2016工程力学-材料力学（高教版）教案：第四章 弯曲内力.docVIP

第四章 弯曲内力 1Mechanics of Materials23§ 4–1 Concepts of planar bending and calculation sketch of the beam§ 4–2 The shearing force and bending moment of the beam§ 4–3 The shearing-force and bending-moment equations · the shearing-force and bending-moment diagrams?4? Relations among the shearing force,the bending moment and thedensity of the distributed load and their applications?4? Plot the bending-moment diagram by the theorem ofsuperpositiom?4? The internal-force diagrams of the planar rigid theorem framesand curved rodsExercise lessons about the internal force of bendingCHAPTER 4 INTERNAL FORCES IN BENDING4§ 4–1 平面弯曲的概念及梁的计算简图§ 4–2 梁的剪力和弯矩§ 4–3 剪力方程和弯矩方程 ·剪力图和弯矩图§ 4–4 剪力、弯矩与分布荷载集度间的关系及应用§ 4–5 按叠加原理作弯矩图§ 4–6 平面刚架和曲杆的内力图弯曲内力习题课第四章 弯曲内力5§ 4–1 CONCEPTS OF PLANAR BENDING ANDCALCULATION SKETCH OF THE BEAM1,CONCEPTS OF BENDING1),BENDING,The action of the external force or external the couple vectorperpendicular to the axis of the rod makes the axis of the rod change intocurve from original straight lines,this deformation is called bending,2).BEAM,The member ofwhich the deformation ismainly bending is generallycalled beam,6§ 4–1 平面弯曲的概念及梁的计算简图一、弯曲的概念1,弯曲, 杆受垂直于轴线的外力或外力偶矩矢的作用时,轴线变成了曲线，这种变形称为弯曲。2,梁,以 弯曲变形为主的构件通常称为梁。73).Practical examples in engineering about bending83,工程实例910114).Planar bending,After deformation the curved axis of thebeam is still in the same plane with the external forces,Symmetric bending（ as shown in the following figure） — aspecial example of the planar bending,The plane ofsymmetry MP1 P2 q124,平面弯曲,杆发生弯曲变形后，轴线仍然和外力在同一平面内 。对称弯曲（如下图） —— 平面弯曲的特例。纵向对称面 MP1 P2 q13Unsymmetrical bending— if a beam does not possess any plane ofsymmetry,or the external forces do not act in a plane of symmetry of thebeam with symmetric planes,this kind of bending is called unsymmetricalbending,In later chapters we will mainly discuss the bending stresses anddeformations of the beam under symmetric bending,14