理论力学教学案例——外推式平开窗的运动分析

A TEACHING CASE IN THEORETICAL MECHANICS——KINEMATIC ANALYSES OF A PUSH-OUT CASEMENT WINDOW

外推式平开窗的打开和关闭由窗扇上下与窗框连接的连杆机构实现,其窗扇的运动分析是理论力学教学中一个典型的实践案例。本文给出了这一实例的简化模型和问题的描述,利用直角坐标法和基点法,对窗扇边缘点的运动方程、轨迹、速度和加速度进行分析,并从动力学角度讨论了如何开窗最省力。

The opening and closing motions of a push-out casement window are controlled by the linkage between casement and frame.The kinematics of the casement is a typical practical case in the lecture of theoretical mechanics.In this article,a simplified model and a formulation of the problem for this kinematic process are given.Using the cartesian-coordinate method and pole method,the equations of motion,trajectory,velocity,and acceleration of the casement edge are established and analyzed subsequently.In addition,the approach to open the window with the smallest force is discussed.