flange alluminio

[uappo]

Hello, everyone.
I present the problem: bolted coupling of two flanges, one in aluminium and the other in steel; on that in aluminum has been recalculated the shape of the bolt rosette for excess of the tightening moment. how do you calculate the force necessary to produce such deformation in order to establish with which pair the bolts have been tightened?

 

[gerod]

We're in a plastic environment.
We need to know the behaviour of the material in order to tell how much strength it has deformed.
If you know this, it's simple.
If you were on the line, that would be pretty trivial.

 

[SOLID]

if you know the depth of the footprint you could proceed very quickly with a fem contact analysis (maybe using the marc).

 

[uappo]

Unfortunately we do not have fem programs so I was trying to tamper.
the depth of the footprint is 1-2 tenths. I tried with the theory of plastic deformations but I get really high values that sound a little weird.
the flange material is en ac-45300 t4 with a yielding load of 120 mpa and the rosette has 50 mm and = 28 mm (for m27 screws). we indicate as tightening couple 50 nm.
Thank you very much

 

[cesius79]

emmm...maybe my answer is very stupid but do you have flanges to throw? You could make attempts on a ruined flange or to throw and make attempts: I don't think you'll come out. .
Perhaps if you have no fem another way it can be thin the hardness..record how do you determine it?magari on the test theory brinnel or similar you can trace to something. .

 

[uappo]

It is a proof that we will definitely do, it was to have a theoretical support to make an arelation.
I thought about the hardness but I don't know how to connect the brinnel hardness made with a ball and the penetration performed by a rosette.