ANALYSIS OF STRESS AND MOHR'S CIRCLE IMPORTANT TERMS AND DEFINITIONS.

ANALYSIS OF STRESS AND MOHR'S CIRCLE

IMPORTANT TERMS AND DEFINITIONS.:-

IMPORTANT TERMS AND DEFINITIONS.:-

1. Body Force :  A force acting distributed over the volume of body is termed as a body forces. 

BODY FORCE = Force/Volume OR Unit mass 

2. Surface Force : A force which acts distributed over the surface area is called a surface force.

 Surface force  =  Force/ Surface Area 

3. Principal plane : The plane on which only normal stresses acts and no shear stress is called as principal plane.

Plane AB, BC, CD and AD as shown in figure carries only normal stress and no shear stress. These planes are called as principal planes.

4.  Principal stress : The magnitude of normal stress acting on the principal plane is called as principal stress.

5. Major principal stress:

• It is maximum value of normal stress acting on the principal plane.
• It is the maximum intensity of direct stress.

6.Minor principal stress :

• It is the minimum value of normal stress acting on the principal plane.
• It the minimum intensity of direct stress.

7. Major principal plane : plane which carries the major principal stress is called as major principal plane

8. Minor principal plane : plane which carries the minor principal stress is called as minor principal plane

9. Resultant stress : The resultant of the normal stress and the tangential stress is called as resultant stress.

 It is denoted by "σ.r"

where ,σ.n  =  Normal stress,
              て  =    Tangential stress

10. Angle of obliquity : The angle made by the resultant stress with the normal stress is called as angle of obliquity. It is denoted by "Φ" .
                 TanΦ = て/σ.n

11. Stresses on a oblique section of a body: Following are various cases, for determination of stresses on an oblique section of body:

1. A member subjected to axial stress.
2. A member subjected to normal stresses in two mutually perpendicular directions.
3. A member subjected to shear stress. 
4. Member subjected to normal stresses in two mutually perpendicular direction accompanied by a simple shear stress.

MOHR'S CIRCLE METHOD OF STRESS ANALYSIS.

A graphical method of finding principal stresses, normal, tangential and RESULTANT stress with the help of circle is called Mohr's circle method .

1. In this method, direct stress 'σ' is represent on x-axis and shear stress 'て' on y-axis .
2. Tensile direct stress is taken on x-axis and compressive direct stress on negative x-axis.
3. Shear stress produced clockwise moment in the element is considered positive and anticlockwise moment is negative.
4.  Centre of circle is found by, 
5. 
6. where o, and o, are direct stresses.
7. Radius of circle, 
8. 
9. In Mohr's circle , the angle between the planes will be represented by double the angle.
10.  For eg. when circle drawn from centre C with radius R, it cuts x-axis at points and B where shear stress is zero. The angle between AOB-180 but angle between two principal planes is 90.
11. At point A and B, since there is no shear stress, OA and OB represents principal stresses.
12. Radius of circle mohr's circle indicates the maximum shear stress, which is located at 2 0 with respect to x-axis, i.e. at 2x45=90 . 

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