Study On The Self-cleaning Mechanism Of Bionic Grousers Based On Adhesion Characteristics Of Deep-sea Sediment

The increasing shortage of the land mineral resources makes us turn to ocean with rich mineral resources,and currently focused on pipeline hydraulic transportation system to meet the future commercial exploitation.In pilot phase of the mining system,grouser of the mining machine has a serious sticky sediment problem,which leads to mining machine sliding and mining efficiency decreasing due to the decline in effective shear height of the grouser,even threatens the safe operation of the whole mining system.Therefore,it is of great engineering significance to study the adhesion properties between deep-sea sediment and grouser interface and the self-cleaning performance of bionic grouser to improve the mobility and mining efficiency of deep-sea mining machine.Aiming at adhesion characteristics of deep-sea sediment,the discrete element theory and the soil adhesion theory are used to establish the mesoscopic-adhesion mechanics model for the deep-sea sediment collected from the Pacific C-C mining area.Using the discrete element platform,grain contact program with adhesion characteristics is developed to investigate self-cleaning mechanism of the bionic grouser for obtaining the mathematical description and control parameters of the self-cleaning bionic grouser.Finally,based on the dynamic test platform of adhesion characteristics,the walking characteristics of the bionic grouser are studied to verify its self-cleaning effect,which provides an important basis for its application in deep-sea mining technology in China.The main research results of this paper are as follows:1.Based on the deep-sea sediment collected from C-C mining area in the Pacific Ocean,the adhesion characteristics between deep-sea soil particles and five corrosion-resistant metals(aluminum alloy 5052,stainless steel 316 L,titanium alloy STi80,titanium TA2,titanium alloy TC4)were studied.The macroscopic mechanical properties and adhesion properties of deep-sea sediment were obtained by uniaxial compression and macroscopic adhesion tests.The results of uniaxial compression test show that the shear failure occurs in the direction of about 45 °along the axial direction,which is caused by the maximum principal stress,and the stress of deep-sea sediment increases linearly with the increase of strain in the range of stress.Therefore,it can be considered that the failure form of deep-sea sediment is brittle failure in the range of small deformation.The macroscopic adhesion test shows that the order of surface adhesion force between different metals and deep-sea sediment is 5052 <316L <STi80 <TA2 <TC4 under the same surface roughness,which indicates the self-cleaning effect of aluminum alloy 5052 metal interface is the best.2.Based on the JKR adhesion constitutive model,the adhesion characteristics of deep sea sediment-metal interface are described quantitatively,and the calibration of conventional meso-mechanical parameters and meso-adhesion parameters of deep-sea soil particles were carried out combined with the macroscopic adhesion test of deep sea sediment-metal interface.The DEM simulations were conducted for the parameter sensitivity analysis.The DEM simulation results are in good agreement with the laboratory experimental results in stress-strain response and surface adhesion force,thus realizing the calibration of conventional meso-mechanical parameters and meso-adhesion parameters of deep-sea soil particles.The sensitivity analysis of the parameters shows that the macroscopic parameters such as material density,Poisson’s ratio and shear modulus have little effect on the surface adhesion force,and the mesoscopic parameters,including static friction coefficient and rolling friction coefficient,also have little effect on the surface adhesion force.While the restitution coefficient and surface energy have great influence on the surface adhesion force.The surface adhesion force decreases with the increase of restitution coefficient,while the surface adhesion force increases linearly with the increase of surface energy.3.Based on the walking characteristics and calibrated mesoscopic adhesion mechanical parameters of deep-sea sediments,the effects of different waveform parameters and walking conditions on the surface adhesion force of bionic grouser of deep-sea mining machine are calculated and analyzed by discrete element method.The bionic self-cleaning mechanism of the bionic grouser is revealed,and the bionic crawler teeth with the best self-cleaning effect are obtained,that is,the self-cleaning effect of bionic grouser with waveform function Y=2sin(X/10)is the best.The results show that the self-cleaning performance of bionic waveform grouser is better than that of the smooth one.With the increase of cutting depth,the surface adhesion force of bionic grouser increases at first and then decreases.This is because: the increase of cutting depth will increase the effective contact area between bionic grouser interface and deep-sea soil particles initially,but as the cutting depth exceeds a certain depth,the surface configuration of bionic waveform reduces the effective contact radius between soil particles and interface,so the effective contact area is reduced.All the results provide basis for the study of the walking properties of deep-sea mining machine under complex working conditions.4.Based on Newton’s law of motion,the motion state of deep-sea soil on the surface of bulldozer is studied,and the self-cleaning mechanism of bionic bulldozer plate is revealed.It is found that the surface adhesion force between the bulldozer interface and soil reaches the minimum as θ = 45 °.At the same time,based on the best tooth profile bionic bulldozer obtained by discrete element simulation,the soil groove cutting experiments of the bionic plate and the smooth plate are carried out.And the self-cleaning mechanism and influencing factors of the bionic bulldozer are revealed,which provides a theoretical basis for the study of the bionic grouser shear deep-sea sediment.Based on self-cleaning mechanism and the influencing factors of bionic grouser,the physical measures are taken to reduce the surface adhesion force and improve the mobility and mining efficiency of the mining machine.