The link below provides a collection of slides used to explain Mohr’s circle in an undergraduate mechanics course at the University of Utah. If you use a Mac, it is unlikely that these will render properly (so go sit at a PC in your university computer lab to look at them). Make sure to use slideshow mode, as these have many animations!
MohrCircleFiles (zip file contains two PPT lectures and one Mathematica file)
General Mohr's Circle for 3D Stress State
Have you ever had a stress state and wanted to simply get the principal stresses without finding a web applet to do it for you? Or maybe you want to know what the deviatoric part of the stress is without finding and using a copy of MATLAB or Mathematica to do the matrix operations for you? This script was written to help answer those questions in as little time as possible with an intuitive command line input syntax.
This script was written in Python (www.python.org) and makes use of the NumPy module (www.numpy.scipy.org). Python is a fairly platform independent programming language with more and more programs being dependent on it on all platforms. The NumPy module adds significant scientific computation power to the language by adding N-dimensional matrix support, matrix operations, LAPACK functions (matrix inverse, eigenvalue and eigenvector decompositions, etc.), among other things.
You can download the script here.
A self-study refresher with interesting tidbits such as Pole Point and how to do Mohr’s circle for nonsymmetric matrices — very useful for quickly doing a polar decomposition! (Last posted 2003, but considerable work has been performed recently to incorporate Mohr’s circle as part of the opensource VTK for visualization in finite element simulations).
You may download the rest of the document here.