Study On Optimization Of Bionic Furrow Opener Based On Earthworm Corrugated Lubricated Surface

The phenomenon of soil adhesion occurs often when terrain machine interact with soil.Adhesion has an important influence on the working efficiency,service life,passing performance and working quality of terrain machine.Soil animals such as earthworms can move freely in different soil environments without soil adhesion,which is the result of coupling effects of earthworms such as non-smooth body surface,dynamic peristalsis,surface lubrication and electroosmosis.This provides a bionic idea for solving the adhesion of the soil contact parts.In order to improve the desorption and drag reduction performance of the soil contact parts,the bionic optimization of the core furrow Opener was studied by using the bionics principle and taking earthworms as the bionic prototype,so as to provide reference and basis for the viscosity and drag reduction of the soil contact parts.Using the Pheretima aspergillum as the biological prototype,Based on the nonsmooth corrugated surface and the function of biological lubrication of earthworms,four bionic furrow openers were designed.Firstly,the contraction curve of earthworm head was extracted,and the soil-entering part at the front of the curve was applied to the ridge line of the core to design the bionic ridgeline opener.Secondly,the corrugated structure in the middle and rear part of the curve is applied to the side line of the core to design the bionic corrugated opener.Finally,combining the characteristics of the two kinds of furrow opener to design the bionic composite opener.In order to realize the self-lubricating function,the bionic composite opener is lubricated and named as the self-lubricating bionic opener.The discrete element method was used to simulate the drag reduction performance and the soil contact interface of the opener.The results showed that the order of ditching resistance from large to small is traditional opener,bionic corrugated opener,bionic ridgeline opener,bionic composite opener.The drag reduction effect of the three bionic openers increases with the increase of the ditching depth.The bionic composite opener reached the highest drag reduction rate of all bionic openers when the depth is 60 mm,the speed is 100 mm/s,and the value is 9.08%.Three bionic openers have smaller ditch width and soil disturbance than the traditional opener,and have better soil backing effect.The bionic ridgeline opener has a better penetration performance because the rake angle increases gradually and smoothly along the core ridgeline.The corrugated structure can guide the particles to run in the vertical direction,increase the ditch height and reduce the ditch width,and relieve the force applied by the particles to the surface of the core from the tip of the core to the entire core surface.The corrugated structure creates a gap between the surface of the core and the particles,reducing the number of contact and contact area of the particles.The force field of the bionic composite opener is the smallest,and the soil disturbance of the core surface is small and evenly distributed along the core surface.Single factor experiment on ditching resistance: The ditching resistance increases with the increase of soil moisture content,soil hardness,ditching depth and ditching speed.Multivariate orthogonal polynomial regression experiments were carried out to investigate the drag reduction rate of the bionic composite opener,and the optimal level of primary and secondary factors is as follows: When the soil hardness is 3,the ditching depth is 60 mm,the ditching speed is 500 cm/min,the soil moisture content is 20%,reached the maximum drag reduction rate is 20.5%.The regression equation of factors and drag reduction rate is established.The drag reduction rate increases with the increase of soil hardness and ditching depth,and increases first and then decreases with the increase of ditching speed.The surface mucus secreted by earthworm during the process of progression forms a weak shear layer between the soil and the surface of earthworms.This weak shear layer has good fluidity and plays a role of fluid lubrication,which reduces the soil adhesion and resistance.The soil moisture content conditions of the lubrication test were explored.When the soil moisture content is small,the opener lubrication will promote the adsorption of soil particles and water molecules,and increase the soil adhesion.When the soil moisture content is large,the soil particles are in an overall plastic state.Lubrication releases water molecules and reduces the soil adhesion and resistance.According to the soil moisture content test,when the soil moisture content is 30%,the lubrication drag reduction effect is the best,and the average drag reduction rate is 21.15%.The optimal hole arrangement of the lubrication holes was tested,and it was found that the lower holes and the outer holes had the minimum ditching resistance.Lubrication test was carried out by multiple orthogonal polynomial regression experiments,and the optimal level of primary and secondary factors affecting the drag reduction rate of bionic opener is as follows: lubricant flow rate was 0.1,soil moisture content was 30%.The regression equation of factors and drag reduction rate of bionic opener is established.The relationship between each single factor and the drag reduction rate was obtained.The drag reduction rate increases with the increase of lubricant flow rate,and increases first and then decreases with the increase of soil moisture content.