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### Author Topic: Discretization of Ply Drop Offs  (Read 7190 times)

#### hyperuser

• Client
• Posts: 7
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##### Discretization of Ply Drop Offs
« on: February 15, 2010, 11:54:49 PM »
In reading your article, "Analysis Methods used on the NASA Composite Crew Module (CCM)" (found at: http://www.hypersizer.com/dload/aiaa08_analysis_methods_CCM.htm),   it's evident that the ply drop off for the sandwich panel was greatly refined between the preliminary (Fig 14) and final (Fig 18) sizing.  If I understand it correctly, it seems that the PCOMP cards from Fig 14 were broken up into finer slices to arive at those found in Fig 18.  How were the PCOMP cards broken up?  Was this done manually through an iterative process of checking the FEM loads or is Hypersizer able to suggest how the elements in a PCOMP card can be separated out?  Additionally, I read a separate post dealing with the use of an equivalent orthotropic material; can this be used to acheive the sizing found in your paper?

#### James

• Posts: 255
•
##### Re: Discretization of Ply Drop Offs
« Reply #1 on: April 26, 2010, 01:26:16 PM »

The equivalent orthotropic sizing is "step 1" or our new 7 step optimization method.  By creating homogeneous materials from a range of fiber orientations the panel object is sized to determine a target thickness.

Based on this target thickness and fiber orientation, the number of ply drops/adds is calculated across adjacent component boundaries.  Then by finding multiple designs that pass all active failure criteria, the facesheets are changed and the ply drops are reduced.  At this point we are still using the effective laminate (aka equivalent orthotropic) sizing method.

Then the target layups are created for each facesheet.  This is when we transition to discrete layups, where the layup sequence is specified.

This process may be better understood by reviewing our graphics user manual.

ref: HyperSizer Graphics User Manual v5.6

On our website:
http://hypersizer.com/documentation.html

-James