理论力学：《运动学》课程PPT教学课件（双语）第九章 刚体的平面运动

Theoretical mechanics Chapter o plane motion of a rigid body

1 Theoretical mechanics

理论力学

2

Chapter 9: Plane motion of a rigid body 89-1 Introduction to plane motion of a rigid body 89-2 Plane motion can be decomposed into translation and rotation Equations of plane motion 四§9-3 Velocity of a point in a plane figure 回§9-4 Acceleration of a point in a plane figure Instantaneous center of zero acceleration Lesson for problem solving

3 §9–1 Introduction to plane motion of a rigid body §9–2 Plane motion can be decomposed into translation and rotation · Equations of plane motion §9–3 Velocity of a point in a plane figure §9–4 Acceleration of a point in a plane figure · Instantaneous center of zero acceleration Lesson for problem solving Chapter 9: Plane motion of a rigid body

第九章刚体的平面运动 回§9-1刚体平面运动的概述 §9-2平面运动分解为平动和转动 刚体的平面运动方程 §9-3平面图形内各点的速度 §9-4平面图形内各点的加速度 加速度瞬心的概念 习题课

4 §9–1 刚体平面运动的概述 §9–2 平面运动分解为平动和转动 · 刚体的平面运动方程 §9–3 平面图形内各点的速度 §9–4 平面图形内各点的加速度 · 加速度瞬心的概念 习题课 第九章 刚体的平面运动

Kinematics 89-1 Introduction to plane motion of a rigid body In engineering, we often encounter the plane motion of a rigid body which is more complicated. Investigation into this kind of motion is conducted on the basis of translation and rotation of a rigid body using composition and decomposition of motions. Decomposing a plane motion into translation and rotation, and employing the theory of composition of motions the formulae for finding the velocity and acceleration of point in the rigid body can be derived 1. Definition of plane motion of a rigid body The distance between any point in a rigid body and a fixed plane al ways keeps unchanged during its motion. In other words, any point in the rigid body moves in a plane parallel to the fixed plane The motion described above is called plane motion of a rigid body

5 In engineering, we often encounter the plane motion of a rigid body, which is more complicated．Investigation into this kind of motion is conducted on the basis of translation and rotation of a rigid body using composition and decomposition of motions.Decomposing a plane motion into translation and rotation, and employing the theory of composition of motions，the formulae for finding the velocity and acceleration of point in the rigid body can be derived. §9-1 Introduction to plane motion of a rigid body 1. Definition of plane motion of a rigid body The distance between any point in a rigid body and a fixed plane always keeps unchanged during its motion. In other words, any point in the rigid body moves in a plane parallel to the fixed plane. The motion described above is called plane motion of a rigid body

远动学 s9-1刚体平面运动的概述 刚体的平面运动是工程上常见的一种运动,这是一种较为 复杂的运动.对它的研究可以在研究刚体的平动和定轴转动的 基础上,通过运动合成和分解的方法,将平面运动分解为上述 两种基本运动.然后应用合成运动的理论,推导出平面运动刚 体上一点的速度和加速度的计算公式 一,平面运动的定义 在运动过程中,刚体上任一点到某一固定平面的距离始终保 持不变.也就是说,刚体上任一点都在与该固定平面平行的某一 平面内运动.具有这种特点的运动称为刚体的平面运动

6 刚体的平面运动是工程上常见的一种运动，这是一种较为 复杂的运动．对它的研究可以在研究刚体的平动和定轴转动的 基础上，通过运动合成和分解的方法，将平面运动分解为上述 两种基本运动．然后应用合成运动的理论，推导出平面运动刚 体上一点的速度和加速度的计算公式． §9-1 刚体平面运动的概述 一．平面运动的定义 在运动过程中，刚体上任一点到某一固定平面的距离始终保 持不变．也就是说，刚体上任一点都在与该固定平面平行的某一 平面内运动．具有这种特点的运动称为刚体的平面运动．

Kinematics B For example: Examine the motion of the rod in a crank-rod mechanism. Since point A moves in a circular path, and pint B move along a straight line, the motion of the rod ab is neither translation nor rotation about a fixed axis but plane motion 7

7 For example : Examine the motion of the rod in a crank-rod mechanism. Since point A moves in a circular path , and pint B move along a straight line，the motion of the rod AB is neither translation nor rotation about a fixed axis，but plane motion

远动学 例如:曲柄连杆机构中连杆AB的运动, A点作圆周运动,B点作直线运动,因此, AB杆的运动既不是平动也不是定轴转动, 而是平面运动

8 例如: 曲柄连杆机构中连杆AB的运动， A点作圆周运动，B点作直线运动，因此， AB 杆的运动既不是平动也不是定轴转动， 而是平面运动．

Kinematics B B 0 A 01.A Please ook at the animation

Please look at the animation 9

远动学 B B 0 A 01.A 请看动画 10

请看动画 10