MSC Nastran; Patran Tutorial - Direct Frequency Response; Eccentric Rotating Mass with Damping Video Lecture | Nastran: Basic Tutorial for Students - Design Softwares

in this video I'll be performing your
frequency response analysis using the
direct method it was this spring-mass
system shown here full details of this
exercise are on page 429 or the PDF
linked in the video description below
now I'll go ahead and strain your patrin
session and before I begin there's the
requirement that you have to have this
dot CSV file
it's called loading CSV and I'll include
a link in the video description below
let me pull a patch on again I'll start
a new patch on database call that
problem 23 and I'll start by hitting OK
here and I'll build a model from scratch
so I'll bills my notes manually in my
elements the same way here click node
edit and we'll define four nodes
negative 1 1 0 another one at 0 0 0 0 1
0 and another one at 1 1 0 hit apply and
the notes have been created here at the
bottom I'm told they've been created if
I go to home and click node size you can
see them here another way is if you go
to label control and turn out the node
numbers you see one two three and four
next I'm going to link the nodes with
the beam element so go to the meshing
tab go to element edit change the shapes
up bar and simply connect the dots so
all in that 1 2 then 1 to 3 3 to 4 2 to
4 and 2 to 3 I'll turn on the element
numbers so I see 1 2 3 4 and 5
next I'll define
my properties you know under tools I'll
clog beam library I'll call this cross
section cross section I'll scroll till
the right until I find the rectangular
section and the units for this exercise
are inches pounds and PSI the width of
the cross section is 1 inch and H or the
height is 1 inch if you can hit OK or
apply on the bottom and make sure it
says beam beam section cross section
created I'll define my material so under
isotropic I'll call this one mat for
input properties I'll give it a young
modulus of three e9 and a sine value of
0.3 a density at point one two five
they'll hit OK it applies to create the
material next I want to apply this
material and the cross section to these
top elements under windy properties
click the beam icon call this beam
section the beam member under input
properties for section name select the
cross section we made from material
select the material we just made and for
your bar orientation to find a vector
that goes in the y-direction one inch so
open 0 1 0 so 0 in the X 1 on the wines
around the Z hit OK or for application
region select the beam element filter
tool select element 2 at is select
element 3 and that it hit OK and now if
applied or assign the material in
cross-section to these two top elements
not to defy my damper for element 5
under windy properties look for damper
and here it is call this damper from an
input properties I have three values to
analyze I'll first use 2.5
the degree of freedom is you why
click okay for your application region
select this member add it okay and apply
next someone will define my spring so
under wendy property find the spring
icon and we'll call this property k
under input properties the constant is
500 delete this coefficient for damping
and the degree of freedom is UI again
hit okay for application region select
these two side members and again you
have to have this beam element icon
selected hit OK and apply now I can move
on to my boundary conditions tab I need
to make a new load case so click create
call this one simply LC and the type is
time dependent and that apply and you
need to define my load at this node so
under lbc fields click non-spatial here
I'll just call it load and the domain is
frequency and my input data I'll import
that CSV file I mentioned at the
beginning of the video hit apply and
notice it dropped all the values from
the CSV following here hit OK hit apply
at the bottom or hit enter make sure
it's set it feels load created now I
want to apply this load here so under
nodal force click force call it f under
NEPA data will give it a value of 0 1 0
and the adjacent box select this load
click OK in per application region we're
working with just the FEM so select FEM
and select this node click Add ok and
apply that's been added next time we
need to define displacement constraints
so I'll call this 1 1 3 4 5 6 and for my
input data have translations in the 1
on preventing translations on the 1 and
the 3 improving rotations about the X
the Y and the Z hit okay if your
application regions select all the nodes
added ok and apply there's one last one
I needs to define I'll call it 2 for
this one I'll prevent translations in
just the two direction and the rotations
are free so leave a blank hit OK for
application regions select this bottom
node node to add it ok and apply next I
can move on to my analysis so under an
analyzed entire model change the
solution type to frequency response
using the direct formulation and hit OK
under sub cases we are modifying the LLC
sub keys so click sub case parameters
and make sure it sounds LC here click
the final frequencies we are going in
from 0 to 30 type in 30
make sure it's s 30 here we are doing 60
increments make sure it says 60 here hit
OK
hit OK here and don't think I have to
modify anything else hit apply make sure
you get this feedback here click cancel
for your sub case select we don't want
to run the default sub case we want to
run the LC sub case they'll see sub case
has all the boundary conditions we've
defined so far hit OK and it apply click
X DB and hit apply to important results
under results we want to view a graph of
the acceleration at this point
so click graph click this icon expand it
and select all the results and or we
want to view the displacements that is
select displacements I'll leave that as
magnitude here I'll select note three
and I'll hit apply and if I compare this
to what we are expected to get you'll
see we we get a graph or a plot similar
to the one in the example next what I
want to go ahead and do is run the
analysis again for the next damping
coefficient before that I want to
improve hi I can read the numbers so let
me make this fixed I make this fix so
when I apply again I better able to read
the numbers quickly here under plot
options I'll save this graph as C equals
2.5 and the reason I'm doing this is
because next time I run this analysis
and do another graph I can hide the
result and overlay them so I get a final
view of all three damping coefficients
and it's time to go ahead and run the
next damping coefficient so here under
properties you want to modify the damper
so right-click and modify it was
previously 2.5 we'll make that a 10 now
hit OK and apply to modify it under
analysis simply analyze the entire model
again and hit apply will overwrite the
previous files once that an analysis is
done will import the xtb results do the
same thing results graph pick all the
results displacements I'm using the same
node this time we'll save this as C
equals 10 and we'll hit apply and right
now you'll notice that the graph was
created but it's behind it
I can go to home Tao of U ports and I
get this so now I can plot them one on
top of each other and so I think here we
go
I'm gonna say this just to be sure so C
equals it's apparently retain the old
one
anyways I'll make sure to leave this
alone for the next analysis and I'm
gonna see that again we get a similar
plot shown here and you'll see that they
actually corresponds to these values so
a value point one five eight six here
and a value of what looks like point
zero three seven nine so that would be
here and then the next one for damping
coefficient of 30 we are expected to get
a value of point zero one three to let
me go ahead and do that X under
properties modify the damper and give it
a value of thirty this time and hit
apply to modify it under analysis go to
analyze entire model and hit apply and I
override the previous files next I want
to put the results so click X DB and hit
apply under results click graph expand
all the results select all of them pick
displacements here make sure you see
this one C equals thirty and hit apply
so now I have the various plots here you
can see they range from zero to thirty
from zero to point one six and when we
compared to here that's what we do get
make sure to save and this concludes
that this example