Wireless Passive Flexible Strain Sensor For High Speed Bearing

In recent years,strain sensors have developed rapidly,and strain monitoring is widely needed in aerospace,power industry,machinery manufacturing,energy exploitation and other fields.To meet the demand of strain testing on high-speed bearing,a wireless passive flexible strain sensor is designed.The sensor realizes wireless signal monitoring through electromagnetic coupling,and has the characteristics of no power supply,and can monitor equipment strain through the change of resonant frequency.Using flexible material as the substrate can better produce cooperative strain with bearing fitting.In this paper,a wireless passive strain sensor is developed to detect the tiny strain produced during the operation of bearings,so as to find faults in time and reduce losses.The main research contents are as follows:1.The strain sensors at home and abroad are studied,and the working principles and testing methods of various strain sensors are analyzed.The forked finger capacitive strain sensor is selected,its sensitive mechanism is analyzed,the corresponding equivalent circuit model is established,and the principle of electromagnetic coupling is analyzed.2.Finally,Polyimide(PI)thin film is selected as the sensor base,and copper is used as the capacitance and inductance material.The structure of the strain sensor is preliminarily designed and simulated.The size of the sensor is adjusted according to the simulation results and the structure is optimized.The optimal coupling distance between sensor and antenna is obtained by simulation,which lays a foundation for the follow-up work.In addition,the electric field distribution of strain sensor is analyzed,which provides theoretical verification for the feasibility of strain sensor preparation.3.The preparation method of capacitance and inductance and the deposition method of thin film of wireless passive strain sensor were studied.The interfinger-electrode was prepared by electroplating technology and Al N thin film was deposited by pulse laser deposition technology.The sensor was effectively prepared according to the structure optimized by simulation..4.A strain testing platform was built.First,the cross capacitance of wireless passive strain sensor is preliminarily tested.The test results show that the capacitance decreases with the increase of strain,which is in line with the expected result.The measurement range and resolution of the sensor are tested.The test results show that the wireless passive strain sensor can work stably in the range of 0～3000 με,and the strain resolution is up to 20 με.In this paper,the coupling mechanism,design,manufacture and testing method of wireless passive strain sensor are studied.The sensor finally produced has the advantages of small volume,large range,high resolution and wireless monitoring,and has broad application prospect in engineering.