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Date : 2016-06-23 12:24:21

DRAWING RULES OF MOHR'S CIRCLE:

  • Fix the origin (0,0) that is (x,y) at convenient place in the graph.
  •  X – axis to locate axial stress for both x and y directions.
  •  Y – axis to locate shear stress for clockwise and anti clockwise shear.
  •  Tensile stress is positive along x axis right of origin.
  • Compressive stress is negative along x axis left of origin.
  • Clockwise Shear stress is positive along y axis upward of origin.
  •  Anti clockwise shear stress is negative along y axis downward of origin..
  • When there is no shear force draw Mohr‟s circle from axial stresses. The centre of the Mohr‟s circle bisects axial stresses.
  • When there is shear force draw Mohr‟s circle from axial stresses and shear stress. The centre of the Mohr‟s circle bisects the line between
  • Angle of inclination is to be drawn from point at centre of Mohr‟s to angle 2θ in clockwise direction.
  • Normal stress, and maximum and minimum principal stresses are taken from the origin along the x-axis of the Mohr‟s circle.
  • Maximum shear stress is the radius of the Mohr‟s circle, and shear stresses are taken along the y-axis of the Mohr‟s circle.
  • The angle between the resultant stress and normal stress in angle of oblique.

 

EXAMPLE:

In the Mohr’s circle shown below σx and σy are tensile. Shear stress  Lemda xy is clockwise to stress plane σx and anticlockwise to plane σy.

Observation from Mohr’s circle:

Given data:               σx = OJ is tensile stress on one plane.

                                   σy = OK is tensile stress on other plane.  is shear force on the planes.                     

                                   θ – Angle of inclination. Result from Mohr’sCircle:                

                                   CM = radius of Mohr’s circle 

                                   λmax It is the maximum shear stress.

                                  QP = σt Shear stress at the point.

                                  ON = σn Normal stress at the point.

                                  OP = σR Resultant stress at the point.

                                  OG = Minimum principal stress

                                 OH = Maximum principal stress.

                                 POG = angle of obliquity.

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