Finite Element Structural Analysis For Radial Tires With Complex Tread Patterns Considered

With the development of tire technology, more people have recognized the importance of tire tread patterns. And Finite Element Analysis (FEA) for radial tires with complex tread patterns considered draws focused attention from the engineering and academic fields. However, relative literature is fairly rare since it is a very difficult problem. How to develop an efficient finite element tire model with complex tread patterns and the corresponding solving strategy becomes a challenging subject in tire technology. In such a condition, this dissertation presents a systematic research on the above problems.Based on the combined modeling technique, two modeling procedures with different mapping method, circumferential conformal mapping and quasi-conformal mapping cluster, are given respectively. Both procedures can not only greatly simplify the awkward manual modeling process for detailed tread patterns, but also easily obtain integrated, high-quality hexahedral meshes. Several uniform and non-uniform combined patterned tire models for static analysis are established with the former procedure. Several combined patterned tire models with constant pitch lengths and with varied pitch lengths, which are used for steady rolling analysis, are established respectively with the latter procedure. The FEA solving strategy of tire structure is founded, with the cases of assembly, inflation, static loading, free rolling, traction, braking, inclination and cornering. The evaluation for the four kinds of models shows that the non-uniform models and models with varied pitch lengths are most efficient and can achieve accurate numerical results.Based on the above models, FEA calculations of the semi steel Passenger Car Radial tire (PCR tire) structure are carried out in the cases of inflation, static loading, free rolling, traction, braking, inclination and cornering, and systematic study on the mechanical behavior of the tire structure is carried out.The load and deformation characters of the skeleton structure of the semi steel PCR tire is revealed as follows. The variation of inflation pressure and vertical load hardly affect the overall features of the load distribution in the skeleton structure in the cases of inflation and static loading respectively. The load distribution in the free rolling case is almost the same as that in the static loading case. For example, the carcass cords, belts cords and bead steel wires near the tread-ground zone are under compression in both cases. Comparing with the free rolling case, the load distribution of the traction case and the braking case is mostly the same, while inclination case and the cornering case are quite different. In the latter two cases, the distribution is distinctly asymmetric, the maximum cord tension increases significantly, and the compression status exaggerates intensely.The load and deformation characters of the rubber structure of the semi steel PCR tire is disclosed as follows. Dangerous regions in the rubber structure congregate in the crown area, the shoulder area and the bead area. Comparing with the inflation case, the stress and strain distribution is more complicated in the cases of static loading and free rolling complicate. Also the stress and stain levels are higher in the dangerous regions. Comparing with the free rolling case, the mechanical behavior of tire tread rubber is quite different in the cases of traction and braking, and additional several dangerous regions appear in the bottom of some tread rubber blocks. In cases of inclination and cornering, the stress and stain level increases distinctly and some additional dangerous regions emerge in the bottom of some tread rubber blocks, in the sidewall area and in the bead area.Effect of belt angle on the static mechanical behavior of the radial tire is discussed as follows. The calculated results indicate that tire radial deformation under inflation and vertical deformation under static load decrease with the increase of the belt angle. However, at the probably dangerous area in tire shoulder, some important parameters such as shear stress, Mises stress and strain energy density, vary non-monotonously with the belt angle and will reach maximums at a critical angle. In addition, the model with non-uniform belt structure has a perfect performance, with a high vertical rigidity and relatively low shear stress, Mises stress and strain energy density in tire shoulder.Influence of tread patterns on the load and deformation characters of the radial tire structure in cases of inflation, static loading, free rolling and cornering, on the tire/road contact behavior in cases of free rolling and cornering and on the cornering properties are summarized as follows. In regard to the load and deformation characters, the longitudinal and lateral grooves have extraordinary effect on the mechanical behavior of the tire tread rubber, have some effect on the stress and stain level in the dangerous regions in tire rubbe, and have little effect on the load characteristic of the skeleton structure. In regard to the contact behavior, the existence of the longitudinal and lateral grooves increases the enveloping contact area, the contact pressure level and the inhomogeneity of the contact pressure distribution. In regard to the cornering properties, the cornering stiffness and the aligning stiffness decrease obviously with the addition of the longitudinal and lateral grooves, while the critical slip angle increases slightly.In conclusion, only when the complex tread patterns are considered can the finite element analysis for the radial tire structure give more precise results.