| In view of the characteristics of high stress and rapidity when rock burst occurs,a 6.5 MN hydraulic impact testing machine with large load,high speed,static and dynamic composite loading is developed to meet the test and research conditions of anti impact support equipment;The wheel spoke force sensor is used to measure the load of the testing machine,but the current technology can not calibrate the force sensor of 6.5 MN range level dynamically.In order to ensure the reliability of the measurement,the dynamic analysis of the sensor is carried out.The overall design of the spoke pressure sensor is carried out.The static and dynamic characteristics of the sensor sensitive elements are analyzed.The measuring circuit of the 6.5MN sensor and the basic structure of the sensor elastomer are designed.The static analysis of the stressed spoke in the sensor elastomer shows that the deformation of the spoke is a combination of bending and torsion.The strength of the spoke is checked,and the expression of measurement sensitivity is derived.The results show that the spoke section size of the large range sensor is large,and the shear stress is the main one in the spoke,and the maximum shear stress is between the bending maximum shear stress and the dislocation phase shear stress.The maximum shear stress is different with different section size.ANSYS Workbench is used to study the influence of the spoke geometry of 6.5 MN sensor elastomer on the stress distribution.It is concluded that the main influencing dimensions are the aspect ratio,the length and the number of spokes.Under the same cross-sectional area,the safety factor is positively correlated with the aspect ratio,and the difference and average value of the stress along the edge of the area where the strain gauge is pasted are negatively correlated with the aspect ratio;Under the same aspect ratio,the more the number of spokes,the greater the safety factor and the smaller the stress difference;Under the same section size,the spoke length is inversely proportional to the safety factor,the stress difference,the change rate of the stress difference,and the stable section of the first principal stress in the height direction of the center line,and is directly proportional to the average value.The constrained mode of 6.5 MN sensor elastomer is analyzed,and the minimum modal frequency is 5379.5 Hz.The dynamic characteristics of the sensor are analyzed,the mathematical model of the sensor elastomer is established,and the forced vibration is analyzed from time domain and frequency domain.The results show that the transient response time of the system is less than0.15 ms under linear excitation,sinusoidal excitation and step excitation,the response linearity is good,and the elastomer can respond to the excitation signal immediately.The transfer function of the whole system is deduced,and the frequency response function is analyzed.The cut-off frequency of the sensor is 14.6 k Hz,and the frequency bandwidth of undistorted measurement is0 ～ 14.6 k Hz.The variation amplitude and phase lag are positively related to the signal frequency.At 1000 Hz,the variation is less than 0.5%,and the phase lag is less than 0.0487°。The calibrated sensor is used to measure the impact force of the testing machine under two different impact loads.The spectrum of the two groups of impact force is obtained by fast Fourier transform.The main frequency of the impact signal is less than 50 Hz,which is far less than the undistorted measurement bandwidth.At this time,there is no amplitude error in the system,and the phase lag is less than 0.00223°,It is concluded that the sensor is reliable under the impact load. |
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