工程力学-第4章

1、TSINGHUA UNIVERSITYTSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY 返回总目录返回总目录TSINGHUA UNIVERSITY返回返回 返回总目录返回总目录TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSI

2、TY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY返回返回 返回总目录返回总目录TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY 分布力

3、：连续作用于构件表面的力。集中力：作用面积极小的分布力。面力按载荷随时间变化情况1.静载荷 2.动载荷TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY 梁拉杆TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY 截面法用假设平面将构件截开从而揭示构件内力并确定内力的方法。截：用假设平面将构件在欲求内力处截开。弃：保留研究部分，弃去其它部分。代：以截面上的内力代替被弃部分对保留部分的作用。平：建立保留部分的平衡方程，确定未知内力。TSINGHUA UNIVERSITY F1F3F2FnBAF1F2F3

4、FnABTSINGHUA UNIVERSITYF1FRF3MF1F3 TSINGHUA UNIVERSITYFRFNFQMMBMx TSINGHUA UNIVERSITY 在一定条件下，杆件所有内力分量作用的效果，可以视为各个内力分量单独作用效果的叠加。通常可归结为三组平面内内力分量与外力：yxzFP1 FP2FRMMzMyMxFQ yFQ zFNFQ TSINGHUA UNIVERSITYyxzMxyxzFQ zFNMyyxzFQ yFNMz TSINGHUA UNIVERSITY FAyFByTSINGHUA UNIVERSITY FAyFByTSINGHUA UNIVERSITY TSI

5、NGHUA UNIVERSITY TSINGHUA UNIVERSITY返回返回 返回总目录返回总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYF1F3F2FnF1F2F3FnTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYFN=FFFFFFFFTSINGHUA UNIVERSITYM M0M0M0M0M0M0M0M0TSINGHUA UNIVERSITY返回返回 返回总目录返回总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSIT

6、Y 内力的集度或单位面积上内力的大小。TSINGHUA UNIVERSITY TSINGHUA UNIVERSITYyxzAFAlimN0 AFAlimQ0 AFQyFQzFNDFRFP1FP2TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYFP1FP2yxzdAxMyFN xMzxAxFANdyAxMzAdzAxMyAdTSINGHUA UNIVERSITYFP1FP2yxzdAxyxzyAxyFAQdAxyzAdzAxzFAQdxAxzMyAdTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY返回返

7、回 返回总目录返回总目录TSINGHUA UNIVERSITY TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYxu+duxxxuxdddxxu 单元体的两条相互垂直的棱边，在变形后的直角改变量。长度在变形前后的改变量与原长之比。TSINGHUA UNIVERSITYTSINGHUA UNIVERSITY返回返回 返回总目录返回总目录TSINGHUA UNIVERSITYEExxxx,GG,OxxO TSINGHUA UNIVERSITY返回返回 返回总目录返回总目录TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA U

8、NIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY TSINGHUA UNIVERSITY返回返回 返回总目录返回总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTS