机械设计04_应力分析.pptVIP

04 Stress Purpose Forces inside an Object under Applied Loads Force at an Internal Point Stress at an Internal Point State of Stress: Stress Components 3D Cartesian Stress: Sign Convention 2D Cartesian Stress: Sign Convention 2D Cartesian Stress: Transformation Transformation of 2D Cartesian Stress 2D Cartesian Stress: Principal Stresses 2D Principal Stresses: Procedure Principal Shear Stress Principal Shear Stresses: Procedure Example 1 Example 1: Principal Stresses Example 1: Principal Shear Stresses Example 1: Summary Example 2: Solve Ex. 1, Using Mohr’s Circle Example 2: Constructing Mohr’s Circle Example 2: Principal Stresses Example 2: Principal Shearing Stresses Principal Stress and Principal Shear Stress General State of Stress: 3D Cartesian Stress Tensor 3D Principal Stresses 3D Principal Stresses: Eigenvalue Problem 3D Principal Stresses: Stress Invariant 3D Principal Shear Stress 2D Maximum Shear Stress Esc TOPIC School of Engineering Mechanical Engineering ME 461 Design ? Tulong Zhu, All rights reserved. The stress state at critical locations in a machine component is required to evaluate whether the component will satisfy strength design requirements. The purpose of this class is to review the concepts and equations used to evaluate the state of stress at a point. Traction – Distributed Force per Unit Area P1 P2 P1 P2 DVx DFx DA x x y y z z DFx DVx z DVx y The internal force acting on the area DA has 3 components (1 normal, 2 shears): (Superscript x indicates that DA is perpendicular to x). P2 P3 P4 x y z P1 Consider a member subjected to a general combination of loads P1, P2 , P3, etc. Force Cut the member to reveal the internal force applied on an infinitesimal area DA at point Q. P1 P2 P1 P2 DVx DFx DA x x y y z z DFx DVx z DVx y z y x txy txz sx The internal stress components are defined as, Force txy and txz are the stresses on a surface perpendicular to the x-axis, and point to the y- and z- axes, respecti