Question

Calculate the shear stress (lbf/in^2) for a given normal stress (lbf/in^2) that is applied to a material with a given cohesion (lbf/in^2) and angle of internal friction (degrees). (See MohrCoulomb failure criterion

Answer 1

MOHR-COULOMB FAILURE CRITERIA:

In 1900, MOHR-COULOMB states Theory of Rupture in Materials which defines as “A material fails due to because of a critical combination of normal and shear stress, not from maximum normal or shear stress”. Failure Envelope is approached by a linear relationship.

If you can not understand the below symbols see the attachment below

 f   f ()  

Where:      f = Shear Stress on Failure Plane  

       ´= Normal Stress on Failure Plane

 See the graph in the attachment

For calculating the shear stress, when Normal stress, cohesion and angle of internal friction are given. Use this formula:   shear stress =  f  c   tan 

Where,  

• f  is Shear Stress on Failure Plane

• c  is Cohesion

•  is Normal Total Stress on Failure Plane

•  is Friction Angle