Soil Adhesion Preventing Mechanism of Bionic Bulldozing Plates and Mouldboard Ploughs

Abstract

Soil adheres to the surfaces of soil engaging components of various tools. The adhesion of soil increases the draft and adversely affects the quality of work. For example, up to 50% of the gross energy required for tillage operations may be consumed by adhesion and friction between soil and tillage tools. Therefore, it is important to find out the ways to reduce adhesion of soil to the surfaces of various tools. Soil animals such as ground beetles stay in moist sticky soils for extended periods without soil sticking to their bodies. The soil adhesion preventing mechanisms of such animals can be used as guide for improving the scouring properties of various tools. Both the surface morphology and chemical composition of soil animal’s cuticle play important role in preventing adhesion of soil to their bodies. The surfaces of mouldboard ploughs and bulldozing plates were modified based on the surface morphology of ground beetle and tested in the laboratory. Two materials such as Steel-45 and Ultra High Molecular Weight – Polyethylene (UHMW-PE) were used for convexes. The modified ploughs and plates have better scouring properties and required less draft than conventional tools. The size of convexes, their arrangement and the material of these convexes played important role in reducing adhesion and scouring soil. UHMW-PE had better scouring properties and improved wear resistances than steel-45. This paper covers the modified ploughs and bulldozing plates where UHMW-PE convexes were used for modification. The distribution of these convexes on the surfaces of bulldozing plates and mouldboard ploughs resulted in changes in mechanical characteristics and the state of water film at soil-tool interface. The unsmoothed surface morphology broke down the continuity of water film, reduced the area of contact and increased pressure at soil tool interface. The higher pressure squeezed out more water and reduced the water tension. This process was helpful in reducing friction and adhesion of soil to the surfaces of modified tools. The drafts of modified plough by bionic using UHMW-PE convexes were reduced by 25% and 30% at 3.6 km/h and 4 km/h working speeds respectively. The draft reductions in bionically modified bulldozing plates were 27%, 27% and 29% less than the conventional plates operating at 0.01, 0.02 and 0.06 m/s speeds. Key words: adhesion; bionic; unsmoothed; mouldboard ploughs; bulldozing plates; draft