I am presently developing a VUEL in abaqus. I have some problems defining RHS for a 3-D brick element (C3D8). As per the abaqus documentation,
RHS gives the element internal force vector; for a simple one dimensional truss problem, The RHS is as follows (I am quoting from the subroutine reference manual example):
c assemble internal load in RHS
rhs(kblock,1) = -forceTra
rhs(kblock,4) = forceTra
The above is for a single truss element , where forceTra = k*(u2-u1) and -forceTra = k*(u1-u2).
However, I cound not find out what will be the form of RHS vector for a full 3-D brick element (C3D8 for full integration or C3D8R for a single intergation point). I would be eagerly awaiting for somebody to help.