고체역학 (Gere) — Stresses in Beams (Basic Topics): Problem 5.6-4

5.6-4 A fiberglass bracket $ABCD$ with a solid circular cross section has the shape and dimensions shown in the figure. A vertical load $P = 40\text{ N}$ acts at the free end $D$. (a) Determine the minimum permissible diameter $d_{\min}$ of the bracket if the allowable bending stress in the material is $30\text{ MPa}$ and $b = 37\text{ mm}$. Note: Disregard the weight of the bracket itself. (b) If $d = 10\text{ mm}$, $b = 37\text{ mm}$, and $\sigma_{\text{allow}} = 30\text{ MPa}$, what is the maximum value of load $P$ if vertical load $P$ at $D$ is replaced with horizontal loads $P$ at $B$ and $D$ (see figure part b)?