A simply-supported beam has a circular cross section with a diameter of

25.0mm

, and length of

400mm

. The center of the beam contains a weld that fatigues with a Basquin's law given by

\\\\sigma _(ar)N_(f)^(0.14)=800MPa

. The weld has a yield stress of

200MPa

and a tensile strength of

400MPa

.\ a) If a fully-reversed point load of amplitude

4.0kN

is applied

100mm

from one end of the beam, what is the life-time of the weld?\ cycles