We do not characterize materials by their E mnpq The Emnpa are useful in doing transformations, manipulations, etc. We characterize materials by their \ENGINEERING CONSTANTS\ (or, Elastic Constants)

Sources of Stresses and Strains Depends on type of structure Aircraft

延安大学：《结构力学 Structural Mechanics》课程教学资源（电子教案，打印版）

Let's first review a bit... from Unified, saw that there are basic considerations in elasticity: 1. Equilibrium 2. Strain-Displacement 3. Stress- Strain Relations (Constitutive Relations)

1、几何组成特性 2、静力特性 静定结构的内力计算依据静力平衡原理

The logical extension of discrete mass systems is one of an infinite number of masses. In the limit, this is a continuous system. Take the generalized beam-column as a generic representation:

Previously saw (in Unit 19)that a multi degree-of-freedom system has the same basic form of the governing equation as a single degree-of-freedom system The difference is that it is a matrix equation

For a number of cross-sections we cannot find stress functions. However, we can resort to an analogy introduced by Prandtl(1903) Consider a membrane under pressure p, Membrane\. structure whose thickness is small compared to surface

§10.1 概述 §10.2 单元刚度矩阵（局部坐标系) §10.3 单元刚度矩阵（整体坐标)

第一节 力矩分配法概念 第二节 多结点的力矩分配法