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Analyzing & Optimizing Stiffened Panels / Re: Regarding Cross sectional Analysis
« Last post by Stephen on March 23, 2020, 09:47:04 AM »
Hello,

Can you provide a little more information? Are you using the FEM viewer's "section cut" capability to compute EI using HyperSizer? How different are the values you're computing by hand compared to those from HyperSizer?

Things to keep in mind: tension vs. compression vs. average modulus, reference plane / shell or property offsets.

-Stephen
2
Analyzing & Optimizing Stiffened Panels / Regarding Cross sectional Analysis
« Last post by durai on March 21, 2020, 02:12:22 AM »
Hello Every one

We are finding difficult in validating NASTRAN CQUARD element meshed as box and estimating EI values for Isotropic materials, still Hypersizer we are finding different answer , any guidance pls

--
Thulasi Durai
India
3

Dear HyperSizer Customers,

We understand that many organizations are transitioning to remote workspaces due to COVID-19. As many of our customers rely on server licenses and desktop work machines, we recognize the difficulties of shifting to remote work.

Free Node-Locked License Offering
We’d like to offer HyperSizer customers free 60-day node-locked licenses to help maintain productivity while employees work remotely. If you’re interested, simply email license@hypersizer.com and we will get you set up for remote work.

Training/Help Resources Available
If you haven’t already checked them out, our training videos are available and free to all current customers. In addition to that, our full suite of help resources will continue to be available: https://hypersizer.com/support/.

Let us know if we can further assist.

Thank you,

The HyperSizer Team
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Analyzing & Optimizing Stiffened Panels / Re: FEA loads procesing for DSP
« Last post by Brent on March 11, 2020, 04:19:21 PM »
Hi David,

Answers numbered below:

  • Behind the scenes, they are exactly the same. The only feature that uses the different names are the 2D maps.
  • This flag is obsolete and is now the default behavior. Unfortunately we did not remove it from the interface. We will include the update on the next release. A little background, originally the segment bending moment contribution from the bar elements was only M1 or M2. This flag would allow the axial component of load in the bar element to contribute to the segment bending moment due to the shift in the neutral axis of the bar to the mid-plane of the skin. The later is now the default behavior. Sorry for the confusion.
  • The documentation is in work right now. Additionally, we will have an update to the Grid Stiffened Plugin to support the discrete cruciform component concept. There are some difference in the section properties calculations between the Grid Stiffened Plugin and the HyperSizer native approach.
  • Unfortunately HyperSizer does not report the tension and compression tables on the FEA Load Tab for discretely stiffened panels. The attached image shows some additional reporting that is accessible from the sizing form after analyzing a single component. These files have some tension and compression load details that you might find useful.
  • Correct, bar elements use the following equation for the tension and compression loops:
    Pavg + N*Sqrt(Sum(Px,e-Pavg)^2*Le/Sum(Le)), where "e" denotes element and L is length.
    Or more simply put for 0-sigma:
    Sum(Px,e*Le)/Sum(Le).
  • Good Catch! The documentation was incorrect for the equations you noted. See attached image for updated transformation equations 1 through 3. We'll update the documentation
  • Looking at the example provided. I noticed that you are combining a tension load state in the right skin with a compression load state in the stringer and left skin. Are you saying this is the behavior reported in HyperSizer?
  • Qx,seg is used in the calculation of the stringer shear load. You can verify this by switching between segment loads and object loads in the backdoor options.
  • HyperSizer v8 native criteria uses the ABD approach for computing the object loads.Regarding your question about tension/compression loops, are you asking about how are these loads fed into the plugin calculations or the HyperSizer native criteria calculations?

Lastly, can you provide the specific example you are struggling with?

-Brent
5
Analyzing & Optimizing Stiffened Panels / Re: Why use DSP?
« Last post by Brent on March 11, 2020, 10:56:09 AM »
Hi David,

Benefits of sizing with discretely stiffened panels(DSP) compared to stiffeners and skins separately:
  • Like you mentioned, DSP can account for failure modes which are dependent on the geometry and loads of neighboring structure. With this information, the effective area for skins and stringers are known and can be used for various analysis criteria. In addition to the failure modes you mentioned, DSP supports compression post buckling.
  • Reduce the number of sizing and FEA iterations. In the stiffener direction, DSP assumes strain and curvature compatibility between the stiffener and adjacent skins. Therefore, when sizing, this approach analytically accounts for local load redistribution.
  • The Grid Stiffened plugin package, provided in the install, supports DSP modeling. This plugin package has text book implementation of methods in addition to capability for tuning conservatism. Some of these features are missing from the standalone skin and stiffener criteria.

If the FEA and HyperSizer geometry match and the panel segment definition is typical, the summed panel load analysis should produce similar results to the object based analysis. But, as in the case you mentioned, when there are peaking loads or load reversals in the uniaxial direction of a DSP, then the segment approach could inaccurately capture these load states when using the 0-Sigma load extraction technique. From our experience, this is a corner case that can be addressed by using object loads or a different load extraction technique.

Important Points:
  • DSP still runs tension and compression sizing loops so it does't average tension and compression element loads. The tension/compression sizing loops have independent segment loads and object loads. 
  • Only the loads in the direction of the stiffener are summed for panel loads. All other directions of loads are treated as object based.

Please reach out if more explanation is needed. Provided below is a link to the Grid Stiffened Plugin package documentation in our help system.

Link to documentation: http://hypersizer.com/help_7.3/#Udef/Plugin-HS_plugins_grid_stiffened.php%3FTocPath%3DAnalysis%2520Plugins%7CPublished%2520Plugin%2520Packages%7C_____4

-Brent
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General Discussion / NEW HYPERSIZER VERSION 8.0.54 OUT!
« Last post by Jennifer on February 24, 2020, 05:43:45 PM »
We are pleased to announce the release of HyperSizer Version 8.0.54.
 
This is our official 2020 release of version 8 to all customers with current MSU. If you haven't updated your software recently, you should update to this one (8.0.54) as it is the official and supported version. This version is fully tested and is our official 2020 release.

What’s New in Version 8.0.54


Version 8 is downward compatible to version 7.0 and you will be able to upgrade your version 7 databases to version 8. Remember, this version requires a new license string, so contact Collier Research at sales@hypersizer.com to update your license or for more information.
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Analyzing & Optimizing Stiffened Panels / Re: FEA loads procesing for DSP
« Last post by David Hughes on February 21, 2020, 10:34:30 AM »
Hello again,

Is there a failure mode that uses Qx,seg? If not, please ignore question 7 in my previous message.

I'm struggling to calculate Mxx,seg with N-sigma method and the tension/compression loops. Could you please explain the calculation process?

Also, the DSP loads document (sect 3.4) states that the smeared ABD method is used to calculated object forces, whereas the grid stiffened plugin had a different set of equations for the reference stresses. What does v8 use now for the integral blade and cruciform concepts? How are the tension/compression loops fed into these calculations?

Regards,
David.
8
Analyzing & Optimizing Stiffened Panels / Why use DSP?
« Last post by David Hughes on February 20, 2020, 10:22:25 AM »
Hi,

What are the benefits of sizing with Discretely Stiffened Panels compared to sizing the Stiffeners and Skins separately?

If the FEA and HS geometry match, would it be best to set the backdoor setting "use summed panel loads for object analysis" to "No" to avoid unusual object loads calculated when combining segment load components from the tension/compression loops?

I believe one advantage of DSPs is that more global failure modes can be considered, including flexural-torsional buckling, plastic bending and crippling (inc. effective skin). Is this right? Are there any others that require the summed segment loads?

Kind Regards,
David.
9
Analyzing & Optimizing Stiffened Panels / FEA loads procesing for DSP
« Last post by David Hughes on February 20, 2020, 07:53:31 AM »
Hi,

I am trying to follow how HyperSizer is calculating the Discrete Stiffened Panel loads for technique 2 so as I can understand the limitations. Apologies for the long message, but I have a few questions:

1) When creating the segments there is an option to create a stringer or frame segment. What’s the difference?

2) After upgrading to v8.0.47 I noticed that there is a new DSM backdoor option:
"Modify technique 2 beam fea moments to account for stiffener height"
What does this mean? Is it something related to bar offsets, or is it the moment correction for Cruciform sections, or is it something else?

3) V8 now incorporates the integral cruciform concept into the native environment, however there is no specific documentation. Is it the same as the method/equations used for the Metal Grid Stiffened Plugin?

4) Within the FEA Loads tab why are the tension and compression tables empty?

5) Within the FEA Loads document, section 4 gives the equations for the N-sigma methods. Do similar equations apply for BAR elements using length instead of area? Also, I cannot match the standard deviation values. Is the equation missing an n term (where n=number of elems) or is it something else?
   SD = (Sum((Ni - Navg)^2*Ai)/(((n-1)/n)*Sum(Ai)))^0.5

6) Within the FEA Loads document for Discretely Stiffened Panels I believe the transformation equations are incorrect (eq. 1 to 3):
   Nxy = -Fx*cos(q)*sin(q) + Fy*cos(q)*sin(q) + Fxy(cos^2(q)-sin^2(q))
   Similar for Mxy
   Qxx = +Vx*cos(q)+Vy*sin(q)
   Qyy = -Vx*sin(q)+Vy*cos(q)

7) For the Discretely Stiffened Panel’s transverse shear summation (eq. 41), I’ve found cases when the skin load relieves the total. I haven’t noticed this for Nx,seg and I’m still working on Mx,seg. I believe the full Qx,seq equation is:
   Qx,seg = (V1 + sign(V1)*(Qxx,L*wL/2+Qxx,R*wR/2)))/(1/2*(wL+wR))
   Where:   V1 = if |V1,t|>|V1,c| then V1,t else V1,c
   Similarly for Qxx,L and Qxx,R
Test case;
   wL/2 = 100   wR/2 = 100
   Qxx,t,L = 0.5   Qxx,t,R = 6.0
   Qxx,c,L = -1.0   Qxx,c,R = -3.0
   V1,t = 200   
   V1,c = -500   
      
   V1 = -500
   Qxx,L = -1.0
   Qxx,R = 6.0

   Qx,seg = (-500 - (-1.0*100 + 6.0*100))/200 = (-500+100-600)/200 = -5N/mm
Note that the LH Skin is relieving the load.

Kind Regards,
David
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Software Installation / Re: Installation of v8.0.47
« Last post by Stephen on January 31, 2020, 08:49:25 AM »
Hi Ruben,

This looks like a licensing issue. I am reaching out via email for more information.

-Stephen
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