FEA or Hand Calculation

[lenovo1]

I have been carrying out calculations of some load bearing mechanical equipment. I have taken a (very) pessimistic approach to the calculations, assumptions include that only a fraction of the fasteners connecting the sub-components are loaded, only a small portion of the threads are loaded, making the loads artificially higher than they actually are etc.

I am debating whether it is worth carrying out FEA to back up my hand calculations. I would not be looking to use the FEA to refine the design to reduce weight etc, it would just be to confirm that all my calculated stresses are within the allowable limits. The key for me is that all of the RFs have a reasonable margin above 1.

With all the pessimism that is being applied in the calculations, would it be worth spending the extra time carrying out the FEA?
How accurate is FEA when assessing bolts/fasteners?

Also, separate to the FEA query, when carrying out shear stress calculations on threads, should SCFs be applied?

Thanks to all that respond.

 

[corus]

If you're using the same assumptions then you're likely to get the same answer. FEA would be useful if you're considering secondary effects above and beyond a simple hand calculation, ie. the distribution of loads due to the relative stiffness of components, and the effect of contact on the load distribution, say.

 

[DanStro]

I always try to use more than one method/tool to confirm result. So if you are reasonably proficient at using FEA that I would say that it is worth it. If you are not too familiar with it then it might be more trouble than it is worth because of either the time it will take to model the system and/or not interpreting the results correctly. If that is the case then maybe get someone with proficiency in FEA modelling to do it.

Han primo incensus