Research On The Surface Feautre Of Earthworm And Its Adhesion Characteristic

Soil adhesion has been always affecting the work efficiency ofterrain machine also it is the primary problem of cultivation efficiency ofthe agricultural machinery. Reducing soil adhesion is a fundamental wayof increasing the work efficiency of agricultural machinery.The researchers all around the world are contributed themselves towork out a preferable way of solving the adhesion problem. However, soilis a complicated multiphase system, the reasons of soil adhesion arenumerous, thus it just could reduce the soil adhesion to a certain extentinstead of a thorough solution. Therefore, no other than consideringvarious factors such as machining, usage, economy and environment thatcould a method be regarded as an excellent one. Looking for a solutionfrom the natural might be a feasible way of reducing soil adhesion. As aresult, nowadays it has been a main research direction of the fundamentaltheoretical research in agricultural machinery to investigate the soilanimals for reducing soil adhesion.Soil animal had an outstanding ability to reducing soil adhesion afterhundreds and millions years of evolution. It was discovered that thenon-smooth surface of soil animals was one of the main reasons for itsreducing soil adhesion;whereas, a great many had not been researchedbecause of the large quantity of the species. Earthworm is a typical soilanimal that has a fine ability of reducing soil adhesion, theelectrophysiology and body surface liquid may be the primary reasons.The body surface feature might be another cause of reducing soiladhesion. However, this has not ever been studied due to the limitation oftesting condition, so it was the chief research of this dissertation toinvestigate the relationship of the surfacer feature on earworm and itsability of reducing soil adhesion.The Pheretima Praepinguis was used as research object. The planepictures of the live earthworms and the body surface specimens weretaken by digital camera and stereoscopic microscope (XTJ30). It wasdiscovered that there were differences between the head feature and thebody's. The differeces might be explained as the head was the leadingpart of reducing soil adhesion. The 3D images of the live earthworms andthe body surface specimens were taken by the 3D Laser Scanner ControlSystem. The curvature of the head segment was analyzed by Imageware.It was detected that the curvature was various more steadily in parallelthe moving direction than that in the vertical direction. The minimumcurvature is on the connecting part of segments in parallel the movingdirection. This appearance might because the earthworm need a biggersoil cutting angle when it digging into the soil. In vertical the movingdirection, the minimum curvature is existed on the two sides of thesurface, the configuration let the soil easier to slide form the earthworm.At the same time, the apparent roughness (AR) of the body surfacespecimen was calculated based on the scanned 3D data, the head AR wasgreater than the body's.The result also showed the head's importance inreducing soil adhesion.The relationship between the surface feature and wettability was alsoresearched. The apparent contact angle (ACA) of the body surfacespecimen was tested by the OCA20. It is displayed that the greater ARwas the higher ACA was. This result proved the rippled non-smoothsurface enhanced the wettability of the body surface specimen.A tiny adhesion testing system was developed and the adhesionexperiment of earthworm's surface specimen was designed. The resultshowed that, the adhesion of the surface specimen was much steadycompared to the steel specimen and the head showed better reducing soiladhesion ability. The adhesion of body surface increased with AR'sincrease, which might be caused by different body feature. It is analyzethat the earthworm's body maybe supply the friction when it moves.The result of orthogonal experiment indicated that pressure and theunload velocity were two primary factors of adhesion. Several equationswere obtained based on the one factor regression experiment. The surfacespecimen and steel specimen equations between adhesion and pressurewere: y=-493.57+5.55x and y=192.176+5.542x, the adhesioncharacteristic between surface specimen and steel specimen are similar,the maximal reducing soil adhesion ratio of surface specimen was 23%under the experiment condition. The surface specimen had thecharacteristic of reducing soil adhesion. The surface specimen and steelspecimen equations between adhesion and unload velocity were:y=327.607+204.293x,y=1276.718+509.042x.The result showed that themaximal reducing soil adhesion ratio of surface specimen was 64.7%. Thesurface specimen not only had the reducing soil adhesion characteristic,but also had a steady ability of reducing soil adhesion. Concluded by theorthogonal regression experiment, the quadratic equation betweenadhesion and these two factors was:216124y = ?0. 017+0.0027Z1 ?0.008Z2+1.91×10? ZZ+2.34×10?ZThe regulation of adhesion and soil containing moisture was alsodiscussed in the dissertation, the surface specimen equation was:y=-495.4+49.09x,the steel specimen equation was:y=12696.7-1095.6x+25.322x2, the result showed that the maximalreducing soil adhesion ratio of surface specimen was 77.23%, the surfacerepresent an obvious abilty of reducing soil adhesion.Besides, the influence of the earthworm's body surface liquid to theadhesion was studied. The result of the with-liquid experiment manifestedthat the body surface liquid increased the adhesion of both surfacespecimen and steel specimen. The adhesion increased because the bodysurface liquid made interface joint tightly resulted in the vacuum negativeair pressure of the interface, and the vacuum negative air pressure finallyincreased the adhesion.