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An accurate CAD model ensures accurate FEA analysis. FEA has no understanding of geometry. What FEA understands is nodes and elements created by discretizing the geometry. Geometry essentially acts as a template for mesh. If geometry does not allow elements/nodes to be generated at a certain location; there is a slim chance of getting decent results. Factors that contribute towards successful simulation are geometry, material properties, boundary conditions; last but not the least mesh generated.
The success of any design project resides in the ability of designer to quickly assess performance of design, evaluate design changes, optimize design cost, communicate information with other designers. This in essence boils down to effective communication between model geometry and mesh generated.
Choosing the right idealization will provide flexibility to make design changes, improve accuracy and speed. There are three types of elements available in COSMOS.
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Shell Mesh |
Solid Mesh |
Beam Mesh |
Shell Mesh
Shells are essentially 3 D surface representation of 3 D solids. Nature of geometry decides the type of element to be used. Sheet metal structures is best suited for shell mesh. Shell mesh gives accurate results with moderate amount of detail and renders itself to make changes easily. Analytical surface should be mid surface of actual geometry. Care should be taken to avoid mesh discontinuity due to gap in mid surfaces.
Shell modeling
To analyze geometry using shell mesh it is advisable to compress solids as mid surfaces. This can be done in solid works and COSMOS. Use mid surface option while meshing solids. Also, surfaces can be built from outer surface of solids using the surface feature.
Beam Mesh
Beam elements are generically used for meshing structural members. Ideal for calculating axial, bending, shear and torsional loads in structural members. They are very efficient to capture geometry with very little detail. Very accurate for long wireframes / extrusions.
Structural Member
Beam Mesh on Structural Member
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