COMBINED DEFORMATIONS 2 Methods to study composite deformation s-Principle of superposition (Analysis of external forces: External forces are reduced along the centroid of section and resolved along principal axes of inertia 2Analysis of internal forces: Determine the internal-force equation and its diagram corresponding to each external force component and the critical section Analysis of stresses: Plot the distribution diagram of the stress in the critical section, do the superposition of the stresses and establish the strength condition of the critical point
2、Methods to study composite deformation s—Principle of superposition ①Analysis of external forces：External forces are reduced along the centroid of section and resolved along principal axes of inertia. ②Analysis of internal forces：Determine the internal-force equation and its diagram corresponding to each external force component and the critical section. ③Analysis of stresses：Plot the distribution diagram of the stress in the critical section，do the superposition of the stresses and establish the strength condition of the critical point. 11
组合变彩 二、组合变形的研究方法叠加原理 ①外力分析:外力向形心(或弯心)简化并沿形心主惯性轴分解 ②内力分析:求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:画危险面应力分布图,叠加,建立危险点的强 度条件。 12
二、组合变形的研究方法 —— 叠加原理 ①外力分析：外力向形心(或弯心)简化并沿形心主惯性轴分解 ②内力分析：求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：画危险面应力分布图，叠加，建立危险点的强 度条件。 12
COMBINED DEFORMATIONS S9-2 SKEW BENDING 1 Skew bending: After bending deformation, the deflection curve and the external forces transversal forces) of the rod are not in the same plane 2 Methods to study the skew bending 1).Resolve: Resolve the external load along two centroid principal axes of inertia of the cross section and get two perpendicular planar bending P P J y 13
§9–2 SKEW BENDING 1、Skew bending：After bending deformation , the deflection curve and the external forces（transversal forces） of the rod are not in the same plane 2、Methods to study the skew bending： 1).Resolve：Resolve the external load along two centroid principal axes of inertia of the cross section and get two perpendicular planar bending . Pz Py y z P j x y z P Py Pz 13
组合变影 §9-2斜弯曲 斜弯曲:杆件产生弯曲变形,但弯曲后,挠曲线与外力(横 向力)不共面。 二、斜弯曲的研究方法: 1.分解:将外载沿横截面的两个形心主轴分解,于是得到两个正交 的平面弯曲。 P P y y 1
§9–2 斜弯曲 一、斜弯曲：杆件产生弯曲变形，但弯曲后，挠曲线与外力（横 向力）不共面。 二、斜弯曲的研究方法 ： 1.分解：将外载沿横截面的两个形心主轴分解，于是得到两个正交 的平面弯曲。 Py Pz Pz Py y z P j 14 x y z P Py Pz 13
COMBINED DEFORMATIONS 2). Sum: analyze bending in two perpendicular planes and sum the results of the calculation P J P P y 15
2).Sum：Analyze bending in two perpendicular planes and sum the results of the calculation. x y z Py Pz P Pz Py y z P j 15