 Mohr's circle

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.

Mohr's Circle is a graphical representation used in the field of mechanics and civil engineering to analyze the state of stress at a point in a material. It provides a way to visualize the relationships between normal and shear stresses acting on various planes through that point, making it easier to understand complex stress states.