A look into mesh density IN THIS WEBINAR: PRESENTED BY: Mesh - - PowerPoint PPT Presentation

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Accuracy vs. Speed A look into mesh density IN THIS WEBINAR: PRESENTED BY: Mesh refinement Andrew Nelson Discussing higher order elements Stress Engineer Examining analytical error and Structural Design and Analysis

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IN THIS WEBINAR:

Mesh refinement
Discussing higher order elements
Examining analytical error and

quantifying benefits

Accuracy vs. Speed A look into mesh density

Andrew Nelson

Stress Engineer Structural Design and Analysis aNelson@structures.aero

PRESENTED BY:

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Mesh Refinement

Refining a mesh is a simple process
Stress concentrations
Benefits and drawbacks
Results accuracy
Computation time
We will look at a basic example

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Plate with Hole

LINEAR Mesh Size (in) DOF Peak Stress (psi) % Error 0.2 4440 1354 32.3 0.1 16992 1705 14.75 0.05 66408 1919 4.05 0.025 262512 2006 0.3 PARABOLIC

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Higher Order Elements

Parabolic elements
Different that just a finer mesh
Benefit is second order shape functions
Most useful with bending
We create these elements with mid-side nodes

Linear Parabolic

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Error

5 10 15 20 25 30 35 5 10 15 20 25 30 35 40 45

Percent Error (%) Inverse of Element Size (1/in)

Error Regression

Linear Parabolic

LINEAR Mesh Size (in) DOF Peak Stress (psi) % Error 0.2 4440 1354 32.3 0.1 16992 1705 14.75 0.05 66408 1919 4.05 0.025 262512 2006 0.3 PARABOLIC Mesh Size (in) DOF Peak Stress (psi) % Error 0.2 12936 1586 20.7 0.1 50316 1801 9.95 0.05 198024 1931 3.45 0.025 785016 2006 0.3

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Split Mesh

Split meshing is a technique of using two different mesh

densities in a single part

Used to keep element/node/DOF count low while increasing

accuracy where you need it

Most practical way to address stress concentrations in parts

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In Conclusion

Refining the mesh will converge the maximum stress values to the solution, kind
f obvious but this simple example compounds as models increase in

complexity.

Computation times may have only increased slightly in our example, but this

effect will be magnified in more complex models.

Using parabolic elements, while increasing run times, will converge on the same

answer much more quickly than just using linear elements, but can be situationally effective.

The best way to approach the balance between analysis run time and solution

accuracy will be to split mesh according to your geometry.

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STRUCTURES.AERO

Structural Design and Analysis (Structures.Aero)

Structural Analysis

Team of stress engineers that help our clients

design lightweight and load efficient structures.

We service aerospace companies and other

industries that require high level analysis.

Specialty in composites and lightweight

structures

Tools used include hand analysis, HyperSizer,

Femap, NX Nastran, Fibersim, NX, Solid Edge, Simcenter 3D, LS Dyna, and LMS.

Software Sales and Support

Value added reseller providing software, training,

and support for products we use on a daily basis.

Support Femap, NX Nastran, Simcenter 3D,

Fibersim, Solid Edge, and HyperSizer.

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For questions on the material covered today, please contact Andrew Nelson. For questions about pricing, or to see a demo, please contact Marty Sivic.

Questions?

Marty Sivic

Director of Sales msivic@structures.aero 724-382-5290

Andrew Nelson

Stress Engineer aNelson@structures.aero 703-935-2816