Biomimetic Study Of Anti-skid Tire Tread For Icy And Snow-covered Road Environment

China’s vast territory,meteorological conditions are very complex,frozen areas occupy up to 75%of China’s land area,early spring and winter season road snow and ice will seriously affect traffic safety.And unlike other media,snow and ice in the occurrence of friction,due to the heat generated,the surface will appear liquid film,play a lubricating effect,making it has a smaller coefficient of friction.The tires,as the only part of the wheeled vehicle in direct contact with the ground,transmit all the ground forces on the vehicle,and their surface structure can directly affect the handling stability,driving comfort and passability of the vehicle.Compared with the conventional winter road environment,icy and snow-covered roads have more complex mechanical characteristics,which makes tires more likely to produce huge amounts of slip and sink when driving on icy and snow-covered roads.Therefore,this paper takes reindeer,which has excellent athletic ability on snow and ice,and seahorse,which can climb steadily on solid-liquid surfaces,as bionic prototypes,combines their biological characteristics with wheel tread patterns,and processes,tests and simulates the designed tires in order to seek to overcome the problem of vehicle passability on snow and ice,and to provide a basis for the bionic design of tire surface patterns.The morphological and structural measurements of reindeer hooves were conducted and the functions of each part of the hooves during their movement were analyzed.Both the hoof shell and the fleshy hoof play a supporting role,while the harder hoof shell also has the function of cutting into the ice and snow layer to increase friction,and the less hard fleshy hoof has a better function of snow fixation.Combining the type of tire tread pattern and the previous research of the group,the bionic tread pattern is optimized and processed.The physical properties of snow and ice,mechanical properties and friction theory of rubber were investigated,and the snow for the test was divided into loose snow and dense snow according to the density.The mechanical tests on the friction properties of rubber blocks with different arrangements were conducted by UTM friction testing machine under separate loose snow and dense snow,considering three test factors of snow thickness,applied pressure and running speed.The test results show that under the loose snow with density of 0.24 g/cm~3,the dynamic friction coefficient of rubber block B with 77.57°angle arrangement is the largest,which is 1.06-1.22 times that of rubber block A(85.75°angle)and 1.19-1.46 times that of rubber block C(59.24°angle).Under loose snow,the coefficient of dynamic friction of rubber block B is 0.453 at a load of 60 N,a snow thickness of 20 mm,and a speed of 360 mm/min.Under dense snow with a density of 0.48 g/cm~3,the coefficient of dynamic friction of rubber block B,which is still arranged at an angle of 59.24°,is 1.04-1.16 times higher than that of rubber block A and 1.10-1.39 times higher than that of rubber block C.1.10-1.39 times higher than that of rubber block C.Under dense snow,the maximum coefficient of kinetic friction of rubber block B was 0.364 at a load of 60 N,a snow thickness of 10mm,and a speed of 240 mm/min.When the test factors were at the same level,the coefficient of kinetic friction under loose snow was slightly higher than that under dense snow.The geometry of the seahorse tail was measured,the seahorse tail was grossly dissected,and its structure was observed and analyzed by sweeping electron microscopy,and it was found that the seahorse tail had 39-41 articular rings,each of which was composed of four diamond-shaped bone fragments.The rings were classified into four categories according to the role they played in the climbing process:the projection of the bony lamellae(spiny convexity),the overlap between the bony lamellae and the bony lamellae,the extension of the bony lamellae on the bony ring to the bony lamellae on the adjacent bony ring,and the bony ribs of the bony lamellae.When the seahorse climbs on the solid-liquid surface,the projection of the bone piece is in direct contact with the solid,which has the effect of increasing friction;the overlapping part is similar to the rotating part,which gives the seahorse tail higher freedom and greater flexibility;the other two structures play the role of support.The engineering bionic idea is adopted to combine the raised part of the seahorse bone piece with the tire tread pattern,and considering that the deformation of the tire will not exceed the range of the Mooney Rivlin intrinsic model,Mooney Rivlin is chosen as the intrinsic model of rubber,and the Abaqus finite element software is used to simulate the pressure-bearing analysis of the bionic tire,which verifies that the bionic tread pattern will not affect the load-bearing performance of the tire.Considering the difficulty of machining,the bionic tires were simplified and machined out using 3D printing technology,and the tires were tested for skid rate test by wheel mechanics test bench.The two bionic tires and the comparison tire were tested under loose snow and dense snow with three test factors:snow thickness,load and speed.The test results showed that bionic tire C with reindeer and seahorse factors had the lowest slip rate,followed by bionic wheel B with only seahorse factors,while comparison wheel A had the largest slip rate,1.07-1.43 times that of tire B and 1.42-1.67 times that of tire C under loose snow;1.24-1.5 times that of tire B and 1.25-1.54times that of tire C under dense snow,it was also found that the increased density of snow increases wheel slip.The damage force to snow particles and the amount of snow lift when the vehicle is driven on a soft road surface can reflect the mechanical properties of the tire,but the limited test conditions make it difficult to analyze the amount of snow variation.Therefore,with the help of EDEM discrete element software,the damage to the snow layer is analyzed from the perspective of snow particles when three kinds of tires are driven on the same thickness of snow layer under the same slip rotation rate.The simulation results show that the bionic wheel raises the least amount of snow,damages the snow layer the least and has the best traction performance.In addition,the simulation analysis of the bionic wheel was also done at 10 mm,15 mm and 20 mm thicknesses respectively,and the simulation results showed that the increase of snow layer thickness would increase the snow lifting and reduce the passing performance of the tire.When the vehicle is driven on the ice and snow road,besides the three factors of load,speed and snow thickness,the slope also has an important influence on the vehicle passability,but due to the limitation of the test conditions,it is impossible to control the ice and snow surface in a regular slope.Therefore,with the help of ADAMS multi-body dynamics software,the slip rate,velocity and ground interaction force of the vehicle body assembled with three kinds of wheels on the ice and snow surface with a slope of2°were analyzed.The simulation found that the vehicle body A with dual bionic factor wheel A had the best passability,followed by vehicle body C with single bionic factor wheel C,and the next best was vehicle body B with contrast wheels.simulation results showed that the displacement of vehicle body A was 1.46 times that of vehicle body B and 1.01 times that of vehicle body C for the same wheel speed and motion time.