PRECISE MEASUREMENT AND ANALYSIS OF BASIC ELEMENTS OF TRAVELING PERFORMANCE OF WHEELS

为了研究越野车辆的行驶性能，过去研制了各种类型的测量软土地基上行驶性能的力学量的装置。然而，它们还没有达到令人满意的精度，同时很难向车轮提供驱动扭矩，从而保持车轮与土壤之间的恒定接触载荷。本研究研制了一种高精度测量车轮在恒定接触载荷作用下的基本力学量，即扭矩、接触载荷、拉杆拉力、车轮表面的法向应力、切向应力以及土体变形的仪器。这些量中的大多数都可以在在线计算机显示器上可视化。在此基础上，编制了基于弹塑性子加载面模型的有限元程序，分析了刚性车轮转动对土体变形的影响。该程序的主要特点是适当地分析了土体的弹塑性变形，真实地描述了车轮与土壤接触面的边界条件，并结合库仑摩擦定律，自动保持接触载荷不变。此外，它由两个阶段组成，即轮子垂直下沉的下沉阶段和轮子滚动行进的滚动阶段。计算结果与试验数据的对比表明，该程序的分析结果可以定性地描述试验数据的总体趋势，但对车轮行驶性能的定量预测需要进行修正。

In order to study the traveling performance of off-road vechicles, various types of apparatus measuring mechanical quantities of a traveling performance on a soft ground have been developed in the past. They have not achieved, however, a satisfactory accuracy as yet, while it is difficult to provide a driving torque to a wheel, maintaining a constant contact load between a wheel and soils. In this study, a new apparatus was developed, which is capable of measuring the basic mechanical quantities, i.e. torque, contact load, drawbar-pull, normal and tangential stresses on the wheel surface and the deformation of soil under a constant contact load with high accuracy. Most of these quantities are visualized on an on-line computer display. Further, a finite element program based on the subloading surface model of elasto-plasticity has been developed to analyze the soil deformation by the rotation of a rigid wheel. The main features of this program are to analyze suitably the elastoplastic deformation of soil, to describe realistically the boundary condition at the contact surface between the wheel and the soil, incorporating the Coulomb's friction law, and to keep the contact load constant automatically. Besides, it consists of two stages, i.e. the sinkage stage in which a wheel goes down vertically and the rolling stage in which a whee travels rolling. The comparison of the calculated results with the test data verified that the analysis by this program can describe qualitatively the general tendency of the test data but is required a modification for the quantitative prediction of traveling performance of wheel.