MSC Nastran; Patran Tutorial - Freebody Loads; Pinned Truss Analysis Video

in this example we'll be looking at the
free body loads of a pin truss
full details of this exercise on page
456 of the PDF linked in the video
description below this problem is
actually a continuation of problem e in
the scene PDF and that part I already
gone ahead and done the problem you can
watch it in youtube I suggest that you
watch this video first and then once
you're done with that watch this video
so let me go ahead and open bad motto I
made already so again this is at the end
of this video and I suggest you watch
this first let me go ahead and open that
truss and we've been asked to view the
free body diagram so before you analyze
this you have to do one thing go to
analyze entire model and you have to
modify the sub case so in this case it's
the default left case drop it in here
under output requests let me delete all
this actually you have to select
something called a grip point force
balance so make sure it says GP force
equals all fam here in the output
requests hit OK at the bottom or hit
apply here and you'll be asked if you
want to replace a little sub case you
simply hit yes it cancel and hit apply
and replace the old files now I'll
import my ex DV results and under
results hit the free body icon here I
can show you the free body diagram so
under display attributes I'll select
force component I'll select resultant
dimensions xy-plane and that looks good
to go so I'll pick two elements at a
time
so first let's see what they select they
show us the bottom bar and top so I'll
do that so the bottom hold the shift key
and select uh in my case its elements
one in five and hit apply I get a
tensile force of 363 pounds and the
tensile force of 640 at the top so 360
and 640 compression and that's what I do
get here
note if I were to add another element
and hit apply it will actually sum up
the components and we don't want that so
make sure to select the two members that
are not in contact next a view 0 bar
here and the member on the right so let
me go ahead and select this one and this
one so elements three and six in my case
so this is zero and this is in tension
363 pounds let me clear it let me view
this diagonal and this diagonal
hit apply so I get a tensile force of
nine hundred here in the compressive
force of five hundred so nine hundred
and five hundred and compression next a
view the free body forces moments for
the entire truss
so to do that go back to display
attributes and select for side moment
select results in XY plane and I think
this time we can clear this and just set
apply and so we have
or that's where we had our point load at
this pin we have a pretty much outward
force of 1,000 so what they get in they
get a inward force of what looks like a
lot 1,200 and that's exactly what we do
get and that's how you views a free body
diagram for your truss go to file save
and that concludes this example