Bolted connection - member stiffness 1

[LuRu]

Well, hei!


A design engineer have asked me to check a flange (please see pic 1). He wants to know what is going to break first eventually: the flange or the bolts.

Lets say under a bending moment, statically.

So... I was wondering how to estimate the stiffness of the connected parts: 1, 2, 3, flange. The memebers 2,3,flange are connected in parallel: 1/k=1/k2 + 1/k3 + 1/kflange is valid. But what about the member 1?

I am so confused and curious at the same time.

Would it be right to use Ansys to estimate the stiffness of the multilayer member?

What I do is to apply a compression force simulating the bolt pretension (please see pic 2). Get deflection and then calculate the stiffness.

I get reasonable magnitudes and all seems fine.

But would like to hear if my reasoning is right.

Thanks.

https://files.engineering.com/getfile.aspx?folder=bc205b22-62e6-40ca-a607-b26ade023519&file=pic1.JPG

https://files.engineering.com/getfile.aspx?folder=0a19a9eb-b0c5-479c-a680-f39acc30725e&file=pic2.JPG

 

[desertfox]

Hi LuRu

You can get info on stiffness of clamped parts here:-

https://www.roymech.co.uk/Useful_Tables/Screws/Preloading.html

However I see a problem with your joint configuration:- if part one (blue bearing) doesn't overhang part3 then part 2 (grey component) cannot clamp part 1 in place.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein