- [Instructor] In the previous video, we saw that
the structure made up of beams
seemed to be behaving in a truss-like manner.
Let's just now double-check that.
So right-mouse-click on Results
and choose Define Beam Diagrams.
We can check the pin here.
At the moment, we're looking at Sheer Force
in direction one, if you look at the axial force, check okay
We need to make sure we're set to pound force.
We can see, again, the correct values, 1831 and 13940.
They're actually plotted at an angle or in a plane
to those beam elements, so it's axial load only.
So that looks fine. Now with the pin down, we can change
the type of beam diagram we're going to look at.
So I want to change this to moment about direction one.
Check OK. Pound force inches. Check OK.
Now there's some values appear
as if there is a bending moment distribution,
but the order of nine e to the three is the maximum,
so they're small spurious values due to rounding errors.
Let's do the same for moment two.
Check OK. Again we can see e to the minus nine,
so again, small spurious values,
so everything checks out okay.
Let's unpin and close that down.
See we've been spawning plots, down as we go.
Come back to displacement plot.
I want to move away from the benchmark,
and change the configuration now to beam arrangement,
which is fully welded at the top mode, just here.
We're still pinned at the two base points, here and here.
So we're gonna go to solid body one,
and I'm going to edit this to change the end connection.
So edit the definition. Whereas before, End1 was hinged,
now we're going to check that to be a rigid connection,
so it's gonna transfer bending moment around the corner now.
Check OK. We do the complementary job for solid body two.
Edit that definition. So again, we click that to be rigid.
Check OK. Now we've changed the model, so we need to rerun.
Now if we look at the deflections,
they're virtually identical to before,
where this was pin-jointed, but now
there's a slight curvature we can see.
We're going to double-click on moment about direction one.
This is the correct bending sense in plane.
Now we can see there's a small moment
being transmitted through, if we rotate this around,
we can see the moment's building up on the first leg,
and then falling off down the second leg,
so there's a moment of 67.75 pound force inches
being transmitted around this joint.
Now we can change this again and we can fully build in,
so we'll be transmitting moment
out of the constrained points down here.
So we change the model by going to fixtures.
The stud will be immovable. Go into edit the definition.
We want three translations, the three rotations fixed,
so we check OK, let's run the study.
Again we're looking at disbursements and stresses,
so let's just look at the disbursement part here,
let's look at it from the front plane.
Again we can see more bending type behavior.
What's interesting here is you can start to see
that the beams are really struggling a little bit.
We can see it's not a very continuous curvature here.
That's the first little bit of a clue
that we need to increase the mesh fidelity,
so let's go to the mesh control,
change the control here, edit the definition,
and let's up this, see what a fine
mesh control will give us. That gives us
twenty elements along there, so we check OK,
and now we need to rerun, and now we can see
the result has come out as much more
of a sophisticated curvature there.
Let's plot displacements. Now we want
to go to the bending moment about direction one,
so let's double-click on that.
And we have to rotate the system, so we see it.
Now you can see again a moment transmitted
around the joint here, but now
moment's taken now to the base,
as opposed to a truss like structure,
where the truss elements are only carrying n load.
Now we can check those reactions.
If we right mouse click on results,
and go to list result forces, which is effectively
our reactions, and we choose this joint,
registered and connected to the ground,
and this joint connected to the ground.
Now if we click update, you see the reaction forces
in x, y, and z, and we also see the resultant.
Let's close that down. OK let's now save the model.
And we'll save this as layout truss end.
So in conclusion, in this video we've seen
how to create the beam elements from weldments,
and we've also compared the response
of the beam element and the truss element.
We've gone through the stages of building this jointing,
and then we built in these joints to ground as well.