Mechanical Model On Interaction Between Drill Bit And Lunar Soil And Finite Analysis

In order to gain and analysis lunar regolith in situ or back to earth, to design a high reliable, long life WC coring bit has become the main objectives and tasks.The mechanical model on the interaction between cutter and lunar soil is researched in this paper in the base of the mechanical and physical properties of lunar soil. The mathematical equations of torque and WOB on the structure parameters of drill bit and parameters of lunar soil are calculated and the influence of various parameters on the torque and WOB is analyzed. It is concluded that the rake angle and the distance between cutter and axis of drill bit are the important parameters for toque and WOB. The torque is positively correlated to the width of the cutter and the distance between the cutter and the axis of the drill bit. The WOB is negatively correlated to the rake angle. The influence of width of the cutter on the torque is weaker and the tip angle on the torque can be neglected.The transient dynamic contact analysis module of ANSYS is used to simulate the process of cutter cutting lunar soil and to analyze stress and strain effect surrounding soil with cutter size changes. The results indicate the maximum von mises stress and strain that the soil suffered decreased and the ability of cutters cutting lunar soil reduced when the distances between cutters and axis of the bit increases and the positive rake angle decreased. The impact of cutter width on cutting soil ability is weak. The simulation results are virtually in accordance with the theoretical ones, which can be used to guide the optimization design of sampling bits.The maximum von mises stress of cutters increase with the increase of the elasticity and Poisson ratio of lunar soil. So, it is more difficult for cutters to cutting into the lunar soil.When the WOB range from300N-420N, the maximum stress and strain of lunar soil increases as the rotational speed increases and gain the biggest value when the rotational speed is175rpm/min.That is to say the ability of cutters cutting lunar soil is strongest. The maximum von mises stress and strain of lunar soil is positively correlated to the axial displacement.