From TransAtlantic Aerospace:
This tool will calculate and display Mohr's circle as well as the principle and transformed stresses for any given 2D stress tensor. To use:
1) Enter the full 2D stress tensor (sig x, y, and xy) at the reference (0 degrees) angle in the boxes where it says 'Input Stress Tensor at 0 deg'. The tool will then draw Mohr's Circle for this state of stress and the reference stresses will be indicated with a red line. The principal stress data can then be found in the 'Invariants' section.
2) The stress tensor for any given theta can be calculated and plotted in red on the Mohr Circle either by a) directly entering a value (in degrees) for theta were it says 'Tensor at Specific Theta' or by increasing/decreasing the value of theta using the +Theta / -Theta buttons located next to the chart.
3) If the Mohr Circle for a given stress tensor appears too small on the chart, use the 'Zoom' button located next to the chart to re-size.
This program is free to use and distribute at no charge subject to the inclusion of the copyright notice.
For comments and/or questions please contact firstname.lastname@example.org