Ear Lug Design

For any particular vessel the algebraic formulas might be written to obtain the forces, etc, at any given angle. Calculus could then be used to determine the formulas for the maximum and minimum values. This could be done easily to determine the angle at which any particular force component is a minimum or maximum. See the COMPRESS Users Manual, Appendix C for the force distribution formulas (which are derived from simple equations of static equilibrium).

However, because the stresses are determined by the WRC-107 or other analysis the problem may not lend itself to such manipulation by the calculus. In any case, writing and solving these equations for all vessels with all possible permutations of construction, nozzle locations, etc, would be quite impractical.

COMPRESS performs these calculations by using a sort of brute force method for this problem. The lifting forces acting on the vessel and the lifting and tailing lugs, and the stresses existing in the shell and the lugs, are calculated internally in the program for all angles between 0° and 90°, inclusive, at one degree increments. The results are reported in the summary tables for the 15° increments and the angles that correspond to the maximum stresses in the shell and lugs are reported to the summary tables as well. Detailed calculations are provided for the "worst case" angle for each component.

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Codeware Technical Support