turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Navigation
- Simcenter
- Forums
- Blogs
- Knowledge Bases

- Siemens PLM Community
- Simcenter
- 3D Simulation - Femap Forum
- Percentage Error - Uncertainty Analysis

Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

10-05-2017 05:04 AM

Hello everyone,

My question might be out of forum.

However I am just seeking advice

As I have performed experiment as well as FEA and CFD (Using FEMAP and TMG) and now I want to see the percentage error.

Does anybody know how to do uncertainty analysis, any software recommendation or any advice would be very helpful for me?

Many thanks in advance for your support and help.

3 REPLIES

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

10-05-2017 05:24 AM

Dear Varum,

Most of the answer is in your hands: you have an element library & different analysis types, and also you can play with mesh densities, then use all of those variables an compare results.

- Not only mesh the problem with 3-D solids, also use 2-D mesh or if available 1-D beam elements, solve and compare results.
- At the same time, play with mesh size and compare result: beam elements are discrete elements, the answer is the same not matter the mesh density used, but for shell & solids the mesh density is critical. The target: you need to arrive to a mesh undependent model, ie, the answer should not depend of the mesh density. The solution is convergent when the difference between two analysis whit double DOFs is not bigger than a 5% or so.
- Also, play with analysis types, and compare results: linear static analysis give an answer, yes, but real life is always nonlinear (by geometry, material & BCs), then linear static is a simplification of the real life. If the nonlinearities are not severe, then a linear static is enough, but you need to judge the level of nonlinearity of a problem, the way is run both analysis & compare results, OK?.

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director

IBERISA • 48004 BILBAO (SPAIN)

WEB: http://www.iberisa.com

Blog Femap-NX Nastran: http://iberisa.wordpress.com/

IBERISA • 48004 BILBAO (SPAIN)

WEB: http://www.iberisa.com

Blog Femap-NX Nastran: http://iberisa.wordpress.com/

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

10-05-2017 05:47 AM

Thanks you Blas for the answer.

I understood what you described above.

But my points is how to perform it.

In relation to your above statements, well, my model is in STL Format so cannot vary the mesh size and elements. So cannot do much variation in mesh. But I am using solid linear tetra 4 noded elements

However, I have performed crushing analysis on porous material by choosing elastic – plastic material model.

So now, I have experimental data which consist stress vs strain value and FEA von misses stresses, strain, displacement results.

Now, I wanted to compare experiment vs simulation results to see how much percentage of error occur.

My points is how to perform it, Shall I use basic uncertainty equations or statistics or is there any other way to do.

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

10-05-2017 06:10 AM

Hello!,

First at all: TET4 is a "awful" element type, is a constant strain & constant stress element, each point internal in the element has the same stress & strain, then its use should be avoided always, please consider using high-order TET10 elements, in FEMAP you can convert your mesh using **MODIFY > UPDATE ELEMENT > LINEAR/PARABOLIC ORDER** command. In severe nonlinear analysis the use of high-oder elements is mandatory, and preferable HEX elements instead TET ones.

Best regards,

Blass.

Blas Molero Hidalgo, Ingeniero Industrial, Director

IBERISA • 48004 BILBAO (SPAIN)

WEB: http://www.iberisa.com

Blog Femap-NX Nastran: http://iberisa.wordpress.com/

IBERISA • 48004 BILBAO (SPAIN)

WEB: http://www.iberisa.com

Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Follow Siemens PLM Software

© 2017 Siemens Product Lifecycle Management Software Inc