Wednesday, September 4, 2013

Rules for drawing Mohr's Circle to find out Principal Stresses

Rules for drawing Mohr's circle for normal and shear stresses:
1. On rectangular S - T (S- normal stress, T - shear stress) axis, plot the points having co-ordinates A(Sx, Tyx) and B ( Sy, Tyx). Assume tension as positive/plus, compression as minus, and shear stress as plus when its moment about center is clockwise.
2. Join these points, with a straight line AB which gives us the diameter of the circle whose center is on S-axis.
3. The radius of the circle to any point on its circumference represents the axis directed normal to the plane whose stress components are given by the co-ordinates of that point.
4. The angle between the radii to selected points on Mohr's circle is twice the angle between the normals to the actual planes represented by these points.

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