【作者】 李兵；

【导师】 夏源明； 李子然；

【作者基本信息】 中国科学技术大学 ， 固体力学， 2008， 博士

【摘要】 鉴于轮胎技术的发展,人们越来越认识到胎面花纹的重要性,计及复杂胎面花纹的轮胎结构有限元分析技术越来越受到工程和学术界的关注;由于难度很大,相关的文献至今仍较为罕见,因此发展计及复杂胎面花纹的高效的轮胎有限元模型及其求解策略成为当前工程与学术界的挑战性课题。本文就是在这一背景下围绕着这一课题展开的。基于组合模型技术和两种映射方法,分别提出了组合周向保角映射建模法和组合类保角映射簇建模法。两种建模方法均使繁琐的手工建模过程大大简化,能够较方便地模拟复杂的胎面花纹形态,并得到完全的、较高质量的六面体网格。使用组合周向保角映射建模法建立了用于静力学分析的数个均分的组合花纹轮胎模型和非均分的组合花纹轮胎模型;使用组合类保角映射簇建模法建立了用于稳态滚动分析的数个周期性的组合花纹轮胎模型和变节距的组合花纹轮胎模型;并形成了从装配、充气、静负荷、自由滚动到驱动、制动、侧倾滚动和侧偏滚动等工况下的轮胎结构分析策略。通过较充分的对比考评表明,非均分的组合花纹轮胎模型和变节距的组合花纹轮胎模型是最有效的,可以在求解精度基本相同的前提下大大提高计算效率。在上述基础上,对充气、静负荷、自由滚动、驱动、制动、侧倾滚动和侧偏滚动等工况下的半钢子午线轮胎结构力学特征进行了较系统的分析研究。较系统地揭示了半钢子午线轮胎骨架结构的受力特征。充气压力和负荷的改变没有影响充气工况和静负荷工况下的轮胎骨架结构受力分布的总体特征;自由滚动工况下的受力分布与静负荷工况基本相同,轮胎接地端附近的胎体层帘线、带束层帘线和胎圈钢丝中均出现了不同程度的受压情况;在驱动和制动工况下的受力分布与自由滚动工况比较接近;在侧倾滚动和侧偏滚动工况下轮胎骨架结构受力分布呈现出明显的左右不对称性,帘线轴力的最大值大幅增加,同时受压情况也更加严重。较系统地揭示了半钢子午线轮胎橡胶结构的受力变形特征。各种工况下轮胎橡胶的可能危险区域均集中于胎冠部、胎肩部和胎圈部:与充气工况相比,静负荷和自由滚动工况下的橡胶受力变形情况更加复杂,接地端的可能危险区域内的应力应变水平大幅提高;在驱动和制动工况下,轮胎胎面体部分橡胶的受力变形情况与自由滚动工况有比较显著的差异,同时花纹块在接地面附近的区域成为新的可能危险区域;在侧倾和侧偏工况下,尤其是侧偏工况下,轮胎橡胶的受力变形情况与自由滚动工况的差异非常显著,在轮胎一侧的主体部分橡胶的应力应变水平明显增高,同时花纹块底部、胎侧部和胎圈部均出现了新的可能危险区域。揭示了帘线角的改变对半钢子午线轮胎结构静力学性能的影响。轮胎径向刚度随帘线角的增加而减小,并在帘线角超过某一数值后急剧减小;胎肩部橡胶内危险区域的剪应力、Mises应力和应变能密度等力学量随着帘线角的增加先增加后减小。此外,带束层帘线沿横向变角度铺设的轮胎模型的分析结果表明,这种轮胎具有较好的力学性能,在保证了较高的径向刚度的同时,改善了带束层帘线和胎肩部橡胶的受力状况。初步地揭示了胎面花纹对充气、静负荷、自由滚动和侧偏滚动工况下的子午线轮胎结构受力变形特征,自由滚动和侧偏滚动工况下的轮胎接地性能,以及侧偏滚动工况下的轮胎力学特性的影响。就轮胎结构的受力变形特征而言,横向花纹和纵向花纹对各种工况下的胎面体部分的橡胶受力变形情况均有明显的影响;尽管胎面花纹没有改变轮胎主体部分橡胶的应力应变场的总体分布特征,但是对各个危险区域的应力应变水平均有不同程度的影响;对轮胎骨架结构受力分布的影响较小。就轮胎接地性能而言,纵向花纹和横向花纹的存在使轮胎的接地包络面面积、接地压力水平以及接地压力分布的不均匀性均有所增加。就侧偏力学特性而言,纵向花纹和横向花纹的存在使轮胎的侧偏刚度及回正刚度均有较明显的降低,临界侧偏角则略有增加。综上所述,只有计及复杂胎面花纹的轮胎结构有限元分析才能给出更为准确可靠的结果。更多还原

【Abstract】 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.更多还原