Mohr

Mohr is a surname of German origin. It derives from the word mohr (also spelled Moor), historically used to describe people associated with the moors or darker complexion, and it subsequently became a general surname in German-speaking regions. Over time, the name has appeared in records across Europe and is carried by individuals in many fields. The spelling Mohr is a common modern variant.

In engineering, Mohr's circle is a graphical method named after Christian Otto Mohr (1835–1918). It is used to analyze and transform planar states of stress. The method plots normal stress on the horizontal axis and shear stress on the vertical axis for different orientations; the locus of possible stress states forms a circle. From this circle, principal stresses, maximum shear stresses, and rotated stress components can be read off, and the effects of rotation on the stress state visualized. Generalizations exist for three-dimensional stress states, including Mohr's sphere, and the technique remains a standard teaching and design tool in civil, mechanical, and aerospace engineering.

The surname Mohr appears in various contexts beyond the circle, reflecting its broad historical and geographical usage in German-speaking communities. Christian Otto Mohr is the best-known figure associated with the term Mohr's circle, but the name itself encompasses a wider set of individuals and historical references.