One frequently used term is the stress ratio ${\displaystyle R={\frac {\sigma _{min}}{\sigma _{max}}}}$. This measure offers a convenient way to classify different stress constellations, as follows:
• ${\displaystyle R=1\Rightarrow }$ constant stress
• ${\displaystyle R=\pm \infty \Rightarrow }$ no tension, only cyclic compression
• ${\displaystyle R=0\Rightarrow }$ no compression, only cyclic tension