理论力学双语教学第一章静力学基本公理和物体的受力分析.ppt

1 P N N P NA NB Common normal Common tangent Pin Smooth cylindrical pin 3.光滑圆柱铰链约束 ①圆柱铰链 ① cylindrical pin A XA YA A A Direction is uncertain Magnified picture Pin ②fixed hinged support ②固定铰支座 fixed hinged support 固定铰支座 runner and pin (double surface constraints) 滑槽与销钉 （双面约束） runner and pin (double surface constraints) 滑槽与销钉 （双面约束） double force equivalent rod 二 力 杆 double force equivalent rod 二 力 杆 Kinetic hinged support (step bearing) 活动铰支座（辊轴支座） N的实际方向也可以向下 The actual direction of N can be downward. Kinetic hinged support (step bearing) 活动铰支座（辊轴支座） §1-4 Force analysis and force diagrams §1-4 物体的受力分析和受力图 1. Force analysis To solve a problem of static. First select the body to be studied. 一、受力分析 解决力学问题时，首先要选定需要进行研究的物体，即选择研究对象； Secondly, in accordance with the given conditions and constraints, analyze the forces which act on the bodies using the basic concepts and principles. This process is called force analysis. 然后根据已知条件，约束类型并结合基本概念和公理分析它的受力情况，这个过程称为物体的受力分析。 The forces acting on a body can be classified as: 作用在物体上的力有： 1: active forces, such as the gravitational force, the force of wind power, the pressure of gases, etc. 一类是:主动力,如重力,风力,气体压力等。 2: passive forces, such as reaction force of constraints 二类是：被动力，即约束反力。 The main steps to draw the force diagrams: 画物体受力图主要步骤为： ①select the object under study; ①选研究对象； ②divide the object into several parts and study the parts one by one; ②取分离体； ③draw the active forces; ③画上主动力； ④draw the reaction force of the constraints. ④画出约束反力。 2. Force diagrams 二、受力图 [Example 1] [例1] Q A O B C D E [Example 2] Please, draw the force diagrams for all components in the picture. [例2] 画出下列各构件的受力图 Rod Q A O B C D E Q A O B C D E Q A O B C D E Q A O B C D E [Example 3] Please, draw the force diagrams for all components in the picture. [例3] 画出下列各构