Chapter 9 Buckling of Columns Buckling of Columns
Chapter 9 Buckling of Columns
(Buckling of Columns) 第九章 压杆稳定 (Buckling of Columns ) § 9 -1 压杆稳定的概念 (The basic concepts of columns) § 9 -2 两端铰支细长压杆的临界压力 (The Critical Load for a straight, uniform, axially loaded, pin-ended columns) § 9 -3 其它支座条件下细长压杆的临界压力 (Euler’s Formula for other end conditions )
(Buckling of Columns) § 9 -4 欧拉公式的应用范围 经验公式 (Applicable range for Euler’s formula the experimental formula ) § 9 -5 压杆的稳定校核 (Check the stability of columns) § 9 -6 提高压杆稳定性的措施 (The measures to enhance the columns stability)
(Buckling of Columns) 二、 程实例(Example problem)
(Buckling of Columns)
(Buckling of Columns)
(Buckling of Columns) 四、压杆稳定的基本概念 (The basic concepts of columns) 1. 平衡的稳定性(Stability of equilibrium ) 随遇平衡
(Buckling of Columns) § 9 -2 两端绞支细长压杆的临界压力 (The Critical Load for a straight, uniform, axially loaded, pin-ended columns) x F F M(x)=-Fw l m m w y B m x y x B m
(Buckling of Columns) § 9 -3 其它支座条件下细长压杆的临界压力 (Euler’s Formula for other end conditions ) 1. 细长压杆的形式(Different end conditions of a straight columns) 两 端 铰 支 一端 自由 一端 固定 两 端 固 定 一端 固定 一端 铰支
(Buckling of Columns) 2. 其它支座条件下的欧拉公式(Euler’s Formula for Other End Conditions) Fcr Fcr l l l/4 2 l Fcr 0. 7 l l/2 l l l/4 —相当长度 欧拉公式 —长度因数 0. 3 l l
(Buckling of Columns) 四、压杆的分类及临界应力总图(Classification of Columns and the Diagram of critical stress cr versus slenderness ratio ) 1. 压杆的分类(Classification of Columns ) (1)大柔度杆(Long columns) (2)中柔度杆(Intermediate columns ) (3)小柔度杆(Short columns)
(Buckling of Columns) 2. 临界应力总图 2 1
(Buckling of Columns) 解: 杆A 杆B 杆C A杆先失稳. 1. 3 a a A B F 1. 6 a F F C d
(Buckling of Columns) (2)当 l = 3/4 lmin 时,Fcr=? 用直线公式计算
(Buckling of Columns) 0. 6 解:取 BC 研究 0. 3 B C FN F A 0. 8
(Buckling of Columns) 不能用欧拉公式 0. 6 0. 3 B C F 用直线公式 [F] =118 k. N A 0. 8
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