Strength of Materials

2.1 STRESS AT A POINT

As discussed in Chapter 1, materials are regarded as continuum and stresses and strains are evaluated considering an infinitesimal element having the same properties of the entire mass. Thus, stress at a point in a material has to be viewed as a large point with representative materials of the whole mass.

In such a system tensile stress is considered as positive, compressive stress as negative and shear stress causing a clockwise torque about the centre of a free body as positive.

An incremental element is considered with the stresses acting on the planes to represent the stress conditions at a point in a material as shown in Figure 2.1.

 

 

Fig. 2.1 Stresses acting as an element.

 

Here, p_x, p_y and p_z are the normal ...