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


Classical Laminate Theory (CLT) Composites Question

Classical Laminate Theory (CLT) Composites Question

Classical Laminate Theory (CLT) Composites Question

Hey guys,

can anyone shed some light on classical laminate theory (CLT)? Let's say I have a laminate made from 3 plies: 2 outter carbon fiber plies and 1 inner fiber glass ply...

I go through the Q, Q bar, and ABD matrices steps... Now, lets say i have my inverse ABD matrices. this can be multiplied by the force and moments (N & M) vector to get me the strain and curvature (epsilon & k) vector... Ok, so I calculate it out and now I have my strain... I can find stress too (only per ply)...

Can any of this data get me the displacement or the young's modulus of the entire laminate?! It seems like CLT is solely for stress and strain and doesn't take into account any other important factors... Just not sure how useful it really is other than stress or strain. One might argue that you can use Hooke's law after (sigma = E*epsilon), but this is only for isotropic materials. Not orthotropic.

Let me know.

RE: Classical Laminate Theory (CLT) Composites Question

Modulus of the entire laminate is calculated from the inverseA matrix. See any CLT text.

Displacement is a structural response. The CLT stiffness or compliance matrices are plugged into beam or plate theory equations, or a FEM, or such and displacements can be determined.

RE: Classical Laminate Theory (CLT) Composites Question

Hey @SWcomposites,

Thank you so much! That actually helps a lot. I have done a lot of reading on CLT but haven't seen anything about how the modulus is calculated from the inverse A... Just curious if you could point me to a book or a formula?

and that makes sense about the displacement. Thank you.

RE: Classical Laminate Theory (CLT) Composites Question

This is for a symmetric laminate. For an unsymmetric laminate, it is not as straightforward (and not shown).


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!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close