Mohrs Circle 1

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.