increasing popularity of bay bridge steel cable force testing as an important means of bridge health monitoring, widely applied in engineering. The cable force test accurate or not directly related to the bridge construction quality control and safe operation of the bridge has become a major topic in the field of public safety. The principle of cable tension sensor based on magneto-electric composite material is the principle of magneto elastic effect method and the steel cable body is the sensor core. The sensor uses the magnetic properties of steel cable with cable force, by testing the induced voltage magneto-electric composite outputs, to achieve accurate measurement of cable force. In order to achieve the engineering application, this paper carried out the following theoretical and experimental research work: sensor system structure, preparation process, equivalent magnetic circuit method, temperature compensation technology:1. In view of the requirement of cable force testing of high precision, high sensitivity, high stability in engineering, designed and prepared magnetic elastic multilayer magnetoelectric composite cable force sensor. Under the condition of the optimal structural parameters, using the epoxy resin, silver conductive adhesive and coating thickness control technology, making the layered magneto-electric composites. Using small leakage magnetic field and good anti-interference magnetic circuit structure design, composite driving magnetic field and the work scope of bias magnetic field were obtained through the finite element method. The precision of test and response time tests were conducted in the tensile testing machine. Research shows that: magneto-elastic cable force sensor measurement precision is high and has fast response.It fully meets the requirements of cable force test.2. In view of the magneto-elastic sensor installation and maintenance of the engineering application problem,proposed a bypass structure of magneto-elastic stress sensor, the overall structure of the device is proposed. Applying the law of magnetic circuit and the equivalent magnetic circuit method, the magnetic circuit structure of the cable force sensor of sleeve structure is analyzed systematically. Based on the principle of equivalent magnetic circuit, the bypass type structure of cable tension sensor is designed. The experiments between induced voltage and tensile experiments of two sensors were made. The results show that: the bypass type sensor precision can satisfy the detection requirements; under the condition of long-term work, the measuring accuracy is higher than the sleeve type sensor.3. In view of the characteristic of the sensor performance affected by the internal and external temperature, based on the analysis of the temperature influence factors, differential temperature compensation structure is proposed; the corresponding temperature compensation circuit is designed; the experimental of temperature compensation is studied systematically. Research shows that: the precision of the differential cable force sensor meets the requirements of the cable force measurement; realizes temperature compensation of the whole temperature range; solved two major problems: the engineering application and the temperature compensation.Theoretical and experimental studies show that the steel cable force detection technology based on the magneto-electric composite materials suitable for the complex environment of steel cable force of high precision, high reliability testing and engineering application.