| As the key supporting equipment,bolt is famous for ensuring the safety of roadway and roof.Considering the complexity of the underground environment,in order to provide a safe working space for the promotion of coal mining and comprehensive mining equipment,the staff need to know the roof pressure and bolt support status in time,so as to ensure the safety of the roadway.Therefore,in view of the shortcomings of low accuracy and easy to be affected by the environment,a new type of bolt axial force monitoring device is designed,which is low-cost,no power supply,360° remote observation and suitable for large-scale installation.The design and analysis methods are as follows:(1)Through the combination of light and mechanics,the pressure color relationship of the sensor is determined.The sensor can display different colors under different axial forces on the basis of light,so as to achieve the purpose of monitoring the axial force of the anchor rod.Then,according to the initial anchor,working and breaking state of the anchor,the corresponding color is determined.The color corresponding to 80% of the breaking force is selected as the final color.Then,the structure size design,material selection and optical path analysis of the color sensor are carried out with the axial force corresponding to the final color.Thus,the stress color calibration and optical path construction of the sensor monitoring system are completed so that the sensor can display the specified color under the calibration pressure.Finally,the sensitivity and uniformity of the sensor are determined according to the color sensitivity and uniformity index.(2)Based on hydrostatics,the static simulation based on fluid structure coupling is carried out according to the structure and material properties of the color sensor.Then,the corresponding fluid element and shell element are coupled one by one.According to the incompressibility of liquid under medium and high pressure,the strength of the whole sensor is checked and the stress distribution of some modules is determined.Taking 160 k N as an example,the stress and displacement changes of the three-dimensional nodes of the color ring section under the calibration pressure are analyzed.And further determine the stress change under the additional calibration pressure such as 60 KN,80KN,110 k N and130 k N.Through statistical analysis,the corresponding relationship between pressure and color is defined,so as to determine the sensitivity of the sensor.Correspondingly,the node stress in the color ring within this pressure range is also statistically analyzed.The color uniformity of the sensor in axial and circumferential direction is determined in the range of 0 ～ 160 k N,so as to ensure the color uniformity of the sensor in the whole process of stress and easy to observe.(3)According to the thermodynamics and the actual temperature change,the thermal structure coupling simulation of the sensor is carried out by using ANSYS software.Based on the data statistics of the stress changes of the crosssection nodes of the color ring,the influence of the same pressure and different temperature on the sensitivity of the sensor is analyzed.Then,the influence of liquid thickness and elastic pad thickness on sensitivity and uniformity is analyzed,so as to optimize the parameter size of the sensor and determine the optimal solution.So that the sensor is safe and reliable in the whole working process.(4)The working state of the sensor is verified by the sample processing,and it is found that the test results are consistent with the ANSYS calculation results.It meets the design requirements and the color is pure.Then,the applicability and feasibility of the sensor in engineering application are determined by analyzing the influence on the color uniformity and sensitivity when the sensor is under bias load and different temperature. |
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