Changes

(Wieland)

The fatigue strength is a measure of maximum alternating bending force, symmetrical to the zero position, which a sample – for example a relay spring – can be exposed to for an “unlimited” number of cycles without breaking. (Rule of thumb: Fatigue strength = 1/3 of Tensile strength). The measurement is conducted using so-called Woehler– diagrams . With increasing bending force 7 the number of alternating cycles before breaking decreases. Above 10 cycles the influence of further cycling numbers becomes insignificant and therefore 7 the force value reaching 2x10 cycles can be used to define the fatigue strength.