Creating the Abaqus/Explicit forming analysis
Copy the Standard
model to a model named
Explicit
. Make all subsequent model changes to
the Explicit
model. To begin, edit the
Steel
material definition to include a mass
density of 7800 kg/m3.
A concentrated force will be applied to the blank holder. To compute the
dynamic response of the holder, a point mass must be assigned to its rigid body
reference point. The actual mass of the holder is not important; what is
important is that the mass should be of the same order of magnitude as the mass
of the blank (0.78 kg) to minimize noise in the contact calculations. Choose a
point mass value of 0.1 kg. To assign the mass, expand Engineering
Features underneath the Holder in the
Parts container in the
Model Tree.
In the list that appears, double-click Inertias. In the
Create Inertia dialog box that appears, enter the name
PointMass
and click
. Select the reference point of the holder, and
assign it a mass of 0.1
kg.
For the first attempt of this metal forming analysis, you will use tabular
amplitude curves with the default smoothing parameter for both the application
of the holder force and the punch stroke. Create a tabular amplitude curve for
application of the holder force named Ramp1
using the data in
Table 1.
Define a second tabular amplitude curve for the punch stroke named
Ramp2
using the data in
Table 2.
Time (sec) | Amplitude |
---|---|
0.0 | 0.0 |
0.0001 | 1.0 |
Time (sec) | Amplitude |
---|---|
0.0 | 0.0 |
0.007 | 1.0 |
As with the
Abaqus/Standard
analysis, you will need two steps for the
Abaqus/Explicit
analysis. In the first step the holder force is applied; in the second step the
punch stroke is applied. Delete the step named Move
punch
. Replace the step named Holder
force
with an explicit dynamics step, and specify a time
period of 0.0001
s. This time period is
appropriate for the application of the holder force because it is long enough
to avoid dynamic effects but short enough to prevent a significant impact on
the run time for the job. Enter Apply holder
force
as the step description. Create a second explicit
dynamics step named Move punch
with a time
period of 0.007
s. Enter Apply
punch stroke
as the step description.
To help determine how closely the analysis approximates the quasi-static assumption, the various energy histories will be useful. Especially useful is comparing the kinetic energy to the internal strain energy. The energy history is written to the output database file by default. Modify the history output request for the punch reference node to request output at 200 evenly spaced intervals.
Open the Load Manager, and modify the concentrated
force named RefHolderForce
in the step named
Holder force
so that the amplitude definition
for this load is set to Ramp1
.
Change the displacement boundary condition
RefPunchBC
in the Move
punch
step so that U2 is set to –0.03 m
in the step. Use the amplitude curve Ramp2
for
this boundary condition.