Contents of pointer number 40 for 3d beams

[giovastabile]

Hi,

I'm working on Fluid Structure interaction with the coupling of OpenFoam with feap. I'm doing the coupling using the energy conservation geometrically exact beam element by SIMO. At runtime I need to exchange data between feap and the fluid solver. What I need is to have at each time step the nodal values of displacements and rotations. I understood that one has to use the pointer number 40 but I don't understand what is exactly stored in this array. For each node I have 3 displacements and 3 rotations. If I'm not wrong the displacements should be referred to the initial position of the beam and are not incremental values.

For rotations is more trivial. I guess they are also rotations referred to the initial configuration of the beam but in which way are they parameterized? What I get from pointer 40 is the rotation vector respect to the initial configuration? Or they are the three euler angles? In that case in which order is the rotation given? (since finite rotations do not commute)

I hope that I have been enough clear.

Thank You,

Giovanni.

[Prof. R.L. Taylor]

In finite beams the rotations are not stored in hr(np(40)).  Instead the information is in the pointer hr(82) -- this makes it hard to do what you want.  The parameters for the simo conserving element are stored as quaternions so you need to understand them and the form you need.