Contrib:KeesWouters/dynamicload

Dynamic analysis of an axial loaded cylinder

[under construction .... not finished yet ...]

To start with, this contribution mainly focuses on the use of Salome and Code Aster, not on the results and the mechanical justifications of the code that has been used. So no guarantee that the results will be correct up to the fifth decimal place, which they are not. I do hope though that this information is useful. For me it has been, because I had to think about some commands and look through the documentation and learn from that. In case of mistakes, errors or remarks, please notify me, or better, you are invited to correct or edit them yourself. Enjoy.

[As usual, the files that define the geometry, mesh and command files can be found at the end of this contribution.]

Geometry of the construction

The geometry is based on this contribution: [[]]. Only the mesh is much coarser to limit calculation time.

Boundary condition and load

Also the boundary conditions are the same as [here], as is the load. The load is an axial force on the top edge of the cylinder. A scaling factor is applied by the MULT_FONCT command in the []. This scaling factor is zero for the first 100 ms, and goes to unity within a very small time scale, ie. small compared to the resonance frequencies of the axial modes of the cylinder. The scale factor remains unity until the end of the calculation at 300 ms.

Detailed commands of the applied load

The AFFE_CHAR_MECA defines the boundary conditions at the bottom of the cylinder: all dofs are restricted. At the top an axial force is applied with a total force of 5500 N, devided over the circumference of the cylinder.

# define BC and loads
# geometry of cylinder for applying loads
th    = 0.10        # [mm] thickness of shell 
dcyl  = 4.00        # [mm] diameter of cylinder
pie   = math.pi     
Lcyl  = pie*dcyl    # [mm] circumference of the cylinder
Fax   = 5500.0      # [N]  total axial force

clamp=AFFE_CHAR_MECA(MODELE=modelc,
                      DDL_IMPO=(_F(GROUP_MA=('Cbot'),
                                  DX=0.0,
                                  DY=0.0,
                                  DZ=0.0,
                                  DRX=0.0,
                                  DRY=0.0,
                                  DRZ=0.0,),
                                 _F(GROUP_MA=('Ctop'),
                                  DX=0.0,
                                  DY=0.0,
                                  DRX=0.0,
                                  DRY=0.0,
                                  DRZ=0.0,),),
                      FORCE_ARETE=_F(GROUP_MA='Ctop',FZ=+Fax/Lcyl,),);

......

A time step is defined by the DEFI_LIST_REEL command. The scaling function castle is defined by the DEFI_FONCTION command. In total tsteps (200) output times will be generated.

# The load will be applied in steps defined by a 'time' function and
# multiplification factor on the load.
tsteps = 200
to     = 0.000
tc     = 0.005
t1     = (1+1e-5)*tc
te     = 0.020
time=DEFI_LIST_REEL(DEBUT=0.0,
                  INTERVALLE=_F(JUSQU_A=te,NOMBRE=tsteps,),
                  INFO=2,TITRE='time',);

castle=DEFI_FONCTION(NOM_PARA='INST',
                 VALE=(to,  0.00,
                       tc,  0.00,
                       t1 , 1.00,
                       te,  1.00,),
                 INFO=2,TITRE='castle',);