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Simulation of simple cantilever using A325 structural bolts - a few questions on connector input

Question asked by Dave Krum on May 8, 2020
Latest reply on May 11, 2020 by Dave Krum

Hi all,

I'm trying to learn what I can about the simulation module while doing my normal SW work.  I usually only model but a few shop projects came up recently for fixtures and I thought I'd start messing around with this package again.  I've dabbled with it for years off and on but usually only for the globally bonded contact weldments (all welded stuff), no assembled components within an assembly which gets alot more complicated as I'm learning.  Below I modeled a simple cantilever bracket.  The weldment is set to global bonding for all of the tests, then the arm is bolted to it with (4) 5/8-11 A325 bolts.  The weldment is fixed and I've applied a 3000# vertical load at the end hole.  I ran 3 different tests to compare the stresses and deflection.  I realize that you really need to know what you are doing and have an understanding of all the intricates but I am just trying to learn the basics.  I am a bit confused with the "connection" contacts and what to key in for some of the fields for both the pin and bolt options.

 

Below I've summarized:

Test 1: (entire assembly globally bonded) - results are 41k max stress & .32" deflection

 

Test 2: (globally bonded weldment; contact surfaces for coincident arm face to weldment face with "no penetration"; (4) pinned connections) - results are 61k max stress at inside upper pin & .35" deflection

also have this for all 4 pins but something can't be right because the pin/bolt check with 3 need attention but 4th isn't mentioned?

 

Test 3: (globally bonded weldment; contact surfaces for coincident arm face to weldment face with "no penetration"; (4) bolts for connection - results are 48k max stress at inside upper bolt & .56" deflection quite different from tests 1 & 2 - because the bolt parameters are not set correctly for starters? or is the pin parameters incorrect?

and the bolt settings (again I don't think I have all the info here; I do have charts for 5/8-11 structural bolts - 19kips pretension, 200 ft.pounds average torque to get to, 85ksi proof strength, 92ksi yield strength, 120ksi tensile strength but which do I key in where? Is The pre-load value in lbf.in supposed to be the 200 from above for pretensioning the bolt or 19kips?)

Lastly, I get the error about no pre-load because I have it set to zero, how much does it matter for a ballpark?  Does this just mean the bolt is not getting torqued in the connection?  I usually just hit YES to continue

 

Thanks in advance for any help / suggestions!  I've attached the zip of assembly. 

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