Since the centre of the Mohr stress circle is always located on the σ-axis, each Mohr stress circle has two points of intersection with the σ-axis. The normal stresses defined through these points of intersection are called the principal stresses, whereby the larger principal stress – the major principal stress – is designated as σ1 and the smaller principal stress – the minor princi- pal stress – is designated as σ2. If both principal stresses are given, the Mohr stress circle is well defined.