Research On Radial Tire Comprehensive Ground Performance Evaluation System And Method

The tires labeling regulation has set requirements of tire quality. It is reported that there are36%of tires produced by Chinese factories cannot meet the standard of the first stage and50%of the tires cannot meet the standard of the second stage of the regulation. The basic reason to the situation is the lacking of independent innovation and tire performance evaluation system. Nowadays tire performance evaluation is mainly according to the test. The relationship between evaluation results and tire structure requires exploring. It is urgent to put forward an evaluation and prediction method of tire ground performance.Tire-ground pressure distribution test is carried out by Tekscan system. Taking a tire as an example, the laws of tire inflation pressure and load affecting the pressure distribution are studied. The results show that the contact area increases linearly with the load. But there is no linear relationship between the contact area decreasing and the inflation pressure increasing.To evaluate tire ground performance, a proper way of describing the footprint characters needs to be put forward. This paper adopts10footprint geometrical indexes and5mechanical characters indexes to describe the tire-ground pressure distribution. Based on the describing method, the software called TFAS (Tire Footprint Analyze System) has been invented. The footprint character indexes can be calculated automatically.Taking the TBR tire385/55R22.5as the study object, the tire-ground pressure distribution is analyzed by finite element method. The mechanical properties of rubber material and steel cord material are studied by experiments. An effective testing method of getting material parameters for FEA is explored. The Yeoh model is chose for describing rubber material and Rebar model is chose for cord-rubber material to establish the FEA model. The validation of the FEA model is proved by tire contour dimensions, load-deflection and tire-ground pressure distribution. The calculation accuracy of the FEA model meets the research needs.Based on the current design cross section and the actual mapping cross section of tire385/55R22.5, FEA models are built to study the law of inflation pressure, load, belt structure, crown arc and contour profile working upon the tire-ground pressure distribution. The conclusions show that the footprint becomes concave with the decrease of inflation pressure and increase of load. This phenomenon often leads to tire tread shoulder early wear. The increase of belt width brings little improvement to footprint while the increase of belt angle makes the pressure of tread shoulder decrease and the footprint becoming rectangle. The tire-ground pressure distribution can be well improved by increasing the belt width and angle at the same time. The crown arc can modify the footprint directly and almost any footprint can be acquired by control the crown arc parameters. The contour profile of cross section has great importance of improving the tire-ground pressure distribution, increasing the contact area and making the contact pressure well-distributed.The tire ground performance is studied by using the virtual test method of simulating tire grip performance, wear performance and rolling resistance. The value of the tangential force is put forward to measure grip performance, the friction energy loss to measure wear performance and the rolling resistance to measure the rolling resistance performance. The results show that normal and tangential forces on tire-ground contact surface both show a center symmetric distribution during static-load condition. While the normal and tangential forces on the contact surface show a similar tendency that the force on tread center moving back and the forces on tread shoulder moving front during the braking condition. Comparing with the static-load condition the stress concentration of the tread shoulder during braking condition is more obvious and the contact area is7%larger. Tire wear happens in the joint action of tangential force and tread slippage. The value of tangential force doesn’t determine the friction energy loss, thus tread wear. During free rolling condition, the rolling resistance increases with the increase of load and decrease of inflation pressure and the forces on tread center becomes even and the forces on tread shoulder is higher.The relation between the tire ground performances and the pressure distribution characters is studied by correlation analysis. The conclusions show that tire with wider tread has better grip performance. The lager the average pressure and the pressure deviation value are, the worse wear performance is. The stiffness of tire has the most important influence on the rolling resistance. On the basis of correlation analysis and the finite element analysis conclusions, the analytic hierarchy process model and judgment matrix of evaluating tire ground performance are built. The method accuracy of building judgment matrix is proved by consistency check. The tire-ground performances of4tires with different structure designs are predicted and evaluated by the evaluation system. The evaluation conclusions show good consistency with the virtual test result acquired from finite element analysis. The conclusions have provided research foundation of completing tire comprehensive performance evaluation system and technique support of improving R&D efficiency of China’s tire industry and tire quality.