Tasks contd...

R$3\mathrm{.}2$:

Semi$-$circular grooves of radius $r$ must be milled as shown in the top and bottom portions of a steel member.

Using an allowable stress of $60$ MPa, determine the maximum bending moment that can be applied to the member when the radius $r$ of the semi$-$circular grooves is:

$($a$)r=9mm.$

$($b$)r=18mm.$

Fig. R$3\mathrm{.}2$: A bar with grooves under moment.