共查询到20条相似文献,搜索用时 15 毫秒
1.
通过固液界面摩擦力测试装置研究了微液滴在PDMS软基体表面运动时的动态摩擦学行为,并对微液滴体积、滑动速度及软基体力学性能对固液界面动态摩擦行为的影响进行了分析. 结果表明:微液滴在软基体表面运动时表现出最大静摩擦力和动态摩擦力. 最大静摩擦力与微液滴黏度和速度梯度呈正比,动态摩擦力与微液滴体积、滑动速度和基体力学性能有关. 随着微液滴体积的增加,三相接触线长度增加,动态摩擦力增加;随着相对滑动速度增加,三相接触线长度及接触角滞后增加,动态摩擦力增加;随着软基体弹性模量降低,固液界面黏附力增加,固液界面运动能量耗散增加,动态摩擦力增加. 研究结果可为PDMS软基体表面微液滴的精确驱动和运动参数优化提供理论指导,也可进一步丰富固液界面摩擦理论. 相似文献
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可移动式机器人已成为机器人研究领域的重要分支,为实现其在狭小特殊环境中的运动, 学者们提出并研究了振动驱动移动系统.本文基于二维LuGre摩擦模型和拉格朗日方程,给出了一类振动驱动系统在各向同性摩擦环境中的动力学建模方法和数值算法.这类振动驱动系统结构简单且密封性好,依靠箱体与地面间的摩擦力实现自身的定向运动.该系统由一个外部箱体和两个内部质量块构成,两个质量块在箱体内的两个平行轨道上作三相振动驱动,箱体通过三个刚性支撑足与地面保持接触. 二维LuGre摩擦模型的利用,可有效避免库伦摩擦模型的不连续性给动力学方程的数值求解带来的困难,且可有效揭示该系统在运动过程中的黏滞-滑移切换现象. 数值仿真结果表明,通过调整其内部质量块的驱动参数,可实现箱体的直线平移、定轴转动和平面一般运动,且箱体在移动和转动过程中会出现擦滑、穿滑、回滑和不黏等4种现象; 另外,通过调节驱动参数, 不仅可以改变箱体移动和转动的快慢,还可以改变箱体形心运动轨迹的曲率半径. 相似文献
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可移动式机器人已成为机器人研究领域的重要分支,为实现其在狭小特殊环境中的运动, 学者们提出并研究了振动驱动移动系统.本文基于二维LuGre摩擦模型和拉格朗日方程,给出了一类振动驱动系统在各向同性摩擦环境中的动力学建模方法和数值算法.这类振动驱动系统结构简单且密封性好,依靠箱体与地面间的摩擦力实现自身的定向运动.该系统由一个外部箱体和两个内部质量块构成,两个质量块在箱体内的两个平行轨道上作三相振动驱动,箱体通过三个刚性支撑足与地面保持接触. 二维LuGre摩擦模型的利用,可有效避免库伦摩擦模型的不连续性给动力学方程的数值求解带来的困难,且可有效揭示该系统在运动过程中的黏滞-滑移切换现象. 数值仿真结果表明,通过调整其内部质量块的驱动参数,可实现箱体的直线平移、定轴转动和平面一般运动,且箱体在移动和转动过程中会出现擦滑、穿滑、回滑和不黏等4种现象; 另外,通过调节驱动参数, 不仅可以改变箱体移动和转动的快慢,还可以改变箱体形心运动轨迹的曲率半径. 相似文献
4.
Any linearised theory of the initiation of friction-excited vibration via instability of the state of steady sliding requires information about the dynamic friction force in the form of a frequency response function for sliding friction. Recent measurements of this function for an interface consisting of a nylon pin against a glass disc are used to probe the underlying constitutive law. Results are compared to linearised predictions from the simplest rate-state model of friction, and a rate-temperature model. In both cases the observed variation with frequency is not compatible with the model predictions, although there are some significant points of similarity. The most striking result relates to variation of the normal load: any theory embodying the Coulomb relation F∝N would predict behaviour entirely at variance with the measurements, even though the steady friction force obtained during the same measurements does follow the Coulomb law. 相似文献
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摩擦磨损的扫描电子显微镜原位动态研究,可以跟踪观察磨屑形成和磨痕演变的全过程,以及材料表面在摩擦磨损中变化的真实情况.在由国产台式扫描电子显微镜改装成的滑动摩擦磨损试验装置上,对15#钢-45#钢摩擦磨损过程所作的原位动态研究表明:15#钢在对摩过程中始终存在粘-滑现象,微切削是其主要磨损机理;15#钢磨痕形貌变化可分5个阶段——第1阶段出现与滑动方向垂直的横向裂纹,第2阶段产生大片状剥离,第3阶段产生小片状疲劳剥离,第4阶段产生块状磨屑并形成表面凹坑,第5阶段磨痕趋于平坦.这种滑动摩擦磨损试验装置不仅具有对摩擦磨损过程作动态跟踪观察的功能,而且可用于对摩擦学过程作准动态观察,这两种观察方法对研究摩擦磨损过程同等重要 相似文献
8.
O. S. Sentemova 《Moscow University Mechanics Bulletin》2011,66(6):138-140
The problem of motion of a homogeneous ball on a horizontal plane is considered. It is assumed that the contact patch is of
spherical shape, whereas the pressure center does not coincide with the center of the contact patch and is displaced in the
sliding direction of the ball. The friction force has two components that are parallel and perpendicular to the sliding velocity;
the friction force moment has a vertical component and two horizontal components being parallel and perpendicular to the sliding
velocity. 相似文献
9.
The dynamic behaviors of a dry friction oscillator with shape memory alloy (SMA) are investigated. Motion equations of the system are formulated by the restoring force of the oscillator in terms of a polynomial constitutive model dependent mainly on the temperature. The vibration response of the system and the influence of the temperature are investigated. It is shown that chaotic motions can be observed and dramatically changed by temperature characteristics. Moreover, some sliding bifurcations are also discovered and influenced by the temperature. Compared with conventional dry friction elastic oscillators, the dry friction SMA oscillator presents much richer dynamic behavior caused by pseudo-elasticity, and vibration reduction can be achieved through the shape memory property of SMA restraints. 相似文献
10.
《力学快报》2022,12(5):100355
Holding an object by clamping force is a fundamental phenomena. Layered or laminated architectures with internal sliding features are essential mechanism in natural and man-made structural system. In this paper, we combine the layered architecture and clamping mechanism to form a multilayered clamper and study the clamping force with internal friction. Our investigations show that the clamping force and energy dissipation are very much depend on the number of layers, its geometry and elasticity, as well as internal friction. The central goal of studying the multilayered clamp is not only to predict the clamping force, but also as a representative case to help finding some clue on the universal behaviours of multilayered architectures with internal friction. 相似文献
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Impact friction test method by applying stress wave 总被引:1,自引:0,他引:1
K. Ogawa 《Experimental Mechanics》1997,37(4):398-402
To understand the dynamic response of two bodies in contact, kinetic friction during impact presently is focused on. A new
testing technique, which provides the normal and the tangential impact force independently, is developed by modifying the
split Hopkinson pressure bar method. Normal and torsional stress wave propagation in a one-dimensional framework of an axial
impact of an input tube on a rotating output tube is analyzed and is experimentally verified. Kinetic friction of brass was
clarified at a high rate of sliding up to 5 m/s and is found to be almost constant independent of normal force and sliding
velocity. The present technique provides direct measurement of kinetic friction with simple configuration and data analysis. 相似文献
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Xiao-Dong Pan 《Rheologica Acta》2005,44(4):379-395
In pursuit of a better understanding of the relationship between wet sliding friction and bulk viscoelastic properties of elastomer compounds, especially the contribution from different reinforcing fillers, the linear thermorheological behavior, the nonlinear dynamic moduli under shear deformation (for strain up to about 140%), and the wet sliding friction have been characterized in detail for crosslinked compounds of low-cis polybutadiene filled with different reinforcing fillers including carbon black, graphitized carbon black, and precipitated silica. We examine the scenario of possible extra energy dissipation via higher harmonic excitation in rubber compounds coupled with dynamic deformation consisting of components at many frequencies during sliding of rubber on a rough surface. While no straightforward explanation is identified relating the observed difference in wet sliding friction arising from different fillers to the bulk viscoelastic properties, some unexpected viscoelastic features arising from the compounds are observed. 相似文献
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A finite element study of the deformations, forces, stress formations, and energy losses in sliding cylindrical contacts 总被引:1,自引:0,他引:1
Raghvendra Vijaywargiya 《International Journal of Non》2007,42(7):914-927
This work presents the results of a finite element analysis (FEA) used to simulate two-dimensional (2D) sliding between two interfering elasto-plastic cylinders. The material for the cylinders is modeled as elastic-perfectly plastic and follows the von Mises yield criterion. The FEA provides trends in the deformations, reaction forces, stresses, and net energy losses as a function of the interference and sliding distance between the cylinders. Results are presented for both frictionless and frictional sliding and comparisons are drawn. The effects of plasticity and friction on energy loss during sliding are isolated. This work also presents empirical equations thatt relate the net energy loss due to sliding under an elasto-plastic deformation as a function of the sliding distance. Contour plots of the von Mises stresses are presented to show the formation and distribution of stresses with increasing plastic deformation as sliding progresses. This work shows that for the plastic loading cases the ratio of the horizontal force to the vertical reaction force is non-zero at the point where the cylinders are perfectly aligned about the vertical axis. In addition, a “load ratio” of the horizontal tugging force to the vertical reaction force is defined. Although this is analogous to the common definition of the coefficient of friction between sliding surfaces, it just contains the effect of energy loss in plasticity. The values of the contact half-width are obtained for different vertical interferences as sliding progresses. 相似文献
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高斯原理给出了通过求函数极值、从可能运动中鉴别出真实运动的规则, 它可以使得多体系统动力学问题不需通过求解微分(代数)方程, 而是采用求解最小值的优化方法来解决, 从而提供了一种适用于优化算法的建模思路, 因此, 如何定义恰当的高斯拘束函数是动力学优化方法得以实现的前提. 对于理想系统而言, 约束对系统的作用可以通过约束方程来体现, 故高斯拘束可表达为系统质点加速度的函数, 系统的动力学问题因此可以描述为目标函数为高斯拘束函数、优化变量为质点加速度的约束最优化问题; 当系统中需要考虑干摩擦等非理想因素时, 部分相互作用不能被所定义的约束方程所涵盖而需要采用额外的物理规律来描述, 这种相互作用破坏了原有的针对理想系统的高斯拘束函数的极值特性. 基于变分类的高斯原理, 推导并证明了目标函数以理想约束力所表达的非理想系统的极值原理, 针对目前文献中用于非理想系统的高斯原理进行了讨论, 指出其实际为文中的极值原理在非理想约束力与理想约束力无明显关联时的一种特殊表达形式, 当非理想约束力与理想约束力有明显的函数关系(如库仑摩擦定律中滑动摩擦力与法向约束力间的线性关系)时, 该形式失效; 同时根据文中的极值原理, 得到了考虑库仑摩擦时非理想的多体系统动力学问题的优化模型. 例子中分析了优化模型及相应的线性互补性模型的关系, 分析发现在满足刚体滑动问题的唯一性条件下二者互为充分必要条件, 从而证明了文中优化模型的可靠性; 并采用优化计算方法进行了动力学模拟, 模拟结果显示了将高斯原理与优化算法相结合的可行性及有效性. 相似文献
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高斯原理给出了通过求函数极值、从可能运动中鉴别出真实运动的规则, 它可以使得多体系统动力学问题不需通过求解微分(代数)方程, 而是采用求解最小值的优化方法来解决, 从而提供了一种适用于优化算法的建模思路, 因此, 如何定义恰当的高斯拘束函数是动力学优化方法得以实现的前提. 对于理想系统而言, 约束对系统的作用可以通过约束方程来体现, 故高斯拘束可表达为系统质点加速度的函数, 系统的动力学问题因此可以描述为目标函数为高斯拘束函数、优化变量为质点加速度的约束最优化问题; 当系统中需要考虑干摩擦等非理想因素时, 部分相互作用不能被所定义的约束方程所涵盖而需要采用额外的物理规律来描述, 这种相互作用破坏了原有的针对理想系统的高斯拘束函数的极值特性. 基于变分类的高斯原理, 推导并证明了目标函数以理想约束力所表达的非理想系统的极值原理, 针对目前文献中用于非理想系统的高斯原理进行了讨论, 指出其实际为文中的极值原理在非理想约束力与理想约束力无明显关联时的一种特殊表达形式, 当非理想约束力与理想约束力有明显的函数关系(如库仑摩擦定律中滑动摩擦力与法向约束力间的线性关系)时, 该形式失效; 同时根据文中的极值原理, 得到了考虑库仑摩擦时非理想的多体系统动力学问题的优化模型. 例子中分析了优化模型及相应的线性互补性模型的关系, 分析发现在满足刚体滑动问题的唯一性条件下二者互为充分必要条件, 从而证明了文中优化模型的可靠性; 并采用优化计算方法进行了动力学模拟, 模拟结果显示了将高斯原理与优化算法相结合的可行性及有效性. 相似文献
18.
三方程线性弹性-阻尼DEM模型及碰撞参数确定 总被引:1,自引:1,他引:0
建立了一种考虑法向接触力、切向接触力(含静滑动摩擦力及动滑动摩擦力)和力矩(含由切向力产生的力矩及静滚动摩擦力矩和动滚动摩擦力矩)的三方程线性弹性-阻尼离散单元模型,并将该模型应用到颗粒物料的三维数值模拟中,讨论了模型中几个重要碰撞参数--刚性系数、阻尼系数及摩擦系数的选择及其对计算结果的影响,同时也探讨了时间步长等计算参数对模拟结果的影响.为了验证算法和参数选择的正确性,本文对几个有代表性的颗粒系统进行了数值试验研究,并对计算结果进行了细致的分析,验证了新模型和参数选择的正确性. 相似文献
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纳米MoS2薄膜的浸涂—热解法制备和摩擦学性能研究 总被引:1,自引:1,他引:1
用浸涂 -热解法在玻璃基底表面制备了纳米 Mo S2 薄膜 ,利用 X射线光电子能谱仪、X射线粉末衍射仪、原子力显微镜、静 -动摩擦系数测量仪和扫描电子显微镜等仪器研究了薄膜的微观结构、表面形貌和摩擦学性能 ,初步探讨了薄膜的摩擦磨损机制 .结果表明 :浸涂 -热解法制备的 Mo S2 薄膜由近似非晶的纳米微晶组成 ,薄膜均匀、致密 ,表面粗糙度小 ;在室温干摩擦条件下 ,Mo S2 薄膜与 GCr15钢球对摩时显示出良好的抗磨减摩性能 ;当负荷为 1.0 N而滑动速度为 90 mm/ min时 ,其耐磨寿命大于 5 0 0 0次 ,摩擦系数最低可达 0 .12 .磨损表面形貌显微分析表明 :在低速和低负荷下薄膜的磨损机制主要是塑性变形和轻微粘着转移 ,而在较负荷和速度下的主要磨损机制为塑性变形和严重剥落 相似文献
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We propose a new friction model based on the well known LuGre friction model that can accurately describe the nature of friction force in the gross sliding regime. The modification is based on the responses observed from a single degree-of-freedom friction-induced vibration system. Numerical analysis shows that the friction curve in the gross sliding regime can only show counter clockwise hysteretic loops without violating other essential features. We then develop a new friction model by modifying the LuGre friction model that can describe both clockwise as well as counter clockwise hysteretic loops in the pure sliding domain. 相似文献