I am measuring the factors of safety for a side plate for a crane. One version of the side plate has a minimum diameter of 6.531, the "MODIFIED" is bored out to 6.534. Typically, I would expect that the factor of safety on the "ORIGINAL" plate to be greater (stronger) than the modified; however, in every case with playing around with the fixtures, force directions, etc., the plate with the larger hole has a greater factor of safety. This does not make sense to me, since there is less material in the MODIFIED model.
The crane is a 94-ton crane.
The upper hole is where I've been fixturing it.
The force is focused on the lower bore, which is the dimension that is being modified. I've made it 94,000 lbs (since there are two plates in the assembly, I made the assumption they are equally distributing the weight), and directed downward by using the Top Plane.
Any help would be great. Thanks.