一、教学目标和教学内容 1．教学目标 掌握梁纯弯曲时横截面上正应力计算公式的推导过程，理解推导中所作的基本假设

重庆大学：《材料力学》课程教学资源（教案讲义）第十二章 开口薄壁杆件

I Atom movement in sol ids mechanical movement thermal vibration (short-range migration) Thermal motion diffusion(long-range migration)

5. 19 Reaction between Dislocation Condition 1. Geometrical condition

Back stress exerted by obstacle on leading dislocation. (It is supposed to be a short-range-force.) nrbdx =tpbdx dx virtual displacement

5.16 Dislocation in FCC crystals Perfect dislocation b =na, +nb. +nC

5. 8 The Stress Around a Dislocation 1. Screw dislocation: Displacement:

1. There have no two-phases area in diffusion area, every layer is single-phases 2. Phase's interface moves according to parabola law 3. Phase's width

36. 5 concentration dependence of D. Matano method d -C- dependence ll Matano method

1. Classification y Ideal or perfect crystal real or defect crystal According to dimension o point defect: vacancies, interstitial atoms s line defect dislocation planar defect: stacking fault o volume defect mosaic structure