Development And Research Of Multi-Channel Tire-Road Three-Way Contact Stress Test System

When analyzing the dynamic response of asphalt pavement during vehicle driving in China,it is assumed that the pavement is a multi-layer elastic layered system,and the load on the pavement is a double-circle uniform vertical load,and the dynamic effect and non-uniform distribution of the load are not considered.state,which is quite different from the actual pavement stress distribution.In this paper,considering the influence of dynamic load and field test,a test system for real-time measurement of tire-road three-dimensional contact stress is developed.The system is mainly composed of three-dimensional force sensor,bottom plate,acquisition system and display.(1)In order to better reflect the stress distribution of the contact surface,a strain type threedimensional force sensor is designed based on the resistance strain effect.The sensor has the characteristics of small size,high precision and large range.The sensor is simulated and analyzed by AB AQUS software.In the range of the sensor,different gradient loads are applied to the X,Y and Z directions of the sensor,and the Mises stress and the maximum main strain of the strain gauge position of the sensor are analyzed.The results show that within the range,the strain is linearly positively correlated with the applied load,and when the load is applied to one direction of the sensor,the other two directions will also produce strain.The sensor has the influence of dimensional coupling.(2)Verify the structural safety of the bottom plate.Firstly,the finite element model of the bottom plate is established,and then 19.2 t,9.6 t and 9.6 t loads are applied to the vertical and horizontal directions of the bottom plate,respectively,analyzing the maximum principal stress of the sensor area.The results show that the maximum stress of the bottom plate is far less than its allowable stress,and the structure design of the bottom plate is reasonable.(3)Based on virtual instrumentation and FPGA technology to architect a multi-channel synchronous pressure acquisition system.Firstly,the core modules of the acquisition system such as the embedded system controller,FPGA backplane,synchronous acquisition module,strain signal conditioning module and software are introduced,then the working principle of the acquisition system is explained,and finally the operation of the acquisition system is explained.(4)The signal conditioning circuit of the acquisition system is described.Firstly,the signal amplification circuit is described,and the three operational amplifier instrument amplifier is used to amplify the signal.Then the filter circuit is explained,using a Butterworth digital filter circuit technology.Finally,the temperature compensation circuit is illustrated,and the bridge compensation method is used to compensate the temperature.(5)The sensors are calibrated to obtain the voltage sensitivities of the installed 32 sensors,and the calibration data is fitted into a curve by the least squares method to obtain the calibration matrix,and then the decoupling matrix of the sensor is obtained by inverting the calibration matrix.Finally,the static coupling rate is used to evaluate the coupling of the three-dimensional force sensor.The static coupling rate of the sensor Z and X and Y directions are 1.86%and 1.58%,respectively,and the coupling rate of the X and Y directions is 0.46%.Interdimensional coupling has little effect.