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Engineer associated with Mohr's circle and strength criteria for stressed materials.

A frictional shear-strength approximation $|\tau |=c+{\sigma }_n^{\prime }\tan \phi$, with cohesion $c$ and internal friction angle $\phi$. Effective compression increases shear resistance. A separate tensile cutoff is generally needed at low confinement. The names refer to Christian Otto Mohr and Charles-Augustin de Coulomb.

A geometric representation of resolved normal stress and shear stress. For two principal stresses, its centre is $C=({\sigma }_1+{\sigma }_3)/2$ and radius $R=({\sigma }_1-{\sigma }_3)/2$. A physical plane-normal rotation by $\theta$ corresponds to $2\theta$ on the circle, with the sense depending on the shear-sign convention. Named for Christian Otto Mohr.