CATIA V5 FEA - Objective Error (%)

[amitpatel87]

Morning all,

First Post here.

My question is with regards to adaptive meshing in CATIA V5 Generative Structural Analysis workbench.

When I create an adaptive mesh, I understand the objective error is essentially the measure of the strain energy in each element. I was wondering how exactly is the Objective Error (%) calculated?

Thanks

 

[loki3000]

offtopic:

http://www.eng-tips.com/viewthread.cfm?qid=352234

please see the last response in the thread. any idea when will v6 have SR1-type workbench?

 

[KevinDeSmet]

Yours is a good question, can't seem to find this in the help file. It's a stark reminder of how much of a "black box" FEA solution CATIA's workbenches truly are.

CATIA says: "Objective error (%): lets you specify the objective error of the selected mesh part."
Oh yeah! Knowledge is so good!

 

[itsmyjob]

objective error is not computed, it is for you to define.

it is used when you do computation with adaptability. All is explain in the online doc. With adaptive computation, the mesh will be modified in order to get the error (or sensor) to a define value.

You do a large mesh, this is quick and fast but error might be above 20%.
CATIA will iterate computation until it reach your target (if possible).
Then you will have a result in the desired range.

Or you can refine you mesh manually and do the computation, check error % then iterate manually... it will take you longer to get the result closer to what you need.

Eric N.
indocti discant et ament meminisse periti ​

 

[amitpatel87]

Thanks for the reply guys.

itsmyjob, thanks for the reply. I am aware of where and how to use it. I understand an error % of around 10% is a good target to aim for. However I am unsure what exactly it measures?! It can not just be a generic value, it must have some meaning. Is it maybe that one or more elements contains over 10% of the total values?! Not really sure what the % error measures. CATIA must do some form of calculation in the background in order to compute it as it is mathematically based.

Thanks for the replies.