Final Project - S12 and S21

1. 

   Imad Hanhan @ 2:24 pm on 29 Nov 2017

   Hello all,

   I'm working on calculating the stiffness matrix following the steps in the chapter. I computed the values and compared them to the values I get from SwiftComp. Right away I noticed that SwiftComp computes non-zero values for S12 and S21, where as my analytical solution had only diagonal terms.

   Looking at Equations 24 and 25 on page 11, I see that S12 and S21 are not included, and I believe this stems from the strain field expressions for epsilon_12 and epsilon_13, which only have kappa_1.

   So... either I'm incorrectly using SwiftComp and S12 and S21 should be 0, or (I think more likely) my analytical solution is wrong. Can anyone help me figure out how to compute S12 and S21? Are there changes that I should have made to the strain field expressions?

   Thanks,
   Imad

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2. 

   Wenbin Yu @ 9:37 am on 29 Nov 2017 — Edited @ @ 9:37 am on 29 Nov 2017

   Imad, you will see some difference between SwiftComp and your analytical calculations. I will not be surprised if extension twist coupling cannot be captured by analytical method. -------- Original message -------- From: "Imad Hanhan @ cdmHUB - The Composites HUB" <support@cdmhub.org> Date: 11/29/17 14:24 (GMT-05:00) ---- Emailed forum response from wenbinyu@purdue.edu

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3. 

   Imad Hanhan @ 2:40 pm on 29 Nov 2017

   Dr. Yu,

   Sounds good, thank you for such a quick reply.

   All the best,
   Imad

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4. 

   Kunal Samel @ 9:11 pm on 30 Nov 2017

   my analytical  S12 S21 aren't 0

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5. 

   Imad Hanhan @ 9:35 pm on 30 Nov 2017

   Hi Kunal,

   How are you calculating S12 and S21? Using equations 24/25/26 on page 11 of the handout I don't see any formulations for S12. I'm sure I'm missing something on my end, any information would be helpful.

   Thanks,
   Imad

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6. 

   Kunal Samel @ 10:03 pm on 30 Nov 2017 — Edited @ @ 10:04 pm on 30 Nov 2017

   First integrate (Sigma11)dA to get F1 as a function of e1,k1,k2,k3. then pick coefficient[F1,k1]

    

   now sigma 11 will contain k1 for general anisotropic or monoclinic stiffness matrix. The derivation in text uses isotropic material so that c15 and c16 for them is 0. so the sigma11 in text does not have k1 term but ours will

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