Two-dimensional Shape Functions

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with <math>\quad p=\frac{(n+1)(n+2)}{2}</math>
with: &nbsp; <math>\qquad p=\frac{(n+1)(n+2)}{2}</math> &nbsp; the number of terms.

Revision as of 09:49, 4 November 2009

Shape functions are selected to fit as exact as possible the Finite Element Solution. If this solution is a combination of polynomial functions of nth order, these functions should include a complete polynomial of equal order.

That is, a complete polynomial of nth order can be written as:

f(x,y)=\sum_{i=1}^p \alpha_i x^j y^k \qquad j+k \le n

with:   \qquad p=\frac{(n+1)(n+2)}{2}   the number of terms.

can only fit polynomial functions of pth order if they content a polynomial function

for any polynomial function of pth order it is enough to use p-1 integration points.


  1. Pascal's triangle
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