Spring 2008, MET 415 - FEA
Applications I
Prof. Dave Johnson, dhj1@psu.edu, Penn State - Erie, The Behrend College
Debriefing: Plate
with a Hole - In-class Example
A 12" x 12" x 1" aluminum plate has a
1" diameter hole at the center. This plate experiences a tensile (distributed)
load of 1000 psi in the horizontal direction. This model exhibits two planes of
symmetry. Determine the stress near the hole. Determine the deflection of
the plate.
CONCEPTS:
2D modeling
Planes of Symmetry
Stress Concentration
Geometric Construction: Primitive Shapes, Boolean
Operations
Finite Element Meshing / Mesh Controls
Presenting and Interpreting FEA Results
WHAT ELSE DID WE LEARN ?
- Choice of ELEMENT TYPE:
- Utility Menu: Help -> Table of Contents -> Elements Manual
- Look up PLANE82, PLANE183, PLANE42 and PLANE182 (in Chapter 4)
- Why can we use a two-dimensional model of this plate ?
Location of ANSYS Material Library:
- Z:\Labsoft\Ansys\Ansys11\Ansys11\v110\ANSYS\matlib
What gives this model "symmetry" ?
What is a Symmetry Boundary Condition ?
- Symmetry is (Important or NOT Important) on such a simple model.
- We use symmetry because ________________________
Picking in ANSYS
- Right mouse toggles Pick/UnPick mode
- Left click-hold-move mouse, allows you to preview the pick
- If the PickTool does not appear when it should (Windows bug), "Reset
Picking"
Order of Picking Entities may be critical (in subtraction) !
Geometry of AREAS includes LINES and KEYPOINTS
- What is the difference between "OK" and "APPLY" ?
- DELETE "AREAS AND BELOW" to completely remove unwanted geometry
(UNDO) SAVE and RESUME of the ANSYS database file
Clear the mesh, change mesh controls, and mesh again.
Solid Model Loads vs. Finite Element Model Loads
What is LS (when you Solve Current LS) ?
Postprocessing:
- Does the deformed shape make sense ?
- Can deformation occur ACROSS the symmetry plane ?
- Can deformation occur ALONG the symmetry plane ?
- What should the SF values be ?
- Do the values and the sign on the normal stress, SX (or sx) make sense ?
- What is a reasonable target for SEPC (stress error energy percentage) ?
- SEPC measures error from ____________________
- If you want to reduce the SEPC, which elements should you refine, i.e., make smaller ?
- What is SMNB and SMXB in the legend of the SX contour plot ?
- What is the difference between a contour plot of Nodal Soln. and Element Soln. ?
- What effect does PowerGraphics have on your plots ?