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ulvi_r
Posts: 17
Registered: ‎09-08-2012
Message 1 of 7 (520 Views)
Accepted Solution

Frame Analysis - Trestle (SWL 2t)

520 Views, 6 Replies
09-11-2012 02:43 AM

hi mates,

 

I've attached file. This is trestle and SWL(safety work load) is 2T.How can understandble that this load is going to be withstand by trestle.

 

Thanks in advance.

If you scroll down to the RESULTS section, you'll see all of the maximum forces, stresses, moments etc, that the Trestle can withstand. Not only that, but it gives the results about different axis.

 

Please bear in mind that ALL computer generated FEA must be used alongside hand calcs (which really should be done beforehand to give you an idea of what the FEA should generate).

Thanks for repling,

 

Just one question else, as well as i see, in the reaction force column  Fx =18575.465 N, but in Static Result Summary

Fx = -13851.955 N what is the differences between them? How can i exactly come to conclusion that, this frame is ok for this load or not? Please clarify this for me.

 

Thanks in advance.

It might be worth your while taking a look here and also look through the tutorial for Frame Analysis.

 

http://wikihelp.autodesk.com/Inventor/enu/2012/Help/2098-Frame_An2098/2099-Frame_An2099/2105-Visualiz2105

Valued Contributor
PhilSaw
Posts: 65
Registered: ‎06-28-2011
Message 2 of 7 (512 Views)

Re: Frame Analysis - Trestle (SWL 2t)

09-11-2012 03:03 AM in reply to: ulvi_r

If you scroll down to the RESULTS section, you'll see all of the maximum forces, stresses, moments etc, that the Trestle can withstand. Not only that, but it gives the results about different axis.

 

Please bear in mind that ALL computer generated FEA must be used alongside hand calcs (which really should be done beforehand to give you an idea of what the FEA should generate).

Please click "Accept as Solution" if this response answers your question.
-------------------------------------------------------------------------------------
Autodesk Inventor Professional 2012
Windows 7 Professional, 64-bit (Service Pack 1)
Intel(R) Core(TM i7-2600 CPU, Quadro 2000 graphics card, 8G RAM
Contributor
ulvi_r
Posts: 17
Registered: ‎09-08-2012
Message 3 of 7 (504 Views)

Re: Frame Analysis - Trestle (SWL 2t)

09-11-2012 03:33 AM in reply to: PhilSaw

Thanks for repling,

 

Just one question else, as well as i see, in the reaction force column  Fx =18575.465 N, but in Static Result Summary

Fx = -13851.955 N what is the differences between them? How can i exactly come to conclusion that, this frame is ok for this load or not? Please clarify this for me.

 

Thanks in advance.

Valued Contributor
PhilSaw
Posts: 65
Registered: ‎06-28-2011
Message 4 of 7 (477 Views)

Re: Frame Analysis - Trestle (SWL 2t)

09-11-2012 07:56 AM in reply to: ulvi_r

It might be worth your while taking a look here and also look through the tutorial for Frame Analysis.

 

http://wikihelp.autodesk.com/Inventor/enu/2012/Help/2098-Frame_An2098/2099-Frame_An2099/2105-Visuali...

Please click "Accept as Solution" if this response answers your question.
-------------------------------------------------------------------------------------
Autodesk Inventor Professional 2012
Windows 7 Professional, 64-bit (Service Pack 1)
Intel(R) Core(TM i7-2600 CPU, Quadro 2000 graphics card, 8G RAM
*Expert Elite*
Inv_kaos
Posts: 728
Registered: ‎07-26-2007
Message 5 of 7 (452 Views)

Re: Frame Analysis - Trestle (SWL 2t)

09-11-2012 06:34 PM in reply to: ulvi_r

ulvi_r wrote:

How can i exactly come to conclusion that, this frame is ok for this load or not? Please clarify this for me.


What structural code are you working to?

 

Since you are running FEA and therefore dealing with actual stresses based on unfactored loads you will likely be using a working stress method. Since these are pretty much the same in any country you could use 0.6*Fy as your allowable for tension, 0.75*Fy for bearing stress, 0.66*Fy for bending or 0.75*Fy for bending of a solid section, 0.45*Fy for shear and the lateral buckling you will need to check manually by working out your effective length, then your slenderness ratio and compare it to the tables (or whatever particular method your code uses). For compression I would refer you to the relevant code because it depends on loading and member geometry.

 

You also need to consider combined stress which you could check manually to code or compare to something like 90% of yield, but that is not code specific. So basically is it "ok for load or not" depends on how you must justify your pass / fail criteria. To keep it simple, if your factor of safety is high then it will likely pass without too much further checking but you will over design your frame. If you are cutting it closer to the limits then you will need to break it down into more detail in those areas. This factor of safety is not the same as buckling load factor though and so buckling should be checked manually where applicable.

 

If you design any of your connections as moment resisting then you should use the bending moment at these connections to check your welds or bolted connections by hand. Again you can be conservative here and oversize your welds or base it off previous similar designs that proved to be fine. But generally if the latter was the case then you would not be running FEA and therefore have to justify your results.

 

Hope it helps.

Please mark as "Accept as Solution" if it answers your question or "Kudos" if you found it useful.
---------------------------------------------------------------------------------------------------------------------
Stew, AICP
Inventor Professional 2013, Autodesk Simulation Multiphysics 2013
Windows 7 x64 Core i7 32GB Ram FX2000
Contributor
ulvi_r
Posts: 17
Registered: ‎09-08-2012
Message 6 of 7 (408 Views)

Re: Frame Analysis - Trestle (SWL 2t)

09-12-2012 11:33 PM in reply to: Inv_kaos

Thanks for repling mate,

 

Generally I do hand calculation alonside with it and in hand calculation Permissible normal stress for upper stiffener is taken as 1440  (kg/cm2)  plus Tension determination - σP  arising in upper stiffener of Support Trestles is   (kg/cm2).That means it is ok for construction.

 

Please clarify for me where this things to find out in attached file.I don't mean  same numbers, I mean the tension which arising upper stiffener (of course it is not going to be the same with hand calculation becouse of safety factor has not been taken in account).

 

Thanks a lot in advance. 

*Expert Elite*
Inv_kaos
Posts: 728
Registered: ‎07-26-2007
Message 7 of 7 (400 Views)

Re: Frame Analysis - Trestle (SWL 2t)

09-13-2012 03:09 AM in reply to: ulvi_r

It would help if I could see a picture of your model.

Please mark as "Accept as Solution" if it answers your question or "Kudos" if you found it useful.
---------------------------------------------------------------------------------------------------------------------
Stew, AICP
Inventor Professional 2013, Autodesk Simulation Multiphysics 2013
Windows 7 x64 Core i7 32GB Ram FX2000
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