Stress

Stress: The resistance or force per unit area of deformation is called stress.

 Mathematically,

             

Therefore units of stress is Nm^-2 or Pa in S.I

There are three types of stress:

1.  Tensile stress
2. Compressive stress.      
3. Shear stress

1)  Tensile stress: The stress to which a bar or structure is subjected when intention is called tensile stress.

                                                                                

 2)  Compressive stress: The stress which is subjected when in compression is called compressive stress.

 

3)   Shear stress:  Consider a block of materials (fig-a) subjected to a same of equal and opposite forces Q. There is then a tendency for one layers of the material to slide one another to opposite the form of failure (fig-b).  Therefore, if this failure is restricted then a shear stress is setup as follows-

                       

This shear stress will always be tangential to the area on which it acts direct stress however are always normal to the area which they act.

 

     

                          

                                                       

     #Credit:Prof. Dr. Md. Iqbal Mahmud     
         Dept.of Textile Engineering, MBSTU