Four-node membrane element (M3D4 and M3D4R)

These elements are similar to the S4 and S4R shell elements, respectively, except that they cannot sustain bending. This is obtained by modelling hinges in each of the nodes of the elements. Apart from that, all what is said about the S4 and S4R elements also applies here with one exception: instead of the *SHELL SECTION card the *MEMBRANE SECTION card has to be used.