The mohr’s circle is a method of analyzing stress ( tensile, shear) at a given body usingÂ geometrical figures andÂ methods. This Â involve some simple and basic calculations of geomatry that’s why Mohr’s circle give a flexible approch to solve a mechanic problem related to analyzing for stresses and strains.

Mohrâ€™s Circle Sing Convention.

1) Tensile stress will be positive if it tends to elongate the body you can see bothÂ ?x andÂ ?y are positive in the figure.

2) Â Â Shear stresses tending to rotate the element clockwise (cw) are plotted above the

? axis.

â€¢ Shear stresses tending to rotate the element counterclockwise (ccw) are plotted below

the ? axis.

in some books this convention is taken as

Â Shear stress ( applied perpendicular toÂ ?x Â at the right side of the body )Â will be positive if it tends to rotate the body in counter clock wise.Â

ConstructionÂ

1)Â create a coordinate system with normal stresses plotted along theÂ abscissa and shear stresses plotted as the ordinates.

Â 2) Â On the abscissa, tensile (positive)Â normal stresses are plotted to the right of the origin O and Â ompressive (negative) normalÂ stresses to the left. On the ordinate, clockwise (cw) shear stresses are plotted up;Â counterclockwise (ccw) shear stresses are plotted down.

3)Â If ?x is positive and the shear stress ?xy is ccw as shown in Fig.1 , we canÂ establish point A with Â coordinates

**(?x , ?-xy ccw )**in Fig 24) For Â

**?y**Â repeat the process to obtain point B withÂ coordinates**(?y , ?-xy cw )**5) The line that join point A with point B is the diameter of the circle.