1. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry: Common Complications for FEA Analysis  Discussion of common complications in finite element analysis (FEA)  Thin walled elements  Extreme aspect ratios, such as I-beams  Contact conditions that change during analysis

2. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry Common Complications with FEA Overview Section 1 Module 8 Page 1  Usually, geometry imported into FEA can be automatically meshed with the default mesh options with no issues.  Sometimes there are complications with meshing, especially when one dimension is extremely large compared to the other two.  Sometimes, small features also complicate a mesh and distort local elements.  In assemblies, objects sometimes move relative to each other and come into contact after analysis, also causing difficulties.

3. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry Common Complications with FEA Example Section 1 Module 8 Page 2  I-beams are an example of long, slender objects with small cross-sectional areas.  I-beams are both thin-walled elements and have high aspect ratios.  Autodesk® Simulation Multiphysics has a built-in utility to create beams from library databases.

4. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry Common Complications with FEA Defining beams within FEA Section 1 Module 8 Page 3  Beams can of course be modeled in CAD and imported into your FEA package, but it is difficult to refine the mesh enough to get a true output.  Alternatively, beams can be defined with Autodesk® Simulation Multiphysics, using line segments defined as beam elements and the software’s built-in beam databases.  These beams model with their cross sections and are highly accurate.  They also provide shear and moment diagrams for the user.

5. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry Common Complications with FEA Small features  For a small feature on a large object, it can be difficult to get the mesh density needed on the small feature. To resolve try:  Locally refining the mesh  Switching to tetrahedral elements, or a mixture of tetrahedrons and bricks  Suppressing small features in areas of low stress  Redesigning to eliminate or reduce the severity of the small feature Section 1 Module 8 Page 4

6. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry Common Complications with FEA Contact conditions that change during analysis  When an assembly has a large range of motion, such that two objects that are initially far apart come in contact, the analysis may fail. To resolve try:  Predefining a contact between the two objects, such as “Surface”  Limiting the range of motion with boundary conditions  Removing some components from the assembly and just importing the loading that would occur Section 1 Module 8 Page 5

7. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry Common Complications with FEA Thin-walled features  When an object has one dimension that can be described as its “thickness”, the user may have trouble meshing the geometry. To resolve try:  Using the midplane geometry to treat the geometry as surfaces, inputting the thickness as a parameter  Modeling as plate elements  Using CAD to model as surfaces Section 1 Module 8 Page 6 Solidworks® beam as plate and midplane

8. © 2011 Autodesk Freely licensed for use by educational institutions. Reuse and changes require a note indicating that content has been modified from the original, and must attribute source content to Autodesk. www.autodesk.com/edcommunity Education Community Working With Imported Geometry Common Complications with FEA Summary Section 1 Module 8 Page 7  Discussion of common complications in finite element analysis (FEA)  Thin walled elements  Extreme aspect ratios, such as I-beams  Contact conditions that change during analysis  The video will demonstrate modeling an I-beam in Autodesk® Simulation Multiphysics and discuss some of the common complications that can occur with finite element analysis.