Tools › Structures › Joints › Lug Strength › Example
AFFDL-TR-69-42 Section 9.14.1.3: design of a double-shear lug joint for 37,900 lb
| Tool | Lug Strength |
| Source | Maddux, G. E., Vorst, L. A., Giessler, F. J., and Moritz, T. (1969). Stress Analysis Manual. AFFDL-TR-69-42, Air Force Flight Dynamics Laboratory, Wright-Patterson Air Force Base, OH. Section 9.14.1.3, Figures 9-14 to 9-16. |
| Level | Professional |
Problem
Size the pin and lugs of the double-shear joint of the Section 9.6 example for an ultimate design load of 37,900 lb with 0.125 in bushing walls and a pin-to-lug density ratio of 2.83, following the manual's design procedure: the allowable bearing stress parameter K, the shear-bending ratio R, the pin diameter from the shear and bending modes, the optimum e/D, the lug thicknesses and the reduced width of the male lug.
Inputs to Enter
- Check the Design box; P_des = 37,900 lb, t_B = 0.125 in, ρ_p/ρ_L = 2.83 (the form's defaults)
- Lug and pin materials of the Section 9.6 example (default inputs); Advanced mode
Answers
- K = 1.02 from Figure 9-14 at 2.83 (manual 1.02); R = 3.4 (eq. 9-32, manual 3.4)
- D_p = 0.741 in by eq. 9-35 (manual 0.741); optimum e/D = 1.24 from Figure 9-15(b) (manual 1.24)
- t_2 first approximation 0.654 in (manual 0.654); D_p = 0.755 in by eq. 9-34 (manual 0.755); standard pin 0.750 in
- Final t_2 = 0.646 in (manual 0.646); male lug Figure 9-16 abscissa 0.762, reduced e/D 0.97, reduced width w_2 = 2.23 in (manual 0.762 / 0.97 / 2.23)
Notes
Reproduced through the Design checkbox on the default (Section 9.6) inputs; the female lug's third digit differs from the manual through the reading of Figure 9-4. The 9-34 pin exceeding the 9-33 pin sends the design to the bending mode as 9.14.1.1 directs.