Is it possible to do fatigue analysis with Inventor? 5

[EngineerInv]

My case: Cyclic repeated loading on an item.

Can I use Inventor to tell me if it will break after a period of time as a result of metal fatigue?

 

[rollupswx]

No

 

[FeX32]

Some FEA packages do this. You may be able to find one that can "add on" to inventor.
But as the above says. You can't do it directly with inventor. Inventor is strictly CAD related.


Fe

 

[rollupswx]

Inventor is strictly CAD related.

Wrong, ohhhh so wrong.
Inventor Simulation or Inventor Professional does part and assembly and frame linear FEA and advanced Dynamic Simulation - it just doesn't to fatigue analysis or non-linear and some other types of analysis.

Autodesk does have other software that does fatigue analysis.
Autodesk Simulation (was Algor) for one.

 

[FeX32]

Yes, you are correct. Sorry about that. I just don't use Inventor for anything but CAD...
Every software company nowadays has FEA ect... I guess I should assume this haha.

In no way do I endorse FEA to the max. Many times users misuse FEA packages without understanding anything.


Fe

 

[rollupswx]

I teach FEA in Inventor, SolidWorks, Algor and Pro/E

In any software FEA must be validated with physical testing.
Once you have a good validation THEN you can use for predictive purposes on very similiar problems. But once the problems become too dissimilar then it might become completely invalid.

 

[FeX32]

Very true. That analogy and methodology is perfect in my eyes.


Fe

 

[GregLocock]

You could use any FEA to establish the hot spots for each load case, then use those stress levels in your choice of manual calculation to establish a fatigue life. The fancy FEA/fatigue packages don't really do a whole damn lot more than that, just make it much less boring to do. The answers will still be pretty dubious unless you are interested in predicting a fatigue life on a test rig.

Cheers

Greg Locock


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[EngAddict]

Last I checked Inventor Simulation doesn't show stress intensity (tresca) which is required by some fatigue codes. Are you expected to calculate it manually to find your geometric stress?..

IMO Inventor should only be used for CAD, while dynamic simulation is useful, the FEA environment is not.

 

[EngineerInv]

Do any of you guys know of a good link/website that describes how to calculate fatigue analysis and the principles behind?

 

[rollupswx]

Do you have access to Autodesk Simulation (was Algor)?
Students can download it for free from

http://www.autodesk.com/edcommunity

there might be a trial download for those who are not students.

 

[EngAddict]

I would suggest you source some fatigue codes, like PD5500 Annex C, ABS Design Rule for Offshore Structures (should be a free download), ASME VIII-2, etc. These are mostly offshore or pressure vessel standards but are applicable to any fatigue analysis. They will give you guidelines for locating your stress, requirements for modelling, curves to compare your stress to and cumulative damage equations (miners rule). They also suggest design rules for fatigue, like integral reinforcement, minimum fillets and partial pen welds, full pen welds with dressed toes where ever possible, etc.

After that you can dig a little deeper with books and papers for things like the effect of stress direction, uniaxial, multiaxial, etc. When tresca is better and when principal stress range is better, etc. This last point is important because some codes will only use one or the other, but in some situations can be unconservative. Notice that some codes also use full stress range while others only use stress amplitude.

After that you may want to dig into fracture mechanics.

 

[GregLocock]

The simplest worthwhile discussion I know is in Ashby and Jones "Engineering materials" or some such.





Cheers

Greg Locock


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