Experimental analysis on effect of grouser circumferential angle on motion performance of lunar rover wheel

To guide the design of grouser parameters for lunar rover wheel,the effect analysis of circumferential angle of grousers on motion performance of a rigid wheel was conducted in a laboratory single-wheel test bed with loose sand bin.All tests had been done at a free wheel sinkage.The circumferential angle was varied from 0°,5°,10°,15° to 20°.By the analysis and comparisons of tractive and steering performance between smooth wheels and wheels with different circumferential angle grousers,the results show that the drawbar pull(DP),driving torque(DT) and steering resistance moment(SRM) decrease slightly with the increasing circumferential angle.And chevron grousers are more beneficial to improve the tractive performance than herringbone grousers.In order to evaluate motion performance of wheels with grousers,the evaluation indexes of motion performance are introduced into the experimental results.The results reveal that the optimal circumferential angle is 0°,and the optimum value of wheel slip is 13% from the perspective of saving energy to the similar loose sand in the experiments.

Experimental research on grouser traction of deep-sea mining machine

The traction characteristics of the grouser, cutting the simulative soil of deepsea sediment, with different tooth widths, tooth heights, and ground pressures are studied with traction characteristic test apparatus. A traction-displacement model is obtained by combining the analysis of the cutting mechanism. The results show that the tractiondisplacement curves of grousers with different tooth widths, tooth heights, and ground pressures have the same changing trend, which matches the Wong traction model. Their sensitivity coefficient and shear modulus are slightly fluctuated. Therefore, the average values can be used as the traction model parameters. The maximum traction of the grouser with a two-side edge and a 10 mm tooth width increment changing with the tooth height and ground pressure can be determined according to the grousers with different tooth widths. By combining the traction model parameters, the traction-displacement curve of the grouser with a certain group values of tooth width, tooth height, and ground pressure can be predicted. Therefore, the slip of the mining machine can be prevented to improve the mining efficiency.

Comparing tractive performance of steel and rubber single grouser shoe under different soil moisture contents

Steel and rubber are two kinds of materials which are often used for the tracks of off-road vehicles.The objective of this study was to compare tractive performances of steel and rubber grouser shoes under different soil moisture contents.In this study,the tractive performance of single grouser shoe was predicted by soil parameters and three-dimensional shearing model.The soil used in this study was clay soil,and ten different soil moisture contents ranged from 8.58%to 54.36%were applied for investigation of soil parameters.For each soil moisture content,the penetration test,direct shearing test,density and soil moisture content measurement have been performed to obtain the required soil parameters.The experimental results showed that thrust and running resistance of steel single grouser shoe had similar trends to those of rubber single grouser shoe.The thrust of rubber single grouser shoe was always greater than that of steel single grouser shoe with the increase of soil moisture content,and as well as the running resistance.However,the traction of rubber single grouser shoe had a different trend to that of steel single grouser shoe.The traction of steel single grouser shoe was always greater than that of rubber single grouser shoe at any given moisture content except at the stage of less than 15%moisture content.From the experimental results,it can be concluded that the steel single grouser shoe performed better than rubber single grouser shoe in traction for the soil used in this study.

Effects of soil mechanical properties on the height and tractive performance of rubber grouser at different moisture contents

Rubber tracked vehicles are commonly used on agricultural machinery that perform agricultural operations such as rice harvesting in soft paddy fields with low bearing capacity.Research was carried out to assess the influence of soil moisture content and mechanical properties on the tractive performance of a rubber grouser with three heights(45 mm,55 mm,60 mm).The direct shear test and penetration test were used in this study,which was based on a semi-empirical approach of determining tractive parameters.Direct shear tests were used to measure soil shear strength parameters such as cohesion,adhesion,internal and exterior friction angles.The results of the penetration test were used to determine tractive parameters such as soil thrust,running resistance,and traction,for the penetration test,a device was designed and developed.The experimental results revealed that soil cohesion and adhesion increased linearly with increasing soil moisture content,however adhesion dropped after 30.7%.Similarly,the soil thrust initially increased till 21.5%then decreased.Furthermore,running resistance had a decreasing trend over soil moisture content whereas maximum traction achieved for 45 mm grouser height at 21.5%moisture content.It was concluded that a rubber grouser with 45 mm height had better traction rather than 55 mm and 60 mm,it can be suitably used for designing a track system for a crawler vehicle(e.g.,harvester)leading to its greater adoption among the farmers.

月球车沙地行驶动力学建模与仿真

提出建立刚性车轮在松软路面行驶的动力学模型的新方法。该方法对车轮进行离散化处理,基于沉陷理论、剪切理论和被动土压理论预测轮壤接触表面的相互作用力,从而可以对车轮表面的应力分布以及电动机转矩进行分析。进一步地将子模型整合到主副摇臂月球车悬架系统中,建立在松软干砂表面行驶的动力学模型。通过仿真,对移动系统中各个车轮表面的应力分布以及驱动电动机转矩进行分析。为验证模型的正确性,开发了信号处理模块和主副摇臂移动系统试验平台,开展主副摇臂月球车移动系统在干沙表面的移动性能试验研究,对仿真和试验中的车轮功耗以及滑移率进行比较。结果表明主副摇臂移动系统动力学模型具有较好的可信性,该建模方法可以用于高效率的多轮多轴月球车的动力学分析。

基于贝克理论履带沉陷性能研究

地面力学是研究车辆与地面相互作用的边缘学科,履带-地面相互作用是其中较为重要的一个分支。经过对地面力学的研究与总结,发现履带车辆在松软土壤上行驶时,应该采用大履刺履带行走机构,但目前学者们往往忽视了履刺的作用,进行的研究工作较少。基于贝克理论和研究方法,应用力学平衡方法,提出松软土壤条件下大履刺履带压力-沉陷的关系式。采用赋值法解决变形系数为非整数时沉陷量的预测问题。可为大履刺履带车辆沉陷性能和履带结构参数优化提供理论依据。

滑移线连续和平稳分布的变径车轮设计

基于轮地接触动力学理论,设计出一种适应沙壤土环境、具有内外双层紧贴刚性轮片和中部轮刺的新型变径车轮。分析了变径轮不同断面与土壤的作用机理和土壤流动滑移模型,通过对滑移线公式详细推导和数值计算,获得其滑移半径和等效轮周的变化规律,提出了以断面高度为主、倾角为辅的设计思想。建立了满足平稳和连续滑移线模型的剪切滑移交错层断面(可调轮刺)高度与倾角和变径比的函数关系。

基于有限元的岩石型推土机履带板优化设计

介绍了岩石履带板与传统履带板结构特点,分析了目前岩石型推土机履带板易磨损寿命短的原因。针对分析结果,对结构进行优化设计,得到新结构岩石型履带板,并建立了三维模型。基于正常行驶和在冲击载荷作用下两种工况,对两种履带板的受力进行了计算,并应用有限单元法对两种履带板在两种工况下的强度进行了分析,得到了最大应力和最大位移及发生位置。强度分析结果表明,新结构履带板最大应力和最大位移均有所降低,新履带板能适应岩石型推土机的作业需求,为同类型履带板的开发、改型提供了借鉴依据。

履带机器人地面力学研究进展

履带机器人具有高机动性和良好的越野能力,被广泛应用于军事、农业、建筑等领域,基于地面力学研究履带机器人的牵引性能、行驶阻力、越障能力具有重要意义。在车辆地面力学的发展中,针对履带与地面相互作用机理提出了很多研究方法,文中对其中的纯经验法、半经验法、模型试验法和数值分析法进行归纳分类和对比分析;对基于这些方法建立的评价机器人通过性的地面响应模型和影响牵引力的履刺效应模型进行总结,其中地面响应模型重点介绍了压力沉陷模型和剪切应力位移模型;最后,对履带机器人地面力学目前存在的问题做出了分析与讨论,给出了未来可能的研究方向,旨在为后续的研究提供参考与借鉴。

履带板结构对车辆通过性能的影响

履带车辆行驶于极其松软的路面时，其履带板的结构对车辆的通过性能会产生重要的影响；因此改变履板的结构参数是提高履带的推进性能和通过能力的有效途径；而一些文献得出履刺厚度的增加使车辆的行驶阻力显著增大，履刺高度的增加会使行驶阻力略微增加；牵引力随履刺高度的增加而增大，但也会增加行驶阻力；以单位重量的挂钩牵引力作为评定车辆软土通过性的标准，采用贝克方法分析履刺高度，履带板厚度对车辆通过性能的影响；得出履刺高度介于4～6 cm时能够提高车辆的通过性能。

土壤静止侧压力系数引入合理性研究

土壤静止侧压力系数是指土体在侧向不允许变形条件下固结后的侧向有效应力与垂直有效应力之比。以现有的考虑履刺效应的普通履带与土壤相互作用模型和引入土壤静止侧压系数的模型对比,探求土壤静止侧压力系数引入的合理性,为间隔式履带板与土壤相互作用三维模型的建立做理论支撑。

某水泥专业码头创新设计要点

在传统的浮码头散货工艺系统基础上,结合水文、地质条件,提出了浮式钢引桥皮带机方案,即采用浮趸替代升降架,将钢引桥直接固定在浮趸上,利用水的浮力自动升降浮趸及钢引桥,将趸船、多个浮趸、多跨钢引桥及钢引桥上皮带机串联成一整套的浮式结构。

链斗式采金船桩柱的断裂与修复

在我国的采金船生产过程中,已发生过多起定位桩柱的断裂事故.为查明断裂原因,避免意外停船,本文就某采金船的桩柱断裂一例,分析产生事故的原因并确定修复方案.

采金船桩柱的合理分析法

针对采金船设计中桩桩沿船体纵向受力简化分析祛的缺点，提出了合理的分析法．应用推出的公式，可避免繁琐的超静定结构分析过程，立即求得结果。通过实例分析，计算桩拉赘余力矩的当量长度值η，对影响η值的四个计算因子进行分析对比，给出弹簧装置变位与桩柱整体弯曲变形之间的的关系和相互的影响；指出本法的优点，不仅在于桩柱的受力分析上，而且能合理地分析确定整个桩柱系统的变形，为桩柱系统的整体优化设计的分析奠定了基础．

单齿履带板锻造工艺研究和模具开发

大节距260 mm单齿履带板属于异形薄板类锻件,是履带式工程机械车辆行走系统的关键部位。经过对产品特点的分析,提出了大节距单齿履带板锻造过程的工艺开发,在试验后确定了模锻工艺方案。根据产品锻造过程中受力情况和金属流动规律,设计开发出"预锻制坯"的半开半闭式模具和"终锻成形"的闭式模具,完成对单齿履带板的锻造生产。检测结果表明,锻件成形效果好,尺寸达到图纸要求,质量稳定,能够满足生产使用要求。