Experimental And Numerical Study On Tire Tread Wear Behavior

In the light of the challenging fundamental subject——tire tread wear analysis——which demands urgent resolution in both tire engineering and academic community, a series of research work is carried out in this dissertation including the friction model, abrasion model of tread rubber and numerical solving strategy of wear, initially forming a complete tire tread wear analysis method.In this dissertation, a new pin-on-disk test method is proposed to avoid the structural response resulting from the original test method. The friction coefficient of tread rubber is tested via the proposed method under various contact conditions (including3friction disks,5loads and8speeds). On glass disk, the friction coefficient increases monotonically with the increase of the contact pressure. It decreases sharply in the first place and then levels off when the sliding speed increases. On Alumina60and Alumina180disk, the friction coefficient firstly increases and then decreases with the increase of the contact pressure; it increases firstly and then levels off with the increase of the sliding speed. Thereby a unified friction model is put forward to describe the tread rubber friction behavior under various contact conditions. A finite element model is established to simulate the pin-on-disk test procedure, which verifies the feasibility of the new test method. Meantime the unified friction model is verified by the computed friction forces under various contact conditions including different friction disks, contact loads and sliding speeds. In addition, the cornering rolling of rubber wheel on different friction disks is simulated to further validate the effectiveness of the friction model via the good agreement between the computed lateral forces and experimental results.The wear behaviors of six kinds of rubber on Alumina60disk are tested with LAT100, the test results of which are fitted by a power function abrasion model and the proposed temperature characterization model. The high correlations of the fitted results indicate that the above-mentioned two models are effective. Moreover the test results are numerically evaluated by means of the finite element method. Thereby a complete numerical solving strategy of wear post processing is proposed as follows. Firstly the wear rate and wear direction on the contact surface are calculated by the finite element model which comprises the material model, geometric model, friction model and abrasion model. Then the wear increment length is determined according to the maximum allowable wear depth of the surface elements which acts as a criterion for the mesh update, and the boundary displacement method is used to implement the mesh update after wear. Meanwhile, the automation of aforementioned wear post processing is successively achieved by virtue of the python script in ABAQUS. Furthermore, based on the investigations of the effect of criterion parameter δ on the wear simulation results, an optimal method of the selection of δ is proposed. Thereby the wear behaviors of the rubber wheel under different conditions are simulated. The results show that the worn mass of the rubber wheel increases with the increase of the rolling distance, and that the footprint length as well as the unevenness of contact pressure gradually increases.Based on finite element method and implicit solving strategy of tire dynamics, a steady rolling model is constructed in this dissertation, which is of the axisymmetric tire containing only longitudinal grooves (185/75R14). Aimed at the structural characteristics of axisymmetric tires that contain only longitudinal grooves, a modified boundary displacement method is put forward to implement the mesh update after wear, and the wear direction is determined by means of a partitioned multi-reference point method. Meanwhile, the automation of aforementioned wear post processing is successively achieved by virtue of the python script in ABAQUS. With the help of the unified friction model, the power function abrasion model as well as the wear post processing method based upon the proposed modified boundary displacement, the tire tread wear process in steady rolling is simulated. The preliminary evolution law of tire cross-section profile in the case of tire free rolling is revealed for the first time. The tread wear profile is overall symmetrical with uneven wear degrees manifested in each rib. The maximum wear depth occurs at the inside footprint of the ribs on outer sides whereas the minimum wear depth occurs at the outside footprint of the ribs on outer sides. The evolution of tread contact pressure distribution is also revealed. The unevenness of the contact pressure distribution gradually increases in the wear process, and the region with higher pressure is concentrated in the middle of the footprint. The lateral width of the footprint decreases step by step, while the longitudinal width increases. The effects of tire rolling conditions and tread pattern structural parameters are studied. The results show that the higher the rolling speed, the greater the tread wear rate; the lower the inflation pressure, the greater the tread wear rate; the higher the load, the greater the tread wear rate. The tread wear rate under braking and cornering conditions are much greater than that in free rolling conditions. The tread wear rate decreases as the groove depth decreases, while it remains unchanged as the groove width changes.Based on finite element method and the "implicit to explicit" numerical solving strategy of tire dynamics, a rolling tire model with complex tread patterns (185/75R14) is constructed to successfully simulate the tire cornering rolling at0-30°slip angle range and the tire driving with0-100%slip ratios. Aimed at the structural characteristics of tires with complex tread patterns, a periodic modified boundary displacement method is put forward to implement the mesh update after wear, and the wear direction is determined by means of the node order positioning method. Meanwhile, the automation of aforementioned wear post processing is successively achieved by virtue of the python script in ABAQUS. With the help of the unified friction model, the power function abrasion model as well as the wear post processing method based upon the proposed periodic modified boundary displacement, the tire tread wear process of tires with complex tread patterns in steady rolling is simulated. The preliminary evolution law of the tread profile in the case of tire free rolling is revealed for the first time. The tread wear profile is overall symmetrical with uneven wear degrees manifested laterally and longitudinally in each tread block. The maximum wear depth occurs at the inside footprint of the blocks on outer sides whereas the minimum wear depth occurs at the outside footprint of the blocks on outer sides. The evolution of tread contact pressure distribution is also revealed. The unevenness of the contact pressure distribution gradually increases in the wear process, and the region with higher pressure is concentrated in the middle of the footprint. The lateral width of the footprint decreases step by step, while the longitudinal width increases. Furthermore, the tread wear rate of tires with complex tread patterns is far greater than that of tires containing only longitudinal grooves, approximately3.58times.