ch2-轴向拉压-wsb.pptVIP

2.9 Saint-Venant’s Principle 2.7 Saint-Venant’s Principle Sample Problem SOLUTION: B Sample Problem SOLUTION: C Sample Problem SOLUTION: u=? v= ? Sample Problem SOLUTION: C v Sample Problem SOLUTION: Bars AB and AC each have a cross sectional area A = 60 mm2 and a modulus of elasticity E = 200 GPa The dimensions h = 200 mm If a downward force F = 40 kN is applied at A what is the resulting horizontal and vertical displacements of point A? text, p. 104 Stress Strain: Axial Loading Ch.2 Axial Forces text, p. 104 Stress Strain: Axial Loading Ch.2 Axial Forces Axial Forces Mechanics of Materials 材料力学 Professor Shibin WANG （王世斌） N N N 2.1 Bars Under Simple Tension – Elastic Behaviour Ch.2 Axial Forces 2.1 Bars Under Simple Tension – Elastic Behaviour Ch.2 Axial Forces ? N（kip) 4 ? 8 x N=P 2.2 Simple Stress Calculations: square section bar P P b 2b P Left section: ?? =P (equilibrium) Right section: P x UNITS? N Ch.2 Axial Forces Ch.2 Axial Forces 2.3 Stress Distribution Ch.2 Axial Forces 2.4 Design Consideration ?Ultimate Strength of a Material ? Allowable Load and Allowable stress; Factor of Safety 强度条件 ? No.8 No.10 30o A C B 三角架：Q235； AB： 两根等边角钢80? 80 ? 7 AC： 两根10号槽钢 [?] =120MPa , 求许可载荷 P Ch.2 Axial Forces 2.5 Sample Problem 1 解：1. 受力分析 30? P x N2 N1 A y …(1) …(2) No.8 No.10 30o A C B Ch.2 Axial Forces 2.5 Sample Problem 1 30? P x N2 N1 A y 2. 计算许可轴力[N] 2.6 Deformation and Strain ( 变形和应变 ) ? Elastic Stiffness (Robert Hooke, 1648) Elastic deformation of materials will be the focus of this course. Plenty of challenging problems in this area… ? Hooke’s Law (Young Poisson) ? Material Properties (Thomas Young, 1810) ? Temperature Strains (William Rankine, 1870) ? Mat. Props (Cont.) (Simon Poisson, 1825) ? Strain Energy (Carlo Castigliano, 1881) As in all areas of science, a variety of people have made significant contributions to the Mechanics of Materials. The A-list: Ch.2 Axial Forces Robert Hooke was the first to experiment with and define the