- [Instructor] Now, we're going to open up
the SolidWorks file and that file is tray three begin.
Now, if you don't have SolidWorks 2018 or later,
then you can use the parasolid file, which is shown here.
Now, we click on the simulation tab
and we're going to be copying the existing study.
Now, we're going to set up a linear dynamic analysis
and particular type, scroll down,
is going to be a harmonic analysis,
in other words, a frequency response.
We'll give the newest study a name,
frequency response tray three.
And then we'll click okay.
Now, I want to set up some analysis control parameters,
so we come down to properties and we're going to choose
a number of frequencies to run with is six.
I'm going to change this to cycles per second or hertz.
It's a standard little tramp to leave it
in radians per second.
Now, I want the analysis to range from zero hertz,
and I'm gonna set up an upper value of 1000 hertz.
We go to the advanced options, and I'm going to increase
the number of points per natural frequency to 20,
and the spread is gonna be to .6.
Going to change the interpolation to linear.
Let's just review the mesh, so click show mesh.
And now I'm going to define the external loading.
It's gonna be uniform basic citation.
We're going to use acceleration.
I'm going to have the acceleration normal
to the surface I'm selecting here,
so just pick any of these surfaces,
and then we set up the acceleration in G,
choose the normal direction, have one G.
I can reverse the direction and I want to set up
the curve that I'm going to be using.
Click edit.
The first data point is one hertz .001 G.
Next one is 160 hertz.
We stay at .001 G.
Then there's a ramp up, 400 hertz, we see one G.
There's then a plateau, 650 hertz, we see one G.
And then there's a tail off, so at 1000 hertz,
we see .001 G, and if I click back into the spreadsheet,
you can see the form of the loading
and the little inset above.
If I click on view, then we can see a bigger view of that.
So the plateau exists between 400 and 650 hertz,
so that completes the setup, so we just check okay.
Again, check okay.
Now, we right mouse click to define the damping,
and we want to set up all the damping
to be .02, two percent damping.
So again, just check okay.
Now, we go to result options,
right mouse click, edit, define,
and I can switch off the stress components.
The option to select modes isn't available at the moment.
The implication of this is that the model database
hasn't been created, we haven't run the normal
modes analysis yet in this study,
so I'm going to rerun the normal modes now.
So, we go to the run this study icon
and in the dropdown there we choose run frequency.
This will only run the normal modes analysis.
Now again, I've accelerated the timeline
and so, we can go straight to the results.
There are 10 natural frequencies,
so we could review the 10 mode shapes if we wanted to.
Now, if we go to result options, edit, define,
now we can see that we can select modes.
If we edit there, you find that the six modes
that we said we would be using
can be deselected or selected.
So again, we could do a model filtering approach
if we wanted to do that.
So we're all ready to run the frequency response analysis,
so we go to run this study and click on run the study,
and the first thing we get is an error message coming up.
The error message is telling us
that the excitation range in our loading curve
doesn't match the range of frequencies
that we specified in our analysis setup,
and specifically, there's something missing
at the bottom end of the range.
Now, this is a very common error,
so I thought I would highlight it here.
So let's check the basic citation.
So we edit the definition and we then edit the field,
and in fact, what we notice that we used
radians per second instead of hertz,
so let's correct that and then I'm going to
input the data I did before, but in terms of
hertz, not radians per second.
So if I fast forwarded the timeline
to complete the data there, we've corrected the data,
so let's now rerun the frequency response analysis.
I run the study, and again, we find we have an error.
It's the same message as before,
so we obviously didn't correct the fundamental problem
where the bottom end of the frequency range we define
doesn't match the frequency range of the loading we specify.
So let's have a look at the base excitation again.
Edit the definition.
Let's open up the curve.
Now, the error here is that we said
we're gonna start at zero and we actually started
at one in the loading, so there's a mismatch there.
So the analysis definition is from zero to 1000 hertz
and the loading also has to be from zero to 1000 hertz.
Now, let's see if that works out,
so we go to run the study, launch the frequency response,
and in fact, this time it is running.
Again, I'm accelerating the timeline
so we can get straight to the results.
So the first thing we want to do is to have a response plot,
so we define a response graph.
We're going to use remote location mode,
which is at the center of the payload mass we defined.
Now, we need to define this as an acceleration,
acceleration in the zed direction,
and we want the units to be NG, so check okay.
And now we see the response graph.
I want to change some of the default options.
We're going to change the scale
so that it fits more neatly between the range,
which is up to 1000, and we're going to change the symbol
to be a diamond symbol.
So let's expand the graph and took a look
at the response of the payload mass
as an acceleration across the range.
Now, we see the first mode 191 hertz,
mode two is 261 hertz, and then heading towards
the plateau region, we've got mode three at 498.
Right in the plateau region, we have mode four 662 hertz
and then, edging out of it, rolling off,
we've got mode five 801 hertz and mode six
has almost no response at 869 hertz.
Now, we're going to define a second response plot,
and this time, we're going to pick specific nodes.
So we're going to pick nodes at the corners
and the center line, and we can arrange these neatly
to take a screenshot record of these positions.
Now, we need to define acceleration and in the zed direction
and we need to change the units to be in a G,
and then check okay.
So here's response graph and I just want to
change some of the properties from the default.
Click the axis and then set up the symbols
so we can see clearly the different response curves.
Can see from the response graph that there are
two nodes which are peaking at mode four,
which is 662 hertz.
These are a node at the corner
and the node on the center line.
Now, this gives us a great clue
that we should be checking out the
acceleration contour plot in this frequency range.
So let's go and set up that acceleration contour plot.
It's going to be an acceleration plot
and we're going to plot acceleration
in the vertical sense in G units.
We change the settings to be discreet, we check okay.
But at the moment, we're looking at
the response to 1000 hertz, but we want to
edit the definition and pin this result
so now we can move around the frequency range.
The first stop is 498 hertz, which is mode three,
whether it's some response being shown here.
Now, we move up to mode four, which is 662 hertz
where the peak responses are found.
This is the peak response we spotted at the corner node
with the center line node fairly close behind.
The other corner node is showing very little response,
and the payload mass center gravity again,
showing very little response.
The final thing I want to do is to
set up an animation of this so we can see
the acceleration response of the whole structure
throughout the range.
So right mouse click on acceleration and choose animate.
Now, I have very little memory available
to buffer the animation frames,
so I've clipped the animation range
from 200 hertz to 800 hertz.
I've also go a sampling rate of factor of two.
Now, that gives me 38 frames, which fits in memory okay,
so if you keep an eye on that and adjust
to get that value to something which your memory can handle,
then that's the key.
So if we watch the animation now,
we can see very little response.
We're climbing 250 hertz, coming up towards 300,
400 hertz, and now we're starting to get into
the responsive region, 500 hertz,
580 hertz, and now we get towards that key mode,
which was mode four, the 662 hertz,
and now we're coming to the tail out,
there's very little response in there.
Now, we'll play it a couple more times.
Runs through to the end there, and one more time.
And we'll stop there.
So in this video, we've seen a user defined load curve
and how that can be tricky to set up, we've seen
a frequency response craft to investigate the peaks,
and then a subsequent contour plot
to investigate the overall response,
and then finally, animating through frequency.
So let's save the file now and we're going to save it as
tray three frequency response end.
And we do want to save the results files.