Begin by creating a dependent instance of the floor (double-click
Instances underneath the Assembly
container).
The circuit board will be dropped at an angle; the final model assembly is
shown in
Figure 1.
Figure 1. Complete circuit board assembly.
You will use the positioning tools in the
Assembly module
to position the packaging first; then you will position the board relative to
the packaging. Finally, you will create a reference point at each datum point
location of the board to represent the chips.
Position the packaging
From the main menu bar of the
Assembly module,
select
ToolsDatum
to create additional datum points that will help you position the packaging.
Select Point as the type, and select
Enter coordinates as the method.
Create two datum points at (0, 0,
0) and (0.5, 0.707, 0.25).
Click the auto-fit tool to see both points in the viewport.
In the Create Datum dialog box, select
Axis as the type and 2 points as the
method. Create a datum axis defined by the two datum points created in the
previous step, selecting the point at (0.5, 0.707, 0.25) as the first point in
the datum axis definition.
Tip:
Use the Selection toolbar to
restrict your selection to Datums.
Instance the packaging.
Constrain the packaging so that the bottom edge aligns with the datum
axis.
From the main menu bar, select
ConstraintEdge to
Edge.
Select the edge of the packaging shown in
Figure 2
as a straight edge of the movable instance.
Tip:
To obtain a better view of the model, select
ViewSpecify
from the main menu bar and select Viewpoint as the method;
enter (−1, −1, 1) for the viewpoint vector and
(0, 0, 1) for the up vector.
Figure 2. Select a straight edge on the movable instance.
Select the datum axis as the fixed instance.
If necessary, click Flip in the prompt area
to reverse the direction of the arrow on the packaging; click
OK when the arrows point in opposite directions as shown
in
Figure 2.
Tip:
You may need to zoom out and rotate the model to see
the arrow on the datum axis. The direction of this arrow depends on how you
defined the axis initially; if the arrow on your axis points in the reverse
direction of the one shown in the figure, the arrow on your packaging should
also be opposite to the figure.
Abaqus/CAE
positions the packaging as shown in
Figure 3.
Figure 3. Position 1: Constrain the bottom edge of the packaging to
lie along the datum axis.
Note:
Abaqus/CAE
stores position constraints as features of the assembly; if you make a mistake
while positioning the assembly, you can delete the position constraints. Simply
click mouse button 3 on the constraint you wish to delete in the list of
Position Constraints items found underneath the
Assembly container in the
Model Tree,
and select Delete from the menu that appears.
Create a third datum point at (−0.5, 0.707,
−0.5), and click the auto-fit tool again.
In the Create Datum dialog box, select
Plane as the type and Line and point
as the method. Create a datum plane defined by the datum axis created earlier
and the datum point created in the previous step.
Constrain the packaging so that the bottom face lies on the datum
plane.
From the main menu bar, select
ConstraintFace to
Face.
Select the face of the packaging shown in
Figure 4
as a face of the movable instance.
Figure 4. Select a face on the movable instance.
Select the datum plane as the fixed instance.
If necessary, click Flip in the prompt
area; click OK when both arrows point in the same
direction.
Accept the default distance of
0.0 from the fixed plane.
Finally, constrain the packaging to contact the floor at its center.
From the main menu bar, select
ConstraintCoincident
Point.
Select the lowest vertex of the packaging as a point on the
movable instance, and select the reference point on the floor as a point on the
fixed instance.
Abaqus/CAE
positions the packaging as shown in
Figure 5.
Figure 5. Final position of the packaging relative to the
floor.
Now, translate the floor slightly downward to ensure that there is no
initial overclosure between the packaging and the floor.
Convert the relative position constraints to absolute constraints
to avoid conflicts. From the main menu bar, select
InstanceConvert
Constraints. Select the packaging in the viewport,
and click Done in the prompt area.
From the main menu bar, select
InstanceTranslate.
Select the floor in the viewport.
Enter (0.0, 0.0, 0.0) as the start
point for the translation vector and (0.0, 0.0,
−0.0001) as the end point for the translation vector.
Click OK to accept the new position.
Position the circuit board
Instance the circuit board. In the Create
Instance dialog box, toggle on Auto-offset from other
instances.
From the main menu bar, select
ConstraintParallel
Face. Select the face of the board as a face on the
movable instance; select a face on the long side of the packaging as a face on
the fixed instance. If necessary, click Flip in the
prompt area to ensure that the arrows on both faces point in the directions
shown in
Figure 6;
click OK to complete the constraint.
Figure 6. Parallel face constraint for the circuit board.
From the main menu bar, select
ConstraintParallel
Edge. Select the top edge of the board as an edge on
the movable instance. Select an edge along the length of the packaging as an
edge on the fixed instance. If necessary, click Flip in
the prompt area to ensure that the arrows point as shown in
Figure 7;
click OK to complete the constraint.
Figure 7. Parallel edge constraint for the circuit board.
From the main menu bar, select
ConstraintCoincident
Point. Select the midpoint of the bottom of the
board as a point on the movable instance. Select the datum point at the center
of the cut in the packaging as a point on the fixed instance.
Tip:
Use the Selection toolbar to
restrict your selection to Datums.
Figure 8
shows the final position of the circuit board. The circuit board and the slot
in the packaging are the same thickness (2 mm) so there is a snug fit between
the two bodies.
Figure 8. Final position of the circuit board.
Create the chips
Create a reference point at each of the three datum point locations on
the board to represent each chip. Each of these reference points will later be
assigned mass properties. To create a reference point, select
ToolsReference
Point from the main menu bar of the
Assembly module.
Once you have created the reference points, the assembly is complete.
Before continuing, create the following geometry sets that you will
use to specify output requests and mass properties:
TopChip for the reference point of
the top chip
MidChip for the reference point of
the middle chip
BotChip for the reference point of
the bottom chip
