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1
Thanks, Max.

If we use symmetric laminate for each facesheet, we don't need to consider this case. In practical use, however, we sometimes meet this condition for very low loading sandwich structures. In general we seldom use sandwich structure with a thick facesheet.
I hope this mirror facesheet sizing is possible in Hypersizer sometime.

Pleased to communicate with you.

Changmin
2
Changmin,

Sorry for the initial slowness responding to your question. Glad to hear that you found a solution that is working for you!

Unfortunately, the backdoor option you referred to in your initial post, "TrussCore Sandwiches - Generate Only Symmetric Cross-Sections", does not work for honeycomb or foam sandwich concepts.

There is not a perfect solution to this at the moment. Your likely best option is to use laminate families, with the facesheets having mirrored sequencing. This will ensure that as long as the facesheets are the same thickness that you will have a symmetric cross-section.

Hope this helps!

-Max
3
Hi, Max
Thank you for your assistance.

1. Yes. Rapid sizing is for setting variables in detailed sizing. As I mentioned, when I ran set variables, then top and bottom faces was automatically linked again in tooling rules. After removing link again, I got the discrete laminates for each top and bottom faces separately.

2. No. I used only first plies in top face and last plies in bottom face in layup rule, and the others such as symmetry, balance etc. were not employed. In ply angle rules, min. 2 plies and 10% of 45 deg. Minimum zero percentage for 0 and 90 deg were applied.

While I have been waiting for your reply, I have found a solution for this by using "material family" for top and bottom surfaces, but I would like to look for a more general way.

Thanks.
Changmin
4
Hi Changmin,

I have a couple of questions to clarify your process so that I can help you get it working again.

It sounds like you are using rapid sizing so that you can run set variables for detailed sizing, and then running detailed sizing with discrete laminates. Is that correct?

Do you have any other stacking rules other than the facesheets be mirrored about the core?

Thank you,

-Max
5
I have been trying to size a sandwich panel structure fully symmetric with unsymmetric facesheets such as [45/-45/core/-45/45], /45/0/core/0/45] etc. in order to Bij=0  Trying several times with various options, I found a solution finally by using backdoor parameters, which Hypersizer answered in user forum in 2014. The successful procedure is as follows:
1) backdoor data set
     Geometry Check-Beam/TrussCore Sandwich-Generate only Symmetric Cross-Sections: Yes
2) Layup Rules(Top & Bottom face)
     Unchecked: Symmetry, Balance
     top: first plies [45/-45..], [45/0..] etc
     bottom: last plies [-45/45..], [0/45..] etc
3) Tooling rules: unchecked link option
4) Rapid sizing
5) Detailed sizing set(necessary for design variables set)
    a. applied set variables, then facesheet link option was automatically set to "checked" in tooling rules
    b. I did "unchecked" facesheet link option again(important!!)
6) Detailed sizing
7) Confirm sizing with Bij=0

Only this process makes possible to size symmetric whole sandwich structure.

HOWEVER,
when I expand this procedure to 6 plies of top and bottom facesheets with only two first and last plies set, I failed. Hypersizer gave me same thickness for top and bottom facesheet, but not the symmetric cross section nor ply percentage. Of course, Bij is not zero.

Could you check this, and suggest any solution for symmetric cross section design of sandwich panel?

Thanks.

Changmin.
   
6
Analyzing & Optimizing Stiffened Panels / Hat Bonded Smeared Panel Sizing
« Last post by loganbthomas on July 15, 2021, 08:39:17 AM »
I am using the Hat Bonded Concept using the detailed sizing, smeared panel approach. I've been looking at the weight differences when using various numbers of stringers in the skin bays. For example: 1 stringer, 2 stringers, 3 stringers, and 4 stringers in the bays. It's my understanding from reading the HME documentation for smeared panels that for Hypersizer to understand how many stringers are effectively in the bay using the smeared panel approach I should divide the appropriate buckling span by the number of stringers and input that value in the Spacing dimension for the Hat Bonded Concept. Is this approach correct?

In addition, after looking through the HME documentation for Geometry Cross-Section Checks it looks like for the smeared panel analysis to be considered valid there needs to be 3 stringers in the bay according to Geometry Rule 40. Does this mean that even though I input the Spacing dimension such that there should be 1 stringers, 2 stringers, or 4 stringers that Hypersizer will still analyze the bay as if there were 3 stringers?
7
There is not a 'create component' method. Creating and editing component membership touches too many database tables.

A work around is to create assemblies, by element, through the FEM viewer > Assembly > Create multiple assemblies by specifying input files...

The input files can be comma-separated lists of elements. A unique assembly will be created for each input file selected. When elements that are members of the same component are split into multiple assemblies, new components are created to enforce the rule that components can only live in one assembly. After this process is run you could reassign the new components to the original assemblies using the VBA script.

I hope this is helpful.

-James
8
Analyzing & Optimizing Stiffened Panels / Re: FEA Loads - Peak Element Filtered
« Last post by James on July 08, 2021, 07:45:30 AM »
I'd like to add that the peak element processing is repeated for every unique thermal set and/or assigned reference temperature. So if you have 2 unique thermal sets, then you get two blocks of processed peak element forces. During sizing, both blocks are checked.

I hope that's helpful.

-James
9
Hello oyama,

you can use the "Stiffness Requirements File" in Express by defining the file path in the: Analysis Criteria -> Stiffness Criteria dialog.

This way, you can define a minimum required stiffness (ABD matrix diagonal) for every individual element in your model.

The file format is as follows:
___________________________________
-1
#of Entries (i.e. number of elements you want to define a stiffness target for)
ElId, [dummy], A11, A22, A33, D11, D22, D33

-1
____________________________________

A simple example file defining the minimum (required) stiffness for elements with ID 1 through 10 is attached to this post.

Now, during element sizing optimization, these minimum stiffness requirements will be fulfilled (if your design restrictions allows for it; e.g. if max gauge is high enough for your chosen material).

I hope this helps!
-- Bertram
10
Hi,
How can I define "Stiffness Requirements File"?

I use Express for sizing composite structure, and I try to optimize with respect to the stiffness(Nodal deformation), but I don't want to use iteration. Then, I try to define "Stiffness Requirements File".

Any help would be welcome.

Sincerely,
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