Summary

This Toolbox app calculates values of the factor $K_{tux}$ which are used to determine the tensile rupture load of a lug under axial loading, see Section 1.3.2.1 of ESDU 91008.

The axial load to cause failure of a lug is given by the equation

$P_{tux}$ = $K_{tux}$ $f_{tux}$ ($W$ - $d_h$) $t$

The lug axial load tensile efficiency factor, $K_{tux}$, is effectively an inelastic stress concentration factor which was obtained from an empirical approximation supported by experiment. A detailed development of the theory is given in Derivation 3 of ESDU 91008 and this has been adapted to provide the program provided here.

The theory assumes that an empirical stress distribution across the net width of the lug having a maximum value coincident with the elastic stress concentration factor, $K'e$, will provide a strain distribution that will remain unchanged through plastic deformation to failure. The factor $K_{tux}$ is obtained by integrating the inelastic stresses corresponding to that strain distribution when the point of maximum stress concentration (at the hole perimeter) has the value of the material ultimate stress and corresponding strain, $f_{tux}$ and $e_{tux}$. It is assumed that the effect of the lug/pin fit and pin bending are included in the value of the stress concentration factor, $K'e$, used.