universidad de oriente sef 2009

APPENDIX B-1 FSAE STRUCTURAL EQUIVALENCY FORM

This form must be completed and submitted by all teams no later than the date specified in the Action Deadlines on specific event website. The FSAE Technical Committee will review all submissions which deviate from the FSAE rules and reply with a decision about the requested deviation. All requests will have a confirmation of receipt sent to the team. Structural Equivalency Forms (SEF) and supporting calculations must be submitted electronically in Adobe Acrobat Format (*.pdf). The submissions must be named as follows: schoolname_sef.pdf using the complete school name. Please submit to the person indicated in the Action Deadlines for each event. University Name UNIVERSIDAD DE ORIENTE Car Number(s) & Event(s) # 24 FORMULA SAE CALIFORNIA Team Contact Simn Nuez E-mail Address [email protected] Faculty Advisor Flix Payares E-mail Address [email protected]

Deviation Requested

No Deviations

Rule No.

Rule Description Design Description

3.10 Main Roll Hoop Material 26.7 mm x 2.77mm Round 3.10.6 Main Roll Hoop Attach. to Monocoque 3.11 Front Roll Hoop Material 26.7 mm x 2.77mm Round 3.12 Main Roll Hoop Bracing 3.13 Front Roll Hoop Bracing 3.14 Monocoque Bracing Attachment 3.18 Front Bulkhead 26.4 mm x 2 mm Round 3.18.4 Monocoque Front Bulkhead 3.19.4 Front Bulkhead Support 26.4 mm x 2 mm Round 3.19.5 Monocoque Front Bulkhead Support 3.20.3 Impact Attenuator Attachment 3.20.6 Impact Attenuator Anti-Intrusion Plate 3.24 Tube Frames Side Impact Structure 26.4 mm x 2 mm Round 3.25 Composite Monocoque Side Impact 3.26 Metal Monocoque Side Impact 5.2.2 Monocoque Safety Harness Attach. 5.4.4 Shoulder Harness Bar

Attachment Checklist (make sure all are included in your report) Receipt, letter of donation or proof for non-steel materials (composite, honeycomb, resin, etc). Properties for all non-steel materials Holes drilled in any regulated tubing require a deviation, include area and moment of inertia

ATTACH PROOF OF EQUIVALENCY

Please see "Structural Equivalency Guide" on SAE website for more information about the proof of equivalency.

TECHNICAL COMMITTEE DECISION/COMMENTS ______________________________________________________________________________

Approved by__________________________________________ Date_____________

NOTE: THIS FORM AND THE APPROVED COPY OF THE SUBMISSION MUST BE PRESENTED

AT TECHNICAL INSPECTION AT EVERY FORMULA SAE EVENT ENTERED

2008 SAE International. All Rights Reserved. Printed in USA. 2009 Formula SAE Rules

Is proof of equivalency for your design required for any of the rules? ___Yes. Rule(s) deviated (indicate which below) __ No. Chassis did not deviate from baseline requirements

22000099 SSTTRRUUCCTTUURRAALL EEQQUUIIVVAALLEENNCCYY

CCAARR NNUUMMBBEERR 2244

STRUCTURAL EQUIVALENCY FOR MAIN ROLL HOOP AND FRONT

ROLL HOOP MATERIAL

Figure N 1. Circular Cross Section of the Main Roll Hoop and Front Roll Hoop

The properties of the selected material are:

1020 STEEL

Property Value Units

Elasticity Modulus 200 x 109

N/m2

Poisson Coefficient 0,29 NA

Shearing Modulus 7,7 x 1010

N/m2

Density 7900 Kg/m3

Ultimate Strength 379 x 106 N/m

2

Yield Strength 207 x 106 N/m

2

Thermal Conductivity 47 W/(M,K)



According to rule 3.3.3.1 the tubing size required is:

OD 1.0 inch (25.4 mm) x 0.095 inch (2.4 mm)

or OD 25.0 mm x 2.5 mm metric

Material: minimum 0,1% carbon.

For 1020 steel we have a Modulus of Elasticity

E = 200 GPa

- Calculating its Area Moment of Inertia

44

64IDODIII yyxx

440206.00254.0

64I

4910591.11 mI

The Buckling Modulus is:

499 10591.1110200 mPaEI

2397.2318 NmEI

- The tubing geometry selected for our design is:

Round Tube

OD 26.7 mm x 2 mm metric

Calculating its Area Moment of Inertia

44

64IDODIII yyxx

4402096.00267.0

64I

491037.14 mI

The Buckling Modulus is:

499 1037.1410200 mPaEI

2064.2874 NmEI

Its proved now that our design achieves the restriction of the rule 3.3.3.1 by having a greater Moment of Inertia and exceeds Buckling Modulus.

Figure N 2. Rules cross section for Main Hoop



Comparison of the cross section (Bending Moment Analysis)

- For the rules circular cross section

22

14

IDODA

22

1 0206.00254.04

A

24

1 10734.1 mxA

- For the new circular cross section

22

24

IDODA

22

2 02096.00267.04

A

24

2 10148.2 mxA

Therefore, we can conclude that

A2 > A1

Let compare now the normal stress due bending moment in both cross sections:

- For the rules circular cross section Assuming we are working in extreme conditions for the ultimate stress that maximum

bending moment would be:

c

IM cumax

m

mxPaxM

0127.0

10591.1110379 296

max

NmM 904.345max

- For the new circular cross section

Now if we calculate the maximum normal stress produced by this bending moment in

our new cross section

I

cMu

max

491037.14

0134.0904.345

mx

mNmu

Paxu610555.322

This way we prove that in a maximum condition for the cross section of the rule 3.3.3.1

our selected cross section wont reach the maximum stress.



STRUCTURAL EQUIVALENCY FOR FRONT BULKHEAD, SIDE IMPACT

STRUCTURE AND FRONT BULKHEAD SUPPORT.

This report pretends to explain the reasons who lead our team to fill the structural

equivalency for the Front Bulk Head and the Side Impact Structure according to the

2009 FSAE rules (Show in fig. N 3)

Due to the several changes performed in our new chassis design, and considering the

note 2 of rule 3.3.1 that goes:

For a specific application, tubing of the specified outside diameter but with greater wall thickness, OR of the specified wall thickness and a greater outside diameter

to those listed above, IS NOT a rules deviation requiring approval.

We have decided not to show any stress, buckling and/or simulation to prove out that

this new selected tube cross section is according to the SAE 2009 rules due to the higher

outer diameter and wall thickness of our circular cross section in comparison of the

tubing specified in the rules. All this considering that the new cross section chosen for

the team is the one you see in the next picture.

Considering the new cross section of the Front Bulkhead Supports, we do not perform

any impact simulation in order to prove this frame geometry is safe enough due to

exceed cross section selected in our design.

Front bulkhead cross

section

OD= 26.4 mm t= 2 mm

Side Impact & Front

Bulkhead Support cross section

OD= 26.4 mm t= 2 mm

Figure N 3. Isometric view of 2009 Prototype.

universidad de oriente sef 2009

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