This functional is the one to be minimized using the Rayleigh-Ritz procedure.
As for what basis functions to use, the simplest choice is a set which permits the displacement field over the element to be a general linear function of \(x\) and \(y\). For this, three basis functions are needed.
There are two ways of formulating them,
one based on Cartesian coördinates and the other on so-called
‘natural’ coördinates. The ultimate result is the same,
but in some circumstances one of the two formulations may be superior.
R. Funnell Last modified: 2018-11-07 12:52:06
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