Influences of loading and radial stiffness on mechanical elastic wheel enveloping characteristics

To change the situation of the existing tire, developing run-flat and anti-puncture tire to guarantee high performance and security has become a consensus of the world's major tire manufacturers. Therefore, researchers have recently focused their attention on non-pneumatic tires with different structures. But the non-pneumatic tires have the disadvantage of excessive weight, complex processing technology or cooling difficult and so on. Furthermore, the process of manufacturing such tire is still in the stage of research and development. To solve the above problems, a mechanical elastic wheel (MEW) for the off-road vehicle is proposed which is a kind of non-pneumatic tire. The MEW could be realized the basic function of traditional pneumatic tire. In additional, the problems such as stinging, puncturing and blasting damage can be avoided. Thus, the MEW is greatly satisfied with requirements of safe service for the special vehicles, such as military vehicles, off-road vehicles, emergency service and disaster relief vehicle. In this paper, to solve the shock vibration transmission and improve vehicle ride performance when the MEW is running over uneven road, we studied the enveloping characteristics and influencing factors of MEW using the flexible roller contact (FRC) model and the method of the finite element simulation and experiments. The influence of loading and radial stiffness on the enveloping characteristics of the MEW was revealed according to the analysis of the effective road input. Moreover, the reliability of the model was verified. The amplitude of effective road input of MEW decreased with the increase of loading, and the disturbance length increased with the increase of loading. Under this circumstance, the radial stiffness was unchanged. And the amplitude of effective road input of MEW increased with the increase of radial stiffness, but the disturbance length decreased with the increase of radial stiffness under a certain loading. The analytical solution, finite element simulation and experimental results were in excellent agreement for the effective road input. The MEW swallowed the cleat completely when the obstacle was centred under the hub centre, and it behaved as if there were no cleat at all under a certain loading. The results indicated that the MEW had the remarkable characteristics of enveloping cleat, reducing the impact and prolonging the action time when the MEW was running over uneven road. Based on the established finite element model and the bench testing, the enveloping characteristics while traversing the obstacle at low speed was investigated, and the influence of loading and radial stiffness on the vertical dynamic mechanical response were illustrated. The vertical dynamic mechanical response of MEW increased with the increase of radial stiffness under a certain loading. In the low-deflection case, the vertical force curves were similar to a parabola. With increasing deflection, in the medium deflection case, there were two maximums and between them a minimum occurred, the trend was called camel back. The MEW swallowed the cleat completely under a certain loading, which could be called typical static enveloping characteristics. The analysis results reflected the objective law of the actual enveloping characteristics of the MEW, and provided a reference for the MEW structure optimization and the vibration characteristics of the whole vehicle.