Name: friction moment in journal bearings
Uploaded: 2023-09-22T11:49:30.000Z
Duration: 1 min 23 s
Channel: JoVE

滑动轴承用于为旋转轴和车轴提供横向稳定性。
考虑一个具有干燥或部分润滑滑动轴承的绳索绞车。
卷轴顺时针旋转导致轴缠绕轴承内表面，直至发生滑动并进入稳定旋转状态。
绘制出该轴的受力分析图。作用在系统上的力包括轴的重力、顺时针力偶以及轴承的反作用力。
非共线反作用力与重力大小相等、方向相反，并相对于表面法线成一定角度作用。该角度称为动摩擦角。
反作用力的作用线始终与摩擦圆相切。
对点 O 的力矩平衡条件可得到轴的力矩。
当动摩擦角较小时，正弦项可近似为动摩擦角的正切值。
由于动摩擦角的正切等于动摩擦系数，因此可得到克服轴承摩擦阻力所需的力矩。

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	<li>梅里亚姆，JL;Kraige， LG 和 Bolton， JN （2020）。工程力学 \u2012 静力学。新泽西州霍博肯:约翰·威利。第 364 页。</li>
	<li>比尔，F.P.;约翰斯顿，ER;马祖克，DF;克伦威尔，PJ 和塞尔夫，BP（2019 年）。工程师的矢量力学 \u2012 静力学和动力学。纽约:麦格劳-希尔。第 459-460 页。</li>
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轴承

Journal Bearings

轴承是位于机械中的零件，用于支撑和提供旋转轴和轴承的横向稳定性。它们能够减少在机械设备（如发动机、涡轮机和泵）中所产生的摩擦、磨损和振动。轴承背后的原理是在轴承表面和旋转轴之间形成一个薄薄的润滑膜，并最大程度地来减少直接接触和摩擦力。 为了更好地理解轴承的概念，假设有一个带有干燥或部分润滑的轴承来支撑其旋转轴的绳索绞盘。当卷筒进行顺时针旋转时，轴便会向上滚动轴，直到它发生打滑并进行稳定的旋转。 <img alt="Figure 1" src="/files/ftp_upload/14326/14326_Figure_1v2.svg" style="text-align: center; height: 300px;"> 可以绘制轴的受力分析图以分析作用在系统上的力。这些力包括了轴的重量，垂直向下作用的力，顺时针力矩，并代表了施加在轴上的力矩，以及轴承对轴所施加的反作用力。非共线反作用力与轴之间的重量相等且方向相反，并以相对于其表面法线方向的角度来产生作用。这个角度被称为动摩擦角。反作用力的作用线始终与产生摩擦的圆相切，代表了轴和轴承之间所有接触点的轨迹。通过将力矩的平衡条件应用到点O（轴的中心），我们可以确定维持其稳定旋转所需的轴矩。 <img alt="Equation 1" src="/files/ftp_upload/14326/14326_Equation_1v2.svg" style="text-align: center; height: 13px;"> 对于较小的动摩擦角，方程中的正弦可以近似的等于动摩擦角的正切。 <img alt="Equation 2" src="/files/ftp_upload/14326/14326_Equation_2v2.svg" style="text-align: center; height: 13px;"> 由于动摩擦角的正切值等于动摩擦系数，我们可以计算克服轴承摩擦阻力所需的力矩。这个力矩是能够确定其系统效率和性能的重要因素。 <img alt="Equation 3" src="/files/ftp_upload/14326/14326_Equation_3v2.svg" style="text-align: center; height: 13px;">

滑动轴承是用于支撑旋转轴和轮轴并提供侧向稳定性的机械部件。它们在减少摩擦方面起着关键作用，……

Education

教育

JoVE Core

Mechanical Engineering

机械工程

Unit 1

第一单元

Friction

摩擦

KEY TERMS AND CONCEPTS

关键术语与概念

friction moment in journal bearings

Journal bearings support rotating shafts and axles while helping keep them stable. They are used in machines such as engines, turbines, and pumps. Their job is to reduce friction, wear, and vibration.

A journal bearing works by keeping a thin film of lubricant between the bearing surface and the rotating shaft. This film limits direct contact and lowers frictional force. The video uses a rope winch with dry or only partly lubricated journal bearings to show the idea.

As the spool turns clockwise, the shaft first rolls up the inner surface of the bearing. It then slips and settles into stable rotation. A free-body diagram of the shaft helps show the forces in the system.

The diagram includes the weight of the shaft, a clockwise couple that represents the applied torque, and the reaction force from the bearing. The reaction force is not collinear with the weight of the shaft. It acts at an angle to the surface normal, and that angle is called the angle of kinetic friction.

The line of action of the reaction force is tangent to the circle of friction. The circle of friction is the set of possible contact points between the shaft and the bearing. By using moment equilibrium about point O, the center of the shaft, the needed shaft moment can be found.

For a small kinetic friction angle, the sine term in the equation can be approximated by the tangent of that angle. Since the tangent of the kinetic friction angle equals the coefficient of kinetic friction, the required moment can be calculated from it. This moment helps describe the bearing’s frictional resistance and its effect on efficiency and performance.

Friction Moment in Journal Bearings

dry friction

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static friction

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kinetic friction

Sliding Friction Between Moving Surfaces

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characteristics of dry friction

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types of friction problems

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friction: problem solving

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frictional forces on screws

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upward impending motion

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self-locking screw

Screw Jack Self-Locking Behavior

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screw: problem solving

Screw Torque and Self-Locking

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frictional forces on flat belts

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flat belts: problem solving

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pivot bearings

Axial Load Support in Pivot Bearings

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collar bearings

Friction Torque in Collar Bearings

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journal bearings

Journal bearings support rotating shafts and axles while helping keep them stable. They are used in machines such as engines, turbines, and pumps. Their job is to reduce friction, wear, and vibration. A journal bearing works by keeping a thin film of lubricant between the bearing surface and the rotating shaft. This film limits direct contact and lowers frictional force. The video uses a rope winch with dry or only partly lubricated journal bearings to show the idea. As the spool turns...

bearings: problem solving

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rolling resistance

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rolling resistance: problem solving

Lawn Roller Force Calculation

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key terms and concepts

Learn how journal bearings support rotating shafts, reduce friction, and create the reaction force and moment used to analyze stable rotation.

Friction Moment in Journal Bearings | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

Friction Moment in Journal Bearings

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