Learning Forum

[nicolicfs]

Hi,

There are times where I like to apply a small displacement to a part to pre-load it, then switch to a force for the final target load. To do this in APDL, you specify FORCE as the ramping key on DDELE in the second step. Is there anyway to do this directly in the Mechanical GUI (other than by using APDL command snippets)

Thanks,

Nicoli

[Govindan Nagappan]

You can right click on the tabular data and use "activate/deactivate at this step"


In the example shown above, I deactivated the force load at the second step. The force value will be greyed out and the graph will reflect this change
I checked the input file(ds.dat) and noticed that sfe command is used to apply the force load. sfedel was used for the second step
See if this is an option for you

[nicolicfs]

In the first step, I want to apply a displacement, then in the second step I want to apply a force. It seems that by default Mechanical will ramp the force from zero. However, I can workaround this with APDL commands. Compare reaction force in the first graph (this is the default behavior). In this case, I have applied a displacement in the first step, which brings the reaction force to just over 2000 N. Then, I deactivated the displacement and apply a force in step 2. You can extrapolate to see that the ramp for the force would start at 0 at time of 1 sec. What I want to happen is shown in the second image, where the force ramps from the value when the displacement is deactivated. This was achieved with an APDL command of DDELE,my_node,UY,,,FORCE
So, my question is, when I deactivate a displacement BC in Mechanical, is there a way to also control the ramping agrument?

[Govindan Nagappan]

Can you use a function load:
Example:

You can then deactivate loads at selected steps. This way loads should be ramped. See if it helps
Otherwise you may have to use APDL commands

[nicolicfs]

There is no way to pre-program the force in a table, because the force at the end of step 1 is unknown until the analysis starts.