Ktru or the transverse efficiency factor determines what the allowable load of the lug will be with respect to transverse stress. This value is determined by figure 9-8 in AFFDL-TR-69-42. The required unitless geometric ratio is havg/D, please see calculated geometry for a description of havg/D. LugCalc™ automatically queries the chart to determine the value of Ktru that coincides with the supplied havg/D ratio. Range for havg/D is from 0.0 to 1.6. Any value for havg/D outside this range will be assigned the last chart value before exceeding the documented range.

Transverse Failure Mode

Sometimes it may desirable to adjust the automatic output if the engineer or designer wishes to use a lower or higher value for experimentation or to match an existing value that was calculated manually. To do this, the user uses the K Offset % feature to manually adjust the automatic value up or down linearly by the desired percentage. When set to 0.0, no adjustments are made.

Ktru Screenshot

LugCalc will automatically calculate Ftru (allowable stress) and Ptru (allowable load) for the user displaying the equation used. The equations for Ftru and Ptru change depending on the nature of the material properties. LugCalc™ will automatically select the correct equation for you. See AFFDL-TR-69-42 for further detail.

Ktru AFFDL-TR-69-42