4 nodes element

I'm an engineering student and i try to build my own shell element on matlab and trying to make the stiffness matrix through the shape function and the virtual wok principle.

after coding i compared the result obtained with matlab with a single sheel made in hypermesh and result are in the the same order of magnitude but different.

does anyone know which shape function or which mathematical model Hypermesh use for this type of elements?

I attached my matlab file.

thanks in advice.

 

Unable to find an attachment - read this blog