Study On Anti-skid Tread Structure On Ice Surface Based On Reindeer Foot

Reindeer lives in frigid areas and possesses the superior walking ability on ice.Reindeer feet are the exclusive parts which contact with the ice directly.The sole characteristic morphology is the key factors to the excellent anti-skid performance.The research of the reindeer feet characteristics will help to apply the superior characteristics to snow tire tread and improve the trafficability property of tire on ice ground.The size of reindeer foot was determined and the ungula cusp,the ungula sole,the ungula edged,the ungula sphere were determined.We carried out the gross anatomy of the reindeer foot and found that organization structure is similar to other artiodactyl animals.Stereo microscope(SM)and a scanning electron microscope(SEM)were used to observe four key characteristics of reindeer foot.Element contents of the three characteristics of reindeer foot were checked using the SEM equipped with EDS(energy dispersive spectroscopy).The results show that surfaces of each characteristic site exhibited different morphology.In the microscopic analysis,the surfaces of ungula sphere and ungula sole had irregular laminated structure.We found that the surface ungula edge were smooth.The ungula cusp had unique features and was worn seriously.Reindeer foot included some elements,such as S,Si,Fe,Al and Ca,except C,O and N.The elements content of different parts was discrepant.Ti was the particular element on the ungula sole.Ungula edge lacks of Mg and S elements that other parts containThe geometric point clouds of the reindeer feet were obtained by using a 3D hand-held non-contact laser scanner.After that,the data were imported to Geomagic Studio software and we reconstructed the analytical model.The reconstructed model of reindeer foot was divided into four typical characteristic areas: the edge curves(inside edge and outside edge),the ridge groove surface and spherical cap surface with the cutting function of the software.In addition,these point clouds were imported CATIA to be filtered and transformed.Through the above processes,the 3D coordinate data points of these characteristic areas were exported.The edge curves were fitted using curve fitting software 1stOpt,and then,fitting equation and solution fitted parameters were acquired,respectively.We also used the Surface Fitting function of Matlab software to fit two surfaces: ridge groove surface and spherical cap surface.Finally,two surface fitting models were achieved.The fitting results revealed that the R2(coefficient of determination)of two curves and two surfaces were 0.994,0.992,0.96,0.98,which were all close to 1.It showed that the characteristic areas of reindeer feet were successfully transformed from the biological model to the mathematical model.In order to verify the model scientificity,we acquired the three-dimensional coordinate data of the same characteristic areas of other reindeer foot by adopting the same treatment.The mean relative errors of four models within 5%,which showed the mathematical models effectiveness in this paper.Combined with the established mathematical model of characteristic curve and surface and the actual structure of the tread pattern block,two bionic tread pattern blocks and contrasting herringbone block were designed in Solidworks software based on bionics principle.Using machining technology and 3D printing technology,the pattern blocks were processed out of the physical model.Tribological test of tread pattern block and ice surface on UTM friction tester.The experimental results show that under the same speed,temperature and pressure,the friction coefficient between the bionic and non striated tread pattern block and the ice surface is the highest,which is 1.13~1.47 times of the bionic striated tread pattern block,and is 1.04~1.26 times higher than that of the chevron tread block.Moreover,the temperature factors have the greatest influence on the friction coefficient between the three tread pattern blocks and the ice surface.Based on the ABAQUS thermo mechanical coupling analysis,we observed the temperature changes of the ice surface under the condition of the same environment,low pressure and high pressure,speed and time.The experimental results showed that the ice surface temperature under the bionic non striated tread pattern block increased by 0.66 degrees at the low pressure.The rising temperature is 3.1 times the ice surface temperature under the bionic striated tread pattern block,and 1.2 times the ice surface temperature under the herringbone pattern block.Under high pressure,the ice surface temperature under the bionic striated tread pattern block increased by 7.764 degree,which is 1.91 times the ice surface temperature under the bionic non striated tread pattern block,and is 2.29 times the ice surface temperature under herringbone pattern block.In the simulation of three kinds of tires and ice surfaces under high pressure,the ice surface temperature under bionic striated tread pattern tires increased by 11.5883 degree,which is 1.15 times of the ice surface temperature under bionic striated tread pattern tires,and is 4.55 times of the ice surface temperature under herringbone tread pattern tire.