一、重点:水螅体壁的各种细胞的结构和功能。 二、难点:海产腔肠动物发育的世代交替现象

一、公关调查.r .. Research 二、公关策划P.r .. Planing 三、公关实施P.r .. Communication 四、公关评估P.r.Evaluation 五、四大步骤形成环状结构一“RPCE”循环

Recall the definition of stress: o stress =\intensity of internal force at a point\ Figure 3.1 Representation of cross-section of a general body

Sources of Stresses and Strains Depends on type of structure Aircraft

As we've previously noted, we may often want to describe a structure in various axis systems. This involves... Transformations (Axis, Deflection, Stress, Strain, Elasticity Tensors) e.g., loading axes material principal axis Figure 7.1 Unidirectional Composite with Fibers at an Angle

Summarizing what we've looked at in elasticity, we have: 15 equations in 15 unknowns 3 equilibrium -6 strains -6 strain-displacement -3 displacements

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:

Return to the simplest system the single spring-mass This is a one degree-of-freedom system with the governing equation

Before we look specifically at thin-walled sections, let us consider the general case (i.e, thick-Walled) Hollow thick-walled sections Figure 12.1 Representation of a general thick-walled cross-section 中=c2 on one boundary φ=c1 on one boundary This has more than one boundary(multiply-connected do=0 on each boundary

Earlier looked at Simple Beam Theory in which one considers a beam in the x-z plane with the beam along the x-direction and the load in the z-direction Figure 14.1 Representation of Simple Beam Now look at a more general case Loading can be in any direction