2012 Structural Equivalency Sheet (SES)

[RobbyObby]

Is anybody else out there just as confused with the new SES spreadsheet as me? Most of it really straightforward and just plug-and-chug.
Where I'm getting confused though is where you input the "Number of Tubes". For instance, on the "Front Hoop Bracing" sheet, the default number of tubes is 1, which I'm assuming is meant to be when viewing in side view. However, my Front Hoop Bracing consists of a "bent" tube, with a triangulating tube back to the Front Roll Hoop. So does this mean I now have 3 tubes? Or 2? The spreadsheet seems to multiply the A_cross by the number of tubes for the EI calculations. But this does not seem correct at all, and I'm confused as to how I should represet my specific layout in the sheet.
Also, default "Number of Tubes" for the Side Impact Structure is 3 (1 on top, 1 on bottom, 1 middle triangulating). However, the bottom tube on my frame is bent, so the triangulating tube is essentially 2 tubes in a "V" shape. Is the middle triangulating tube(s) simply represented as 1 tube?

I understand the reasoning behind moving to something like this, as it is indeed more thorough and means less work for the organizers, but it seems like there should be a more thorough "How To" sheet, due to the unfamiliarity from all the teams, especially newer teams.
I'd love to here some input.

[RobbyObby]

Is anybody else out there just as confused with the new SES spreadsheet as me? Most of it really straightforward and just plug-and-chug.
Where I'm getting confused though is where you input the "Number of Tubes". For instance, on the "Front Hoop Bracing" sheet, the default number of tubes is 1, which I'm assuming is meant to be when viewing in side view. However, my Front Hoop Bracing consists of a "bent" tube, with a triangulating tube back to the Front Roll Hoop. So does this mean I now have 3 tubes? Or 2? The spreadsheet seems to multiply the A_cross by the number of tubes for the EI calculations. But this does not seem correct at all, and I'm confused as to how I should represet my specific layout in the sheet.
Also, default "Number of Tubes" for the Side Impact Structure is 3 (1 on top, 1 on bottom, 1 middle triangulating). However, the bottom tube on my frame is bent, so the triangulating tube is essentially 2 tubes in a "V" shape. Is the middle triangulating tube(s) simply represented as 1 tube?

I understand the reasoning behind moving to something like this, as it is indeed more thorough and means less work for the organizers, but it seems like there should be a more thorough "How To" sheet, due to the unfamiliarity from all the teams, especially newer teams.
I'd love to here some input.

[AxelRipper]

I do agree that there should be a better explanation of what terms mean (such as what the number of tubes means).

I did just hear back from the rules committee on some parts though. There was an error where if you put in a square tube in the side impact, it would come up as illegal, but that has been changed.

[dsegs]

Is the ymax cell (C50) on the Laminate Test page read-only for anyone else? I can't seem to be able to edit it...

[Dan Jones FSUK]

Hi,

I co-authored the SES template, I will check this thread from time to time and implement fixes as teams find problems.

It would be appreciated if you could raise queries/suspected bugs as questions to the FSAE rules committee so we can formally track them though.

Robby - We will discuss how we would like you to handle bent tubes in place of single tubes during the Rules Committee meeting tomorrow and feedback to you as soon as possible.

You are correct that the "number of tubes" refers to the chassis in side view.

I've just double-checked the EI calculations in the front hoop bracing tab, they do not use the calculated cross-sectional area. Although write-protected all the formulae in all the tabs are still visible so you can check how the results are calculated.

I recognise that a more thorough "How to" document would be useful and this is something that I am still working on.

I hope you can appreciate that writing the spreadsheet in itself was a mammoth task completed in free time outside of normal working hours, we didn't want to delay it's release any further waiting for the completion of a thorough "How to" document.

Dsegs - You've found an error in the sheet, V1.0.2 will address this and be released soon.

Regards,

Dan Jones
Head Technical Judge
Formula Student UK

[Long]

This new document is a great way to organize this information. It is definitely a mammoth task to create and debug though.

We have a problem: we cannot paste pictures into the Chassis Pics tab. It is protected. This makes it impossible to post the required pictures.


Does anybody know how to fix it?

[pete.m]

On the welded tube inserts tab there should be an option to have "your tube" be a square tube. Currently it is assumed that "your tube" is round. Note, exchanging square tubes for round tubes (of same outer dimension and wall) is not a deviation from the rules.

[pete.m]

I've wasted alot of time figuring out how to submit the SES. So far I have gathered that the team captain has to create an account at fsaeonline.com (which requires the "registration order number" also known as "confirmation number" from registration). Now the team captain can sign in, but the link to submit documents cannot be found. Trust me, I've clicked on all the links available. Anybody else figured out how to submit the SES?

[Long]

After login from fsaeonline.com, go to My Submissions. It should go to a page where you could up load not only SES but also other documents like Impact Attenuator Report, Design Spec Sheet, etc.

[pete.m]

Thanks. Some other observations: The submission page can only be accessed by the user registered as team captain, as far as I've discovered. Also, the submission page was just made available Jan 09.

[WarriorRacing]

Our team is using 4130 1"OD round tube for all frame members and 4130 1"x1" square tube for all suspension mounting members. We are in compliance with all frame rules. I am trying to add the 4130 to the material data tab and it is asking for welded material strength. I am unsure of where to find this data. One team member who completed and SES in the past told me that if we are in compliance we only need to complete the first sheet of the SES.

1. Do we need to complete more than just the first sheet if we are in full compliance? I've tried to find a definitive statement about this in the rules but haven't had any luck.
2. If so, where can I find properties for welded 4130?

Thanks,
Steve

[RobbyObby]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WarriorRacing:
Our team is using 4130 1"OD round tube for all frame members and 4130 1"x1" square tube for all suspension mounting members. We are in compliance with all frame rules. I am trying to add the 4130 to the material data tab and it is asking for welded material strength. I am unsure of where to find this data. One team member who completed and SES in the past told me that if we are in compliance we only need to complete the first sheet of the SES.

1. Do we need to complete more than just the first sheet if we are in full compliance? I've tried to find a definitive statement about this in the rules but haven't had any luck.
2. If so, where can I find properties for welded 4130?

Thanks,
Steve </div></BLOCKQUOTE>

The Rules Committee makes no differentiation whether you are using 4130 or mild steel. All the baseline material properties already in the sheet are based on mild steel, so all you need to do is fill out every sheet (minus the monocoque sheets if you are running a tube frame) and simply input the tube dimensions and leave it as "Steel" under the "Your Tube" column. The sheet will do the rest. However you do still need to submit annotated Chassis figures highlighting the size and thickness of each tube, for visual reference.

[typehazard]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Long:
This new document is a great way to organize this information. It is definitely a mammoth task to create and debug though.

We have a problem: we cannot paste pictures into the Chassis Pics tab. It is protected. This makes it impossible to post the required pictures.

I have the same problem i would like if someone could reply to this.

Does anybody know how to fix it? </div></BLOCKQUOTE>

[typehazard]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Long:
This new document is a great way to organize this information. It is definitely a mammoth task to create and debug though.

We have a problem: we cannot paste pictures into the Chassis Pics tab. It is protected. This makes it impossible to post the required pictures.


Does anybody know how to fix it? </div></BLOCKQUOTE>

Hi Long
If you are still having problems with how to place the pics in the cahssis section, all you need to do i s go top the insert tab in excel and click on picture.

[Geoff H]

I just wanted to check the values being pumped out by the SES.
The current EI (stiffness) value being pumped out is typically around a third of that than what is calculated using the formula E*I=D=0.5*Ef*tf*h^2*b, which can be found in the Hexcel Sandwich Design manual, which is typically referenced in most Sandwich Design manuals and papers.

I just wanted to see if anyone found this issue as well, as playing around with the document, I've noticed the stiffness does not increase significantly with the increase in h (but keeping the same skin thickness of 0.3mm skins).


On a separate topic, I'm not entirely sure how the SES calculates the perimeter shear for the bulkhead support and the side impact structure.
Our team typically uses thin skinned aluminium, and adds on a layer of CFRP on top to allow it to physically resist puncture (for the perimeter shear test).
Is there a way to factor this into the SES?

[Geoff H]

To add to my previous post, I also looked over excel document which has the formula I=(b*tf^3-b*h^3)/12 , which completely negates the use of a core. However, in a sandwich panel, the core density is a major factor to the panels stiffness.

[MikeZ]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by pete.m:
I've wasted alot of time figuring out how to submit the SES. So far I have gathered that the team captain has to create an account at fsaeonline.com (which requires the "registration order number" also known as "confirmation number" from registration). Now the team captain can sign in, but the link to submit documents cannot be found. Trust me, I've clicked on all the links available. Anybody else figured out how to submit the SES? </div></BLOCKQUOTE>

pete.m, sorry to hear about the confusion. Sounds like you might need to talk to SAE and make sure your registration data is OK in the new system.

Just fyi, team members (not just captains) should be able to get to the document submission stuff too. Find out more in this other thread:
2012 Document Submission (http://fsae.com/eve/forums?a=tpc&s=763607348&f=442600868&m=73320623151&r=73320623151#73320623151)

If other people have questions feel free to post in that thread, or contact SAE directly for help. Thanks.

[Geoff H]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Geoff H:
To add to my previous post, I also looked over excel document which has the formula I=(b*tf^3-b*h^3)/12 , which completely negates the use of a core. However, in a sandwich panel, the core density is a major factor to the panels stiffness. </div></BLOCKQUOTE>

Tis appears the spreadsheet is correct.
I've been corrected.

[Geoff H]

Question:
Lets say you had a composite beam, like a layer of wood over a layer of aluminium as the skin of a sanwich structure.
How would the properties of the wood be included the the stiffness of the beam in the SES.

[S A N]

Hello,

We will be using Mild Steel for our chassis. But am unable to get any document from my dealer which confirms the yield strength & carbon content.

I would like to know if we are supposed to show documents (eg. a test certificate/lab report) proving the Yield Strength & Carbon content along with the pipe dimensions during Technical Inspection in FSG.

We meet the baseline properties & our equivalency is met.

[revolutionary]

^^ the SES is already filled out with the appropriate numbers for steel. You 'should' be able to just fill out the first two sheets per the hints on fsaeonline.com if you just have a basic steel frame.

[RENESIS]

The lamination's inner and outer skin must be the same. But we designed outer skin thicker than inner. Than we fill the SES with some deviation.

[RENESIS]

And we found more mistakes in V12. In the Mhoop Brace Spt tab, the E26 cell about tubes' EI, has the wrong formula, quoting C column instead of E column. And also tab of Front Hoop Bracing, Front Bulkhead, Shoulder Harness Bar Equivalency.