a) $F_{s\max} = F_i + \frac{F_L}{1 + \frac{k_f}{k_s}}$ , $F_L = 942.5 \, \text{N}$ , $F_i = \{d_i = 4.917\} = 3418 \, \text{N}$

k _ {s} = \frac {A _ {s} E _ {s}}{L}, \quad A _ {s} = \frac {\pi d ^ {2}}{4} = 2 8. 2 7 \mathrm {m m} ^ {2} \rightarrow k _ {s} = 4 8 5 3 8 \mathrm {N / m m}k _ {f} = \frac {A _ {f} E _ {f}}{L}, \quad A _ {f} = \frac {\pi}{4} \left(\left(N + 0. 3 L\right) ^ {2} - D _ {h l l} ^ {2}\right) = 1 6 2 3 \mathrm {m m} ^ {2} \rightarrow k _ {f} = 9 4 6 9 9 4 \mathrm {N / m m} F _ {s \max } = 3 4 6 4 \mathrm {N}