Dear Prof. R. L. Taylor
Thanks for your reply.
I am converting the subroutine framf3d.f into C/C++ and I‘m closing to finish this work. But there are some details unclear to me. For example, the meanings "ndfo(1)", "shflg" and "frotas" in the file framf3d.f, which are used when forming the lumped or consitent mass matrix.
According to the Reference: A. Ibrahimbegovic and M. Al Mikdad, IJNME, [1998],Vol. 41, pp. 781-814, the first order derivative of theta with respect to time is not the angular velocity. So for the beam model in framf3d.f, what's meaning of ul(4:5,,4)? They are the time derivative of theta, or the angular velocity? Or for the subroutine extrfb, it return the array v1,Spatial rotaional velocity at t_n+1, this v1 is the time derivative of theta, or the angular velocity?
Best regards.
Prof. Wei Yongtao
Sichuan Universtiy.