Study On Bender Elements Method Of Real-Time Monitoring Lunar Soil Simulant Filling Density

Lunar exploration project has extraordinary significance for humans.It satisfies our curiosity,provides rich resources for the planet,reflects each country's comprehensive national strength and technological progress,so that many countries spare no effort in lunar exploration.Lunar exploration involves drilling,which should be tested on simulated lunar soil first in order to realize it on the moon.When filling in the test,in order to reliably simulate the lunar soil trends,real-time monitoring is required to monitor filling density of lunar soil simulant.In order to implement the lunar soil simulant filling density real-time monitoring,bender elements real-time monitoring systems is researched in all aspects in this paper.Studies have shown that increasing the distance between the bender elements,using insulated bender elements,keeping the wires from experiment device and shorting the wire length can reduce interference.With the amplifier input resistance increase,the shear waves propagating time decrease but increase as the feedback capacitance increase and time changes with the feedback capacitor larger and more obvious.The effect of frequency on the signal was studied,which shows that under the same length of the cantilever of bending element at a lower simulated lunar soil density,as the density increases,the signal becomes strong;but at higher simulated lunar soil density,signal strength decreases with the increase of density.The bender elements with different cantilever lengths were tudied,which shows that at low density different boom lengthes have no influence on the period ratio,integrity and readability,and these three values are maximum at around 1000 Hz.But the signal strength increase with the increase of the length of bending element cantilever.At high density shear wave signal can not be clearly measured when bending element with the cantileVer lengthes of 1.5cm,2cm and 3cm were used,but clear signal can be measured at all density with 1cm long cantilever bending element.This study showes that shear wave velocity in simulated lunar soil is dispersive,which means shear wave velocity increase with the excitation frequency increase.To solve this problem,readability weighted linear regression was used to analyze the relationship between frequency and density,which is represented in formula.basing on the formula,calibration curve can be obtained at any frequency and experiments show thus obtained calibration curve is reliable.This study provides detailed information on the testing process,studied the existing test problem and laid the foundation for further study of the system.This paper also made a simulated lunar soil density ~ shear wave velocity calibration curve at different frequencies and provides the basis for the monitoring of lunar soil simulant filling density.