力学与实践 ›› 2022, Vol. 44 ›› Issue (4): 918-924.DOI: 10.6052/1000-0879-22-022

• 教育研究 • 上一篇    下一篇

碰撞——理论力学的盲区

余同希()   

  1. 香港科技大学,中国香港
  • 收稿日期:2022-01-10 出版日期:2022-08-08 发布日期:2022-08-17
  • 作者简介:E-mail: metxyu@ust.hk

COLLISION: A BLIND SPOT IN “PARTICLE AND RIGID-BODY DYNAMICS”

YU Tongxi()   

  1. The Hong Kong University of Science and Technology, Hong Kong, China
  • Received:2022-01-10 Online:2022-08-08 Published:2022-08-17

摘要:

碰撞是在自然、生活、运动和工程中广泛存在的力学现象。在简要回顾研究历史之后,本文概述了物体对心正碰撞的基本力学规律;同时指出理论力学的动力学部分提供的理论工具仅限于动量守恒和动量–冲量定理,对撞击力、撞击脉冲和能量损失这些重要的力学量均不能给出任何信息。接着介绍了在线弹性力学、接触力学和弹塑性力学等不同框架下对碰撞问题建立的力学模型,强调碰撞之后的恢复系数并不是材料常数,它同撞击速度密切相关。文章最后呼吁在力学基础教学改革中要弥补碰撞力学知识,帮助学生树立正确的概念。

关键词: 碰撞, 动量定理, 撞击脉冲, 能量损失, 恢复系数

Abstract:

Collision is a kind of mechanical phenomena which widely exist in nature, people’s live, sports and engineering. After a brief review of historical development, the article summarizes the fundamental laws of collinear collision between two particles/bodies, and points out that the particle dynamics only provides us the law of momentum conservation and the momentum-impulse theorem, with no information on the magnitude and pulse shape of colliding force, or on energy loss during collision. The mechanical models of collision based on linear elasticity, contact mechanics and elastoplastic theory are respectively illustrated, indicating that the coefficient of restitution (COR) is not a material constant. Finally, the article calls for making up the knowledge of collision dynamics in the teaching reform of basic mechanics, so as to help students to establish correct concepts.

Key words: collision, theory of momentum, colliding pulse, energy loss, coefficient of restitution

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