组合变形D.PPT

§9–1 SUMMARY §9–1 概 述 ②每个外力分量对应 的内力方程和内力图 ③叠加弯矩，并画图 ④确定危险面 (Nm) Mz x My (Nm) x Mn (Nm) x M (Nm) Mmax x 32 ⑤Plot the diagram of stress distribution in the critical section and determine the critical point. ⑥Establish the strength condition 33 x B1 B2 My Mz Mn M x M ⑤画危险面应力分布图，找危险点 ⑥建立强度条件 34 x B1 B2 My Mz Mn M x M 35 36 35 ①Analysis of external forces：Reduce the external forces to the centroid of section and resolve them. ③ Analysis of stresses : Establish strength conditions. Steps of solving the problem of composite deformation of bending and torsion: ② Analysis of internal forces ：Determine the internal equation and its diagram corresponding toeach external force component and critical section. 37 ①外力分析：外力向形心简化并分解。 ②内力分析：每个外力分量对应的内力方程和内力图，确定危 险面。 ③应力分析：建立强度条件。 弯扭组合问题的求解步骤： 38 Example 3 A hollow circular shaft is shown in the figure.Its inside diameter is d=24mm and its outside diameter is The diameters of pulley B and D are respectively D=30mm D1 =400mm and D2 =600mm，P1=600N，[?]=100MPa. Try to check the strength of the shaft with the third strength . ①Analysis of external forces： Bending and torsion 80o P2 z y x P1 150 200 100 A B C D 150 200 100 A B C D P1 Mx z x y P2y P2z Mx Solution: 39 [例3] 图示空心圆轴，内径d=24mm，外径D=30mm，B 轮直径D 1 ＝400mm，D轮直径 D 2＝600mm，P1=600N，[?]=100MPa，试用第三强度理论校核此轴的强度。 ①外力分析： 弯扭组合变形 80o P2 z y x P1 150 200 100 A B C D 150 200 100 A B C D P1 Mx z x y P2y P2z Mx 解： 40 ②Analysis of internal forces：Internal forces in the critical section are： ③Analysis of stress： It is safe (Nm) Mz x My (Nm) x Mn (Nm) x M (Nm) 71.3 x 71.25 40 7.05 120 5.5 40.6 41 ②内力分析：危险面内力为： ③应力分析： 安全 (Nm) Mz x My (Nm) x Mn (Nm) x M (Nm) 71.3 x 71.25 40 7.05 120 5.5 40.6 42 §9–4 BENDING AND TENSION OR COMPRESSION ? ECCENTRIC TENSION OR COMPRESSION ? KERNEL OF THE SECTION P R P x y z P My x y z P My Mz 1、Composite deformation of bending and tension or compression：Deformation of the rod due to simultaneous action of transversal and