Engine Subroutine RUSERnn for Spring Elements
This subroutine calculates the internal forces and moment versus the velocity, old forces, moments, and user’s variables and parameters.
Arguments
C
SUBROUTINE RUSERnn(NEL ,IOUT ,IPROP ,UVAR ,NUVAR ,
2 FX ,FY ,FZ ,XMOM ,YMOM ,
3 ZMOM ,E ,OFF ,STIFM ,STIFR ,
4 VISCM ,VISCR ,MASS ,XINER ,DT ,
5 XL ,VX ,RY1 ,RZ1 ,RX ,
6 RY2 ,RZ2 ,FR_WAVE)
C
Definitions
Argument  Format  Description 

NEL  Integer read only scalar  Number of elements per group. In Radioss Engine subroutines, the element data are treated by groups for vectorization. This argument is machinedependent and set by Radioss. 
IOUT  Integer read only scalar  Output file unit (ROOTL00). 
IPROP  Integer read only scalar  Property number. 
UVAR  Float array read write  Array of size NEL*NUVAR containing user element variables. 
NUVAR  Integer read only scalar  Number of user element variables. 
FX  Float array read write  Array of size NEL containing an internal
local X force as input and a new force as output. Nodal X forces at nodes 1 and 2 in a local frame are defined as FX1 = FX and FX2 = FX. 
FY  Float array read write  Array of size NEL containing an internal
local Y force as input and a new force as output. Nodal X forces at nodes 1 and 2 in a local frame are defined as FY1 = FY and FY2 = FY. 
FZ  Float array read write  Array of size NEL containing an internal
local Z force as input and a new force as output. Nodal X forces at nodes 1 and 2 in a local frame are defined as FZ1 = FZ and FZ2 = FZ. 
XMOM  Float array read write  Array of size NEL containing an old
internal local X moment as input and a new moment as
output. Nodal X moments at nodes 1 and 2 in a local frame are defined as MX1 = MX and MX2 = MX. 
YMOM  Float array read write  Array of size NEL containing an old
internal local Y moment as input and a new moment as
output. Nodal Y moments at nodes 1 and 2 in a local frame are defined as MY1 = MY – 1/2*XL*FZ and MY2 = MY – 1/2*XL*FZ. 
ZMOM  Float array read write  Array of size NEL containing an old
internal local Z moment as input and a new moment as
output. Nodal Z moments at nodes 1 and 2 in a local frame are defined as MZ1 = MZ + 1/2*XL*FZ and MZ2 = MZ – 1/2*XL*FZ. 
EINT  Float array read only  Array of size NEL containing internal energy. 
OFF  Float array read write  Array of size NEL containing deleted
element flags.

STIFM  Float array write only  Array of size NEL containing element translational stiffness in time step computation. 
STIFR  Float array write only  Array of size NEL containing element rotational stiffness in time step computation. 
VISCM  Float array write only  Array of size NEL containing element translational viscosity in time step computation. 
VISCR  Float array write only  Array of size NEL containing element rotational viscosity in time step computation. 
MASS  Flat array write only  Array of size NEL containing element mass in time step computation. 
XINER  Float array write only  Array of size NEL containing element spherical inertia. 
DT  Float read only  Current time step 
XL  Float array read only  Array of size NEL containing element length 
VX  Float array read only  Array of size NEL containing X
velocity. Nodal velocities at nodes 1 and 2 in a local frame are defined as VX1 = VX/2 and VX2 = VX/2. 
RY1  Float array read only  Array of size NEL containing Y rotational velocity at node 1. 
RZ1  Float array read only  Array of size NEL containing Z rotational velocity at node 1. 
RX  Float array read only  Array of size NEL containing torsional
velocity. Nodal torsional velocities at nodes 1 and 2 in a local frame are defined as RX1 = RX/2 and RX2 = RX/2. 
RY2  Float array read only  Array of size NEL containing Y rotational velocity at node 2. 
RZ2  Float array read only  Array of size NEL containing Z rotational velocity at node 2. 
FR_WAVE  Float array read only  Array of size NEL not yet used. 