r_outer 1[m] Outer radius thickness 0.1[m] Thickness r_inner r_outer-thickness Inner radius r_mid r_outer-thickness/2 Radius of shell midsurface in geometry r_hole 0.15[m] Hole radius length 4[m] Length of segment nominal_stress 10[MPa] Target stress p_int nominal_stress*thickness/r_inner Internal pressure f_extp -pi*r_hole^2*nominal_stress*thickness/r_mid External load from pressure