There are a number of widely used machine components, such as rolling element bearings, gears and cams, which operate in the lubrication regime known as Elastohydrodynamics (EHD), where lubricant film thickness is governed by hydrodynamic action of convergent geometry, elastic deformation between non-conformal contacting surfaces, and the increase of lubricant viscosity with pressure. Variable loading conditions occur not only in all the machine components mentioned above, but also in natural joints such as hip or knee joints of humans or many vertebrates. Experimental studies of the behaviour of EHD films under variable loading are scarce and to authors’ knowledge systematic studies of the evolution of lubricant film thickness in EHD contacts subjected to forced harmonic variation of load are even less common. The aim of the present study is to explore the effect of load amplitude on the EHD film behaviour. This is done in alternating cycles with the load varying about a fixed, preset value at various amplitudes. Experimental results are compared with a simple theoretical analysis based on the speed of change of contact’s dimensions, a semi-analytical solution which includes both speed variation and squeeze effect, and finally with a full numerical solution.

中文翻译：

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周期性载荷变化下工作参数对弹性流体动力膜厚度的影响

有许多广泛使用的机械部件，例如滚动元件轴承，齿轮和凸轮，它们在称为弹性流体力学（EHD）的润滑方式下工作，其中润滑剂膜的厚度由会聚几何形状的流体力学作用，非弹性流体之间的弹性变形控制。 -保形的接触表面，以及润滑剂粘度随压力的增加。可变的负载条件不仅发生在上述所有机器组件中，而且还发生在自然关节中，例如人类的髋关节或膝关节或许多脊椎动物。关于EHD膜在可变载荷下的行为的实验研究很少，并且据作者所知，对EHD触点在载荷的强制谐波变化下的润滑膜厚度演变的系统研究还很少见。本研究的目的是探讨负荷振幅对EHD胶卷性能的影响。这是在交替的周期中完成的，负载在各种振幅下都围绕固定的预设值变化。将实验结果与基于接触尺寸变化速度的简单理论分析，包括速度变化和挤压效应的半解析解进行比较，最后给出完整的数值解。