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51.
The effect of velocity on rigid wheel performance 总被引:1,自引:0,他引:1
A simulation model to predict the effect of velocity on rigid-wheel performance for off-road terrain was examined. The soil–wheel simulation model is based on determining the forces acting on a wheel in steady state conditions. The stress distribution at the interface was analyzed from the instantaneous equilibrium between wheel and soil elements. The soil was presented by its reaction to penetration and shear. The simulation model describes the effect of wheel velocity on the soil–wheel interaction performances such as: wheel sinkage, wheel slip, net tractive ratio, gross traction ratio, tractive efficiency and motion resistance ratio. Simulation results from several soil-wheel configurations corroborate that the effect of velocity should be considered. It was found that wheel performance such as net tractive ratio and tractive efficiency, increases with increasing velocity. Both, relative wheel sinkage and relative free rolling wheel force ratio, decrease as velocity increases. The suggested model improves the performance prediction of off-road operating vehicles and can be used for applications such as controlling and improving off-road vehicle performance. 相似文献
52.
The phase-space kinetic theory for polymeric liquid mixtures is used to obtain an expression for the polymer contribution to the thermal conductivity of a nonflowing, dilute solution of polymers, where the polymer molecules are modeled as Fraenkel dumbbells. This theory takes into account three mechanisms for the energy transport: diffusion of kinetic energy (including the Öttinger-Petrillo term), diffusion of intramolecular energy, and the work done against the intramolecular forces. This paper is an extension of previous developments for the Hookean dumbbell model and the finitely-extensible dumbbell model. A comparison among the dumbbell results suggests that the thermal conductivity increases with chain stiffness. In addition, the zero-shear-rate viscosity and first normal-stress coefficient are also given for the Fraenkel dumbbell model.Dedicated to Prof. John D. Ferry on the occasion of his 85th birthday. 相似文献
53.
54.
B. Hinkelmann 《Rheologica Acta》1982,21(4-5):491-493
From literature some representative equations have been compiled describing the influence of filler on the viscosity of polymer melts. By application of these on the experimental results obtained from GF-SAN it was found that the relative viscosity
R
, i.e. the ratio of the viscosities of the filled and unfilled melt, shows a pronounced dependence on the shear rate
but not on the shear stress. Defining
R
with constant and not with constant
(as it is usually done), an analytical approach is possible independent of
Further the influence of pressure, temperature and filler content on the zero-shear viscosity of filled polymer melts may be expressed by a modified Arrhenius equation. 相似文献
55.
介绍了用恒流法自制仪器精确测定液体的粘滞系数.该自制仪器,能有效地保证底部的密封性、液体水位恒定和可操作性,还增设一个玻璃管连通器,附加一根标尺和游标使液体水位的测量精确度提高.并在接毛细管输出液体的量筒处加上光电计使测量液体流速的精确度提高,采用该仪器测定了水和乙醇两种液体在变温条件下的粘滞系数,经实验比对,所测得结果与理论值能较好地吻合.同时设计了可调换不同管径的毛细管,能快速准确地测量多种变温液体的粘滞系数. 相似文献
56.
Jialai Wang 《Journal of the mechanics and physics of solids》2004,52(4):891-905
An improved method based on the first-order shear deformable plate theory is developed to calculate the energy release rate and stress intensity factor for a crack at the interface of a bi-layer structure. By modeling the uncracked region of the structure as two separate Reissner-Mindlin plates bonded perfectly along the interface, this method is able not only to take into account the shear deformation in the cracked region, but also to capture the shear deformation in the uncracked region of the structure. A closed form solution of energy release rate and mode decomposition at the interface crack is obtained for a general loading condition, and it indicates that the energy release rate and stress intensity factor are determined by two independent loading parameters. Compared to the approach based on the classical plate theory, the proposed method provides a more accurate prediction of energy release rate as well as mode decomposition. The computational procedures introduced are relatively straightforward, and the closed form solution can be used to predict crack growth along the layered structures. 相似文献
57.
58.
This study focuses on the development of a methodology for the determination of some in situ parameters for off-road vehicle mobility on sandy soils. The stress field in the vicinity of and at the interface between a wedge and soil was determined by solving the stress equations using the method of characteristics. The governing equations were solved numerically by using backward finite difference method. The proposed method allows the prediction of any two of the in situ soil parameters δ, φ, and γ (respectively, the interfacial friction angle between the material of a wedge penetrometer and the soil, the internal friction angle, and the unit weight of the soil), given the value of any one of them and the results of penetration tests of two different apex angle wedges. The predictions and the measured values are in agreement. 相似文献
59.
60.
A method for the detection of small masses with the aid of a longitudinally vibrating band is described and further applications, e.g. for viscosity and humidity measurement are discussed. The complex Young's modulus of the band can also be determined. 相似文献