We have updated the lug methods for our engineering textbook and one of the best explained and best laid out classic lug analysis comes from the US Airforce Stress Manual, AFFDL-TR-69-42 and is explained in our online textbook here. We have used this as the basis for our lug analysis spreadsheets. All of the curves are fully digitized. There is a spreadsheet for each of the individual failure modes :
and there is a fully automated sheet that does all of the calculations and calculates the interaction:
There is also a spreadsheet that calculates the complex pin bending effect.