Bionic Research In Surface Of Traveling-Sand Wheel Based On The Adhesion Property Of Ostrich Planta

It is essential to have a good traveling ability on sand for a car when they are working for exploiting oil on desert or exploring on deep space.But cars always have an inferior traveling ability even land themselves in sand because the cohesive force of the sand is small and the sand can flow easily.As the only part of the wheel,the surface of the wheel play a key role in improving the traveling ability on sand.Ostrich can run fast on sand,the planta of ostrich have a good adhesion property on sand.A bionic surface of wheel was designed based on the planta of ostrich,which have a significance on improving traveling ability of car on sand environment.Stereomicroscope and Scanning Electron Microscope were used to observe the plantar papillae of ostrich.In macro level,a single papilla was composed by 3 to 5 circular layered structure.Newborn papillae were found among old papillae.Those newborn papillae and layered structure can prevent the plantar skin from abrasion.In micro level,the single papilla was hollow.We inferred that this structure can impede the conductor of heat from the sand on desert.From the vertical section,single papilla was composed by interlocking fibers.Those fibers can increase the strength of extension and wear-resistance property.From the root to the tip of a single papilla,the macro structure became rougher,but the micro structure became smoother.We also surmised that those structure can contribute a lot for wear-resistance.The planta of ostrich was divided to ten parts artificially.The size of papillae were collected which would be used on later bionic design.An equipment was designed and manufactured for measuring adhesion coefficient between the planta of animal and substrates on the land.The principle of this equipment was represented and some force of friction was calculated.Adhesion coefficient between wood and steel,rubber and steel were measured to compare with reference data to finish the calibration of the equipment.Nearby the zero degree position,adhesion coefficient between planta and single-layer sand was 0.64 to 0.9,which indicated that the plana of ostrich have a good adhesion property on single-layer sand.On circumferential angle position,adhesion coefficients between planta and 200 mm depth sand were measured every other ten degree.Nearby one hundred and eighty degree,the adhesion coefficient was the biggest which was corresponding to the braking of the ostrich.Nearby the zero degree,the adhesion coefficient was the smallest which was corresponding to the walking or running in a straight way of ostrich.On other parts of the circumferential,the adhesion coefficients were between the one hundred and eighty degree and zero degree,which corresponded to the veer of ostrich.One hundred and eight degree position would be a reference in later bionic design.We hypothesized that the papillae can increase the adhesion property on sand.Some tests showed that the papillae can increase the adhesion property notably.3D scanner was used to obtain the curved surface of the planta.Geomagic Studio and CATIA were used to deal with 3D data to gain a curve.Based on the curve and former test data,bionic surface of wheel on sand environment was designed with convex body.Simulations,which was done by EDEM,were used to find the best size of the convex body.At last,we gain the biggest adhesion force when the size of the convex body and the height of them were 2mm.Based on the best size of convex body,bionic surface and normal surface of wheel were manufactured.Those surfaces were used to do some tests which called forward direction pulling plate test and reverse direction pulling plate test.Test data showed that the adhesion property of bionic surface was better than normal surface.Test data also showed that only the bionic surface cooperated with convex body can achieve good effect.Arrayed the surface to be a whole wheel 3D model.Imported the 3D model to EDEM to do some simulation.The results showed that thrust force of bionic wheel was 113.4% larger than normal wheel.Bionic research in surface of wheel on sand environment can afford new thinkings and design references for improving traveling ability of wheel on sand enviroment.