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直齿轮传动非牛顿流体瞬态弹流润滑研究 总被引:4,自引:0,他引:4
综合考虑润滑流体的非牛顿特性以及齿轮传动的瞬态效应,采用Bair-Winer粘塑模型推导了非牛顿流体雷诺方程,建立了非牛顿流体瞬态弹流润滑模型;进行直齿轮传动非牛顿流体弹流润滑数值分析,获得了齿轮传动沿啮合线的油膜压力、油膜形状以及摩擦因数的分布。结果表明:在非牛顿流体工况下,油膜厚度、油膜压力以及轮齿表面摩擦因数均有所降低,因此在齿轮弹流润滑研究中应考虑流体的非牛顿特性的影响。 相似文献
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以渐开线直齿圆柱齿轮为研究对象,建立了加入非牛顿和变温因素的齿轮润滑模型。利用多重网格法,得到了啮合过程中节点在不同黏度下的弹流数值解。结果表明,在牛顿等温、牛顿变温和非牛顿变温条件下,对于渐开线直齿圆柱齿轮节点,在乏油和充分供油条件下,压力分布随黏度的增加无明显变化,在牛顿变温条件下,第二压力峰逐渐减小,在非牛顿变温条件下,膜厚分布和中心膜厚随着黏度的增加而变大。 相似文献
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温度的非牛顿效应及其润滑失效机理分析 总被引:4,自引:1,他引:4
本文通过分析温度对粘度的影响建立了润滑剂因温度而产生的非牛顿流体模型。通过对简化问题分析表明:由于温度效应的普遍存在,一般润滑条件下也会表现出十分明显的流体非牛顿化现象。并根据给出的剪应力极值曲线指出了温度引起的非牛顿性可以导致重载条件下的润滑失效发生。 相似文献
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薄壁气体辅助注塑件气体穿透过程的研究 总被引:2,自引:0,他引:2
基于气体穿透实验技术的研究分析,针对气体辅助注射成形中气体穿透气道的复杂过程,对薄壁气辅注塑件沿圆形截面气道穿透推进并形成模壁表层熔体的充模流动过程进行了研究。通过引入合理的简化和假设,建立了反映充模流动压力梯度、材料性能、表层熔体厚度比、非牛顿指数等影响因素的计算穿透速度和时间的数学方程.对气体注射压力、熔体温度、非牛顿指数影响气体穿透充模过程进行了实例数值模拟研究。结果表明,增大气体注射压力,其气体穿透方向所形成的表层熔体厚度比值也增大,降低熔体注射温度和非牛顿指数会增大气体穿透的壁厚值,其值接近国外试验测定值,也比较符合实际的气辅注射成形工艺结果。 相似文献
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润滑剂的温度非牛顿效应及其对润滑性能的影响 总被引:1,自引:1,他引:1
本文通过对润滑剂粘温关系及润滑膜能量方程的分析,揭示出润滑过程中温度使润滑剂表现出非牛顿特性;并将建立的本构方程与连续性方程、运动方程直接联立数值求解。结果表明:有效粘度并不能完全反映温度对润滑性能的影响,实际润滑计算中应考虑温度的非牛顿效应。本文为热流体润滑分析提供了一种新方法。 相似文献
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基于混沌分形的函数发生机构优化综合研究 总被引:1,自引:0,他引:1
混沌分形是动力系统普遍出现的一种现象,牛顿优化技术是重要的一维及多维优化迭代技术,其迭代本身对初始点非常敏感,该敏感区是牛顿优化技术所构成的非线性离散动力系统Julia集,在Julia集中迭代函数会呈现出混沌分形现象,提出了一种寻找牛顿优化迭代函数的Julia点的求解方法,利用非线性离散动力系统在其Julia集出现混沌分形现象的特点,提出了一种基于牛顿优化技术的全局优化新方法,对函数发生的平面四杆机构综合问题中产生的非线性方程的求解表明了该方法的正确性。 相似文献
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Suo T Peng P Feng M Liu H Ai Z Tong S Yang X Qin X 《Microscopy research and technique》2012,75(3):294-299
By investigating the identities, amounts, and distributions of the major components of human gallstones, the formation mechanism of calculi may be elucidated. Using FT-IR specular reflection spectroscopy, the compositions of five common types of gallstones, including cholesterol calculus, bile pigment calculus, cholesterol-bilirubin calculus, mixed calculus, and black stones, were positionally, qualitatively, and quantitatively analyzed. Several organic and inorganic substances were found in human gallstones, including cholesterol, calcium bilirubinate, calcium carbonate, calcium phosphate, and calcium stearate. Among them, cholesterol and calcium bilirubinate were the main components. The amounts of these substances varied in different types of gallstone. The distributions of cholesterol and calcium salts (with the exception of calcium bilirubinate) were also closely associated with location. In the various calculi, the amounts of cholesterol and calcium bilirubinate in the cores, the layered structures outside the cores, and the outer shells were higher than those of other substances. The identities of the major components of calculi were similar in different types of gallstones, but their amounts and distributions were significantly different. The analytical method used in this study, which was able to accurately determine the location, quality, and quantity of the major components of gallstones, would be an effective tool to study the formation mechanism of calculi. 相似文献
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《流体机械》2013,(11)
通过对自然工质R290蒸气珠状凝结传热过程的微尺度特性分析得出,在一定的过冷度、液珠半径和分形维数下,液珠的导热热阻随接触角的增大而增大,促进层的热阻在接触角为90°时最小,气液界面的热阻随着接触角的增大而减小,单个液珠的总传热热阻随着接触角的增大呈现出先减小后增大的变化规律,即存在最佳接触角,在此最佳接触角下,单个液珠的总传热热阻最小,单个液珠的传热量最大,换热表面的热流密度最高。随着液珠半径的增大,最佳接触角减小。随着过冷度的增加和分形维数的增大,换热表面液珠成核中心密度增大,表面的热流密度增加。在一定的过冷度下,液珠半径增大,液珠分布密度减少,分形维数增大,液珠的分布密度增加。在一定的分形维数和过冷度下,随着液珠半径的减小,换热表面的热流密度增大。 相似文献
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Cadmium, zinc, selenium, and copper were administered, singly or in combination, orally or subcutaneously. Experiment I included 32 calves of both sexes; six received Cd (two groups), Zn, Cd, and Zn, and Cd and Se (two groups) and one group was a control. In Experiment II (21 bulls), three were given Cd, Cd, and Cu, and Cd and Zn, respectively, and one group was a control. For light microscopy, in Experiment I the highest amounts of silver granules were present in the samples of liver, small intestine, and vesicular gland of all the exposed groups; in Experiment II the most affected organs were liver, kidney, and small intestine. For electron microscopy, in Experiment I, after administration of Cd and Zn, the highest amounts of granules were seen in the cytoplasm of hepatocytes and cells of the proximal and distal renal tubules and the lowest amounts were found in glandular cells of the pancreas. Administration of Cd and Se resulted in the presence of large numbers of granules in the nuclei and nucleoli of spermatogonies. In Experiment II, ingestion of Cd and Zn in feed led to the appearance of highest amounts of granules in the nucleoli, nuclei, and cytoplasm of cells in testes, kidneys, and pancreas. Following Cd intake, the highest accumulation of granules was observed in the nucleoli of hepatocytes and cells of the proximal and distal renal tubules. Combined Cd and Cu produced the highest number of granules in cells of the proximal and distal renal tubules and in the nucleoli and nuclei of germinal epithelium. 相似文献
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Wang Xiankui 《Frontiers of Mechanical Engineering in China》2007,2(3):251-262
Advanced manufacturing consists of continuity of manufacturing, its broad sense, and the core of the manufacturing process.
The technology of continuous manufacturing is discussed according to both historical and modern perspectives. The relationship
between human development and manufacturing technology is also discussed. Manufacturing is a continuously evolving topic.
It is not only the foundation and means of imagination, conception, the science, and the technology of material change, but
also the expression of national economy, national defense, and the support industries. The broad sense of manufacturing theory,
which extends the concept of manufacturing, is an important development in the 20th century. The sense is analyzed in connection
with design, material forming theory, synthesis of manufacturing technology, manufacturing modes, life cycle of product, hardware
and software, and support environment, etc. At the same time, the core action and the development of the theory and technology
of process is also discussed. At the end of this paper, the development directions of mechanical manufacturing science and
technology are mentioned. 相似文献
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热管废热回收蒸发器在浊水余热回收中的应用 总被引:1,自引:1,他引:0
针对污水的特性,为避免生活污水与热泵工质R22产生交叉污染,从而导致系统不能正常运行的可能性,提出在污水与热泵系统工质R22之间采用一个热管换热器,得出在系统增加了一个热管换热器的情况下,污水流量一定时,热泵制热量,性能系数COP值,热泵系统R22工质蒸发温度,污水废热回收热量随污水进口温度的增大而增大,其中热泵工质蒸发温度的增幅最大,达到65.79%,废热回收热量的增幅最小,为6.8%,污水入口温度一定时,热泵制热量,性能系数COP值,热泵工质蒸发温度,废水回收热量随着污水流量的升高而升高,但是热泵工质蒸发温度的和性能系数COP值的增幅减少,热泵制热量,热管工质蒸发温度以及废水回收热量的增幅缓慢增加. 相似文献
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随着科技的发展和进步,石油、天然气和页岩气等能源已成为全球所有国家的命脉。然而想要拥有足够的能源,就必须具备先进的开采技术,因此钻井泵的发展尤为重要。钻井泵被誉为钻机的“心脏”,对于钻机来说至关重要,而对于钻井泵来说其液力端易损件的使用寿命与钻井泵的工作效率和使用寿命息息相关,因此只有提高钻井泵液力端易损件的使用寿命才能确保钻井泵的正常钻进、较高的工作效率和使用寿命。随着信息技术的发展和各行各业的相互促进与相互影响,在未来钻井泵也会向着信息化、自动化、轻量化、人性化和智能化的方向发展。 相似文献
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以Delta机器人为分析对象,研究了动平台的位置误差模型,并对误差源的耦合特性进行了分析。首先,利用从动臂的位置特性,依据几何空间矢量法,建立了Delta机器人机构误差模型;其次,以数理统计与空间矢量原理为基础,推导出Delta机器人关节间隙误差模型;然后,基于空间有限元理论,在建立系统弹性动力学模型的基础上建立了其柔性误差模型;综合考虑这3种误差源,建立了Delta机器人综合位置误差模型;最后,利用Adams与Workbench联合仿真、Matlab数值计算和FARO激光跟踪仪的现场试验验证了位置误差模型的正确性,并对误差源的耦合特性进行了分析,阐述了方向位置误差与坐标轴方位之间的关系。结果表明,影响Delta机器人动平台位置误差的各个误差源间并不是简单的叠加,而是具有明显的耦合特性,并且动平台方向位置误差会随着坐标轴方位的变化而变化。 相似文献
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针对传统固体反射面机构主反射面型面精度和收拢率较低的问题,设计了一种可展开固体反射面机构。首先,提出4种固体反射面机构可展单元构型并对其机构自由度进行分析,对比分析构型方案优缺点确定构型方案4作为可展单元基础构型,并对其结构和展开原理进行详细设计。通过D-H坐标变换建立该机构可展单元的运动学模型,根据几何约束条件建立机构位置矢量方程,利用向量封闭投影法解出各回转角间的关系,结合MATLAB软件编程对机构的位置、速度和加速度进行分析。应用ADAMS软件建立机构仿真模型,验证了机构运动学分析的正确性。最后根据机构中回转角的限制条件和结构尺寸关系,分析回转角和结构尺寸对可展开固体反射面机构收拢率的影响,确定2.2m可展开固体反射面机构的回转角和旋转角分别为78°和30°,中心圆盘半径、铰支座一孔纵向尺寸、切换连杆横向尺寸、纵向尺寸分别为245,8,40,18mm,收拢率为0.326,从而为可展开固体反射面机构的设计提供参考。 相似文献