Ansys Class

Preprocessing
Input file

Every degree of freedom represents an equation to be solved

Global coordinates vs Element coordinates

Remember we are solving for DISPLACEMENTS

Displacement to Strain
Displacement to Stress

Element Stiffness Matrix

Element Formulation Illustration

Wave front minimizers
Band width minimizers
so the stiffness matix is a diagonal as possible

Convergence

• Analysis will converge relative to the accuracy of the PC
• Hermite Functions
• The different element (types) formulations must be compatible

Wheels and Tires... watch out for load assumptions!

Audit of the Answer - Does the answer make sense?

Element Shapes & Meshing - (review "Common Mistakes")

Transformation of Stess

Principal Stess - Planes where there no shear stresses

Eigenvalue

Eigenvalues are a special set of scalars associated with a linear system of equations (i.e., a matrix equation) that are sometimes also known as characteristic roots, proper values, or latent roots (Marcus and Minc 1988, p. 144).

The determination of the eigenvalues and eigenvectors of a system is extremely important in physics and engineering, where it is equivalent to matrix diagonalization and arises in such common applications as stability analysis, the physics of rotating bodies, and small oscillations of vibrating systems, to name only a few. Each eigenvalue is paired with a corresponding so-called eigenvector (or, in general, a corresponding right eigenvector and a corresponding left eigenvector; there is no analogous distinction between left and right for eigenvalues).

Failure Theories

Von Mises & Cressa Criteria - Ductile Material
cylinder skued equally in three dimensions, if its surface is projected onto any of the three planes, it would form an ellipse. Try modeling this to prove it to yourself.

Coulomb-Mohr Criteria - Brittle Material

Stess Categories

**** Ductile material "shakedown" *****

Open Source FEA programs....
http://www.openchannelfoundation.org/discipline/Finite_Element_Analysis/