[Wikiversity-l] About finite elements method

[Marco Siracusano]

Referring to Wikiversity's tutorial "Introduction to finite elements/Axial bar finite element solution" I'd like to know why, on calculation of matrix Kij, the element K33 is equal to 1/h3 (and so, taking all the elements equal to 1/h, K33=1) and afterwards, when the matrix Kij is written in numeric form, K33=2. Really, taking K33=1 det(K)=0 and when K33=2 det(K)=1. I think that the value of the the element K33 has been modified taking into account boundary conditions. Otherwise?
Thanks for your answers.
Marco Siracusano
marco.siracusano at fastwebnet.it
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