×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Modelling of Inflatable Beam Using Ansys

Modelling of Inflatable Beam Using Ansys

Modelling of Inflatable Beam Using Ansys

(OP)
Hello,

I have designed a mathematical model (theoritically) for an inflatable beam which comprises of internal pressure 4.5 Psi. One side of the beam is hinged and the other is simply supported. The specifics of the beam are:
Length : 1820mm
Diameter: 430mm
Thickness: 25mm
Internal Pressure:4.5 Psi
Material: Nylon
Internal Fluid: Air

Now, I have to validate my theoritical model by doing the same with ansys and compare the two results. Im unable to model the Inflatable beam in Ansys. Please help me with the modelling in ansys and to input properties of air inside the beam.

RE: Modelling of Inflatable Beam Using Ansys

As far as I can see, there are two effects related to your problem:
- the change in volume due to any deformation under load that's going to change gas pressure
- the tensile stress induced by pressure in the walls that's going to set farther away the local or global buckling of walls
The first effect is a non linear one and would require an analysis with the deflection related stresses turned on, but I don't think it is particularly important, at least for reasonable deflections.
The second one can be accounted for by superposing the known stress distribution due to pressure to the distribution due to other loads and using the resulting stresses to check for buckling.
Am I missing something?

prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads

RE: Modelling of Inflatable Beam Using Ansys

(OP)
Prex,

U are right! after a certain limit of loading, the behavior of the beam tends to become non-linear, that's the point where the beam starts to 'wrinkle'(total non-linear behavior) . Though all that can be obtained mathematically, modelling it numerically is being a challenge! Your response is perfect, it behaves like the way you've mentioned. Any views with regard to numerical modelling?

RE: Modelling of Inflatable Beam Using Ansys

You could represent the gas as a solid with a Young's modulus equal to 3 times the bulk modulus, a Poisson's ratio of zero and a shear modulus as close as possible to zero. And of course you need a run with geometric non linearities turned on.  

prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources