[理学]工程力学-第4章ppt课件

1、TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY前往总目录前往总目录TSINGHUA UNIVERSITY前往前往前往总目录前往总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA U

2、NIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY前往前往前往总目录前往总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY分布力：延续作用于构件外表的力。集中力：作用面积极小的分布力

3、。面力按载荷随时间变化情况1.静载荷 2.动载荷TSINGHUA UNIVERSITYTSINGHUA UNIVERSITY梁拉杆TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY截面法用假设平面将构件截开从而提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：保管研讨部分，弃去其它部分。代：以截面上的内力替代被弃部分对保管部分的作用。平：建立保管部分的平衡方程，确定未知内力。TSINGHUA UNIVERSITYF1F3F2FnBAF1F2F3FnABTSINGHUA UNIVERSITYF1FRF3MF1F

4、3TSINGHUA UNIVERSITYFRFNFQMMBMxTSINGHUA UNIVERSITY 在一定条件下，杆件一切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 yFNMzTSINGHUA UNIVERSITYFAyFByTSINGHUA UNIVERSITYFAyFByTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY前往前往

5、前往总目录前往总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYF1F3F2FnF1F2F3FnTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYFN=FFFFFFFFTSINGHUA UNIVERSITYM M0M0M0M0M0M0M0M0TSINGHUA UNIVERSITY前往前往前往总目录前往总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYyx

6、zAFAlimN0 AFAlimQ0 AFQyFQzFNDFRFP1FP2TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYFP1FP2yxzdAxMyFN xxAxFANdyAxMzAdzAxMyAdTSINGHUA UNIVERSITYFP1FP2yxzdAxyxzyAxyFAQdAxyzAdzAxzFAQdxAxzMyAdTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY前往前往前往总目录前往总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIV

7、ERSITYxu+duxxxuxdddxxu 单元体的两条相互垂直的棱边，在变形后的直角改动量。长度在变形前后的改动量与原长之比。TSINGHUA UNIVERSITYTSINGHUA UNIVERSITY前往前往前往总目录前往总目录TSINGHUA UNIVERSITYEExxxx,GG,OxxOTSINGHUA UNIVERSITY前往前往前往总目录前往总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITY前往前往前往总目录前往总目录TSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGHUA UNIVERSITYTSINGH