- [Instructor] In this video, we're going to investigate
the difference in the setup of models
which incorporate trusses, which we've just been covering,
and those which include beam elements.
We're going to look at the differences in the approach,
and the requirements of those two types of elements.
Now if you got SolidWorks version 2018 or later,
we go to the exercise folder, and open the SolidWorks file,
taper_and_constant SolidWorks part.
If you're working with a SolidWorks version prior to 2018
or don't have this SolidWorks file available,
then choose all files in the dropdown
to enable you to see all the file types,
and choose the Parasolid instead.
So we're going to open up the SolidWorks part,
and we can see that there are three solid bodies present.
If we look at them, they are Loft1, Loft2, and Loft3.
They're just being created by lofting
between simple sketches.
Now some of the characteristics we're interested in,
Loft1 tapers from front to back.
Loft2 is a constant cross section, but it is a short length.
Loft3 is a constant cross section, but it's quite long.
So with that in mind, let's create a new study,
let's name it beam and truss,
because we're gonna be creating
both types of elements this time.
We want to do a static analysis, and we check okay.
Now let's open up the part folder,
right mouse click on Loft1, which is SolidBody 3,
but we want the definition Loft1.
We can see it's the tapered end section here.
Click on treat as beam.
Again if we right mouse click and say edit the definition,
notice we can't pick it as a truss.
That radio button is now grayed out.
We can only create a beam, because it's a tapered section
or a non-constant section.
Wouldn't make any sense to use this as a truss.
Notice End1 and End2, the red and the blue blob there.
So we check okay.
Now we go to Loft2, right mouse click,
and say treat as beam.
Now notice we get a warning.
The body is too short to be considered as a beam.
The warning message is indicating the beam is too short,
and it violates slender beam theory.
The beam length to depth ratio is less than 10.
There's a little bit of a quirk here,
because although Loft1 is shorter than Loft2,
it didn't trigger the warning.
So right mouse click again on Loft2,
again edit the definition.
This time we can pick either the beam or the truss option,
what kind of element we want to convert it into.
A truss would be perfectly acceptable obviously
as a constant cross section.
So we'll leave it as a beam.
Now, we have the option to choose section properties.
What's happening here is that we can override
the default torsional constant
and the position for maximum shear stress,
and also the shear factors
in the two directions, one and two.
We can also control for beam,
the way that the ends are connected.
So, at the red end, which is End1,
we'll say it's rigidly connected to the adjacent beam,
and then two, it's also rigidly connected.
And we can change that to hinge,
slide, or a manual definition
of the way that the beam is constrained.
Let's right mouse click on SolidBody 2, which is Loft3.
If we say treat as beam, notice the warning doesn't come up
because the length to depth ratio of this solid body
is bigger than 10 to one.
Let's go back and reset Loft2, edit the definition,
and let's set that as a truss.
Now just out of interest, let's mesh this.
So create mesh.
Now we can see the difference in approach.
The truss section can only have one element.
There's just one element which will carry axial load
down the length from that joint to that joint.
We got a default number of elements.
It's a beam section, or a beam geometry,
and it's been meshed with beam elements.
Again, for this section here, Loft3,
between that joint and that joint,
we've actually got this number of elements created.
So, the beam section is spawning beam elements.
The truss section is spawning just one truss per section.
In fact if we look at Loft1, which is the tapering set,
and edit the definition, one thing of interest here
is that we can't change the section properties.
Because each one of those elements
has a different section property as it tapers down,
it's not possible to change them on mass.
So just a warning there in that particular case.
Now the result of our little exercise here
isn't a valid FEA model, but it's really served the purpose
of demonstrating the differences
between the truss and the beam setup.
Now we can save the file, we can save it
as taper_and_constant_end.
So in conclusion, in this video,
we've explored the differences
between with set of the beam and the truss elements,
both using geometry starting points.
We've also seen some of the different qualities
that the truss and the beam elements will exhibit.