×
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

Problems with Composite Layup

Problems with Composite Layup

Problems with Composite Layup

(OP)
Hi All,
I have been modelling a simple (0.050x0.025x0.005m) Aluminium plate, fixed round the edge. I predict the natural frequencies and mode shapes with frequency analysis and the forced response with steady state dynamics. This has been done with both 3D solid elements and 2D shell elements. All seems to work ok. I have attached the .inp file for the shell plate.

Next I add a viscoelastic polymer layer and another aluminium layer to add damping to the plate. When using 3D solid elements this is done by either:
-    Extruding on the plate surface where the damper is located and partitioning the separate layers.
-    Creating the separate layers and tying them together.

Natural frequencies, modes and the strain energy in the polymer layer are predicted using frequency analysis, and forced response is predicted using steady state dynamics.

I am trying to do the same with shell elements by creating a composite layup material, and applying this where I want the dampers. I create 3 layers:
1 – Aluminium constraining layer – material ALU – Thickness 0.001m
2 – Polymer damping layer – material POLYMER – Thickness 0.00013m
3 – Aluminium Plate – material ALU – Thickness 0.005m
I have also set the offset to bottom.

When I run this, the natural frequencies I see in the composite regions fall from 489Hz to 0.2Hz. I am assuming due to a very large drop in stiffness.

Does any one have any ideas where I am going wrong? I have attached the input files for normal plate and composite plate for any one who is interested.

Thanks in advance for your help.

Regards,

Nigel

Undamped Plate - <http://files.engineering.com/getfile.aspx?folder=82cb6027-a624-4265-8d47-442cac05a4f2&amp;file=Shell-Plate-No-Damp.inp>

With Composite Layer - <http://files.engineering.com/getfile.aspx?folder=b13c2046-90f1-41a3-84af-a1b6f42265e1&file=Shell-Plate-with-comp.inp>

RE: Problems with Composite Layup

(OP)
Does any one have any good tutorials on using the composite layup tool?

Thanks for your help,

Nigel

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