共查询到17条相似文献,搜索用时 171 毫秒
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为探索土壤微形貌加工过程中从动型铲板式触土部件与土壤的互作机理,该研究基于离散元法(Discrete Element Method, DEM)与多体动力学(Multi-Body Dynamics, MBD)耦合算法建立铲板式滚动触土部件与土壤互作的离散元模型。通过EDEM-RecurDyn联合仿真探索滚动部件作业机理,以机具作业速度(0.6、1.0和1.4 m/s)为影响因素,求解机具作业所需水平牵引力与土壤微坑容积,并通过开展台架试验评价仿真模型准确性。耦合仿真结果表明:随机具作业速度的上升,x向水平牵引力和z向垂直力不断变大;机具在不同速度作业下的土壤表面形成的微坑容积分别为3 310.91、3 325.96和3 384.47 mL;根据土壤压缩力、颗粒流向及动能变化,阐释了铲板式滚动触土部件作业过程中土壤微形貌的形成机理。将台架试验与仿真求解结果进行对比,x方向水平牵引力相对误差分别为5.01%、4.58%、4.10%,土壤表面微坑容积误差分别为6.23%、7.09%、5.64%,各作业速度下仿真模型具有较好的准确性。该文所构DEM-MBD耦合模型可为探明铲板式滚动触土部件与土壤互作机理、机具几何结构优化、以及作业参数选择提供理论依据和技术参考。 相似文献
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耕整播农机装备是影响中国耕地耕种作业质量与效益的关键农机装备,随着农业机械化的快速发展,耕整播农机装备对其配套的旋耕刀、犁铧、深松铲、耙片、开沟器等触土部件耐磨性和使用寿命提出了更高的要求。该研究系统分析了触土部件主要的磨损失效形式及磨损机理,综述了提高触土部件耐磨性常用的表面熔覆、表面堆焊处理、表面热喷涂、激光表面强化处理、化学热处理、钎涂等表面处理工艺,从磨损机理、材料研发、结构设计和制造工艺4个方面对比分析了国内外技术差距,针对现阶段耕整播触土部件失效机理、材料、结构、工艺等短板环节的难点问题,展望农机触土部件未来研发方向,拟为表面耐磨强化的相关研究和工程应用提供理论依据与技术支撑。 相似文献
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基于亚塑性本构模型的土壤-触土部件SPH互作模型 总被引:1,自引:1,他引:0
触土部件是农机的主要组成部分,高精度的土壤-触土部件互作模型对农业耕作触土部件的节能优化设计具有重大意义。为提高土壤切削过程数值模拟的精确度,该研究基于光滑粒子流体动力学(Smoothed Particle Hydrodynamics,SPH)框架,从土壤亚塑性本构模型出发,结合土壤-触土部件接触模型,提出一种土壤-触土部件互作模型。通过砂土坍塌试验和土壤切削试验,对比分析了模拟仿真和物理试验中砂土自由表面演变、内部应力变化、土壤静止和运动分界面形态以及粒子位移。在此基础上对4种不同形状刀具的土壤切削过程进行模拟,以土壤切应力、位移分布表征刀具在切削过程中对土壤的破坏情况,讨论了大半径抛物线型刀具切削过程中的土壤粒子速度场,并得出不同形状刀具切削阻力的变化规律。结果表明,刀具水平切削阻力的模拟值和试验值平均相对误差为9.885%,说明所提模型对刀具水平切削阻力的预测精度较高。研究结果可为土壤-触土部件互作模型的建立提供新的思路,为触土部件的优化设计提供参考。 相似文献
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利用正交试验设计理论,研究了试验因素(如土壤水分、载荷作用时间)及其交互作用对土壤在超高分子量乙烯(UHMWPE)及其基复合材料及45钢,表面粘附力的影响,得到了粘附力与试验影响因素的回归方程。研究结果表明:在所考察的试验因素中,含水量对粘附力的影响最大,其次为土壤载荷和载荷作用时间。各影响因素对土壤在不同材料表面粘附的影响程度不同。研究结果同时表明:各因素间的交互作用对不同材料的土壤粘附力影响不 相似文献
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为了揭示超声波高频振动条件下农机触土部件与土壤的相互作用力学特性,构建了该条件下农机触土部件运动理论模型,基于所建模型,分析了高频振动条件下触土部件与土壤间相互作用中的接触分离条件和冲击碎裂效应,理论上解析了超声波振动条件下触土部件碎土与降阻机理。设计建立了超声波振动触土部件土槽试验系统,试验研究了超声波高频振动条件下触土部件工作阻力和碎土特性。试验结果表明,超声波振动激励下,触土部件工作阻力比无振动状态明显降低,土壤硬度越大,其降阻率越高,当土壤硬度由1 MPa增加到4 MPa时,降阻率从22%上升到43%;在土壤含水率15%~30%范围内,含水率越低,降阻率越大,当含水率超过30%后,随含水率的增加,降阻率略有增大。由于超声波高频振动激励下工作的触土部件对土壤的冲击碎裂和能量传递作用,能够使其瞬时工作阻力的波动稳定性得到改善和获得更强的碎土作用。在土壤硬度为1 MPa时,工作阻力的波动稳定性改善不显著,随土壤硬度的增大,工作阻力波动度降低率明显增加,当土壤硬度为2.5和4 MPa时,对应工作阻力波动度降低率达37.1%和54.3%。该研究可为高频低幅振动农机触土部件应用方案的实施提供技术支撑。 相似文献
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推土板的仿生分形设计 总被引:4,自引:0,他引:4
大量的仿生几何非光滑触土部件减粘降阻的试验研究结果表明,触土部件表面上的几何非光滑结构单元的分布对其减粘降阻效果具有显著的影响[1]。该文利用蜣螂体表几何非光滑结构单元(GUSU)分布的生物信息,进行了推土板仿生分形设计并对所设计的推土板进行了推土试验。利用试验优化设计技术,初步考察了推土板上几何非光滑结构单元的分布对推土阻力的影响 相似文献
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Xian Jia 《Biosystems Engineering》2004,87(4):489-493
The adhesion force of soil to solid materials is composed of intermolecular forces, water ring attraction and an attraction force of the water film between the soil and solid materials. The intermolecular attraction of soil adhesion was derived from Lifishitz's intermolecular attraction theory between two macro-objects. The water ring attraction of soil adhesion was based on the energy in the soil adhesion system consisting of soil, solid materials and their interfaces, which can more effectively reveal the rules of soil adhesion when the contact angle of water on the solid materials surface changes from 0 to 180°. The relationship between the attraction force of the water film and the thickness of water film was analysed. 相似文献
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O. Popovic Å.R. Almås M. Manojlovic S. Muratović 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(8):730-738
Abstract Three thermal power plants in Serbia, Croatia and Bosnia of the Western Balkan region were expected to be metal polluting sources, and this study was performed to investigate the bioavailability and chemical speciation of trace metals in soils and soil water extracts, respectively. Surface (0–15 cm) soil samples along with maize and grass samples were collected at a gradient from the pollution source. The chemical speciation of metals was conducted using the Windereme Humic Aqueous Model (WHAM)/Model VI for water, whereas the Diffusion Gradient in Thin Films (DGT) technique was used to estimate plant availability. The chemical speciation indicated that more than 99% of all four metals in soil water extracts were complexed to fulvic acid. This is connected to relatively high soil pH (> 6.5) and high contents of soil organic matter in these soils. The accumulation of trace metals by DGT was not correlated to plant uptake. This is connected to the very low partitioning of free ions in solution, but also to the low variation in metal solubility and metal concentration in plant tissue between sites. In spite of active thermal power plants located in the areas, hardly any differences in concentration of soil metals between sites were seen and the partition of metals in soil waters was insignificant. The latter indicates that these soils have a large metal-retaining capacity. The only significant soil chemical variable affecting the variation in metal solubility was the soil pH. In a time with large infrastructure and industrial expansion in these areas, this investigation indicates the importance of protecting these high-quality soils from industrial use and degradation. High industrial activity has so far had insignificant effect on soil quality with respect to bioavailability of trace metals in these soils. 相似文献