Cornell FSAE Monocoque Frame Overview

Alex Hsia

Cornell FSAE Monocoque Designer ’14

Layup Order

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Side Impact

Bulkhead

Support

Front Hoop

Bracing

Main Hoop

Support

Lip Rear

(Shoulder

Harness Bar) Bulkhead Engine Top Bottom Back Damper Lip Front

Lip Corners

Front Lip Thin

Lip Corners

Rear

1 T800H,45 T800H,45 T800H,45 T800H,45 T800H,45 T800H,45 T800H, 45 T800H, 45 T800H, 45 T800H, 45 T800H, 0 T800H, 0 T800H, 0 T800H, 0 1

2 T800S, 0 T800S, 0 T800S, 0 T800S, 0 T800S, 0 T800S, 0 T800H, 0 T800H, 0 T800H, 0 T800S, 90 T800H, 0 T800H, 0 T800H, 0 T800H, 0 2

3 T800S, 90 T800S, 90 T800S, 90 T800S, 90 T800S, 0 T800H,45 T800H, 45 T800H, 45 T800H, 45 T800S, 0 T800H, 0 T800H, 0 T800H, 0 T800H, 0 3

4 T800S, 0 T800S, 0 T800S, 0 T800S, 0 T800H,45 T800S, 0 .5 Core .5 Core T800H, 0 T800S, 90 T800H, 45 T800H, 45 T800H, 45 T800H, 45 4

5 T800H,45 T800H,45 T800H,45 T800H,45 0.75 Core T800H,45 T800H, 45 T800H, 45 T800H, 45 T800H, 45 T800H, 45 T800H, 0 T800H, 45 T800H, 45 5

6 1 Core 1 Core .5 Core 0.75 Core T800H,45 T800S, 0 T800H, 0 T800H, 0 T800H, 0 T800H, 0 .5 Core T800H, 45 T800H, 0 T800H, 45 6

7 T800H,45 T800H,45 T800H,45 T800H,45 T800S, 0 T800S, 0 T800H, 45 T800H, 45 T800H, 0 T800H, 45 T800H, 45 T800H, 0 T800H, 0 T800H, 0 7

8 T800S, 0 T800S, 0 T800S, 0 T800S, 0 T800S, 0 T800H,45 T800H, 45 0.75 Core T800H, 45 T800H, 45 T800H, 45 T800H, 0 8

9 T800S, 90 T800S, 90 T800S, 90 T800S, 90 T800H,45 0.75 Core T800H, 0 T800H, 45 T800H, 0 T800H, 0 T800H, 45 T800H, 45 9

10 T800S, 0 T800S, 0 T800S, 0 T800S, 0 T800H,45 T800H, 45 T800H, 0 T800H, 0 T800H, 0 T800H, 0 T800H, 45 10

11 T800H,45 T800H,45 T800H,45 T800H,45 T800S, 0 T800H, 0 T800H, 45 T800H, 0 T800H, 45 T800H, 0 T800H, 45 11

12 T800S, 0 T800H, 45 T800S, 90 T800H, 0 T800H, 0 T800H, 0 12

13 T800H,45 T800S, 0 T800H, 45 T800H, 0 13

14 T800S, 0 T800S, 90 T800H, 0 T800H, 0 14

15 T800H,45 T800H, 45 T800H, 45 15

16 T800S, 0 T800H, 0 16

17 T800H,45 T800H, 0 17

18 T800H, 0 18

Material Properties Tests

-100

0

100

200

300

400

500

600

700

800

0 0.005 0.01 0.015 0.02 0.025

Load

(lb

f)

Displacement

T800H [05] Tensile Coupons

Sample 1

Sample 2

Sample 3

-100

0

100

200

300

400

500

600

700

800

-0.005 0 0.005 0.01 0.015 0.02 0.025

Load

(lb

f)

Displacement

T800S [05] Tensile Coupons

Sample 1

Sample 2

Sample 3

Tensile strip modulus tests, T800H and T800S

Specimens were not broken in order to re-test to check for slippage in jaws

-100

0

100

200

300

400

500

600

700

800

900

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02

Load

(lb

f)

Displacement

M46J [05] Tensile Coupons

Sample 1

Sample 2

Sample 3

-100

0

100

200

300

400

500

600

700

0 0.005 0.01 0.015 0.02 0.025

Load

(lb

f)

Displacement

T300 [05] Tensile Coupons

Sample 1

Sample 2

Sample 3

Tensile strip modulus tests, M46J and T300

Tensile strip strength tests, T800H, T800S

0

500

1000

1500

2000

2500

3000

0 0.05 0.1 0.15 0.2 0.25

Load

(lb

f)

Displacement (in)

T800H [03] Tensile Coupons

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Load

(lb

f)

Displacement (in)

T800S [03] Tensile Coupons

Non-linear curve indicates slipping in jaws

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

M4

6J

Sam

ple

1

M4

6J

Sam

ple

2

M4

6J

Sam

ple

3

M4

6J

Sam

ple

4

T30

0 S

amp

le 1

T30

0 S

amp

le 2

T30

0 S

amp

le 3

T80

0H

Sam

ple

1

T80

0H

Sam

ple

2

T80

0H

Sam

ple

3

T80

0H

Sam

ple

4

T80

0H

Sam

ple

5

T80

0H

Sam

ple

6

T80

0H

Sam

ple

7

T80

0H

Sam

ple

8

T80

0H

Sam

ple

9

T80

0H

Sam

ple

10

T80

0H

Sam

ple

11

T80

0H

Sam

ple

12

T80

0H

Sam

ple

13

T80

0H

Sam

ple

14

T80

0S

Sam

ple

1

T80

0S

Sam

ple

2

T80

0S

Sam

ple

3

T80

0S

Sam

ple

4

T80

0S

Sam

ple

5

T80

0S

Sam

ple

6

T80

0S

Sam

ple

7

Mo

du

lus

(Msi

)

Sample

Tested Modulus of Prepreg Material

M46J Sample 1

T300 Sample 1

T800H Sample 1

T800S Sample 1

Tested moduli of materials all much lower than expected. Possible sources of error include slipping in jaws, compliance in testing apparatus, incorrectly designed test strips.

0

50

100

150

200

250

300

350

400

Stre

ngt

h (

Ksi

)

Sample

Tested Strength of Prepreg

M46J Sample 5

T800H Sample 12

T800S Sample 5

Tested max strengths are close to expected.

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.02

Stra

in (

in/i

n)

Sample

Tested Max Strain of Prepreg

M46J Sample 5

T800H Sample 12

T800S Sample 5

Tested max strains are also close to expected.

Rough analysis using ANSYS ACP

Figure 3. 3/4" Solid Carbon Hardpoint Test Panel

Hardpoint Analysis

Panel Bending and Pullout Tests

y = 28102x - 187.03

0

1000

2000

3000

4000

5000

6000

0 0.2 0.4 0.6 0.8

Load

(lb

f)

Displacement (in)

Hardpoint Test Panels

.75" HardpointPanel 1

,75" HardpointPanel 2

1" HardpointTest Panel

Series1

Linear (Series1)

y = 18119x + 21.204

0

1000

2000

3000

4000

5000

6000

0 0.2 0.4 0.6 0.8

Load

(lb

f)

Displacement (in)

Hardpoint Test Panels

.5" HardpointPanel 1

.5" HardpointPanel 2

Linear (Series1)

Factors of Safety over Core Failure

Front Lower Forward 3.859911 Rear Lower Forward 10.34577

Rear 7.427245 Rear 12.20871

Upper Forward 1.280878 Upper Forward 4.753317

Rear 2.530728 Rear 1.757584

Toe link 11.50272 Toe link 8.651866

Pushrod 1.954779 Pushrod 1.68903

Boundary Conditions for ANSYS Torsional Stiffness

ANSYS model predicts 4800 ft-lb/deg torsional stiffness

Figure 10. "Lozenging" Effect

Figure 11. Vector Principal Elastic Strain around Lip

y = 1538.5x

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

-0.6 -0.4 -0.2 0 0.2 0.4 0.6

Torq

ue

(ft-

lb)

Angular Displacement (deg)

Hub-Hub Torsional Stiffness

y = 4083.7x

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25

Torq

ue

(ft-

lb)

Angular Displacement (deg)

Monocoque Torsional Stiffness

Design goal: frame stiffness 10x overall torsional wheel rate

Overall

torsional

wheel rate 120 ft-lb/deg

vehicle 1553.03 ft-lb/degsuspension 2500 ft-lb/deg 12.5x wheel rateframe 4100 ft-lb/deg 20.5x wheel rate

ANSYS Corner Brake Bump

Factor of safety of >5 everywhere on body. Max strain of 18e-3 strain obtained from tensile tests

Stress Contour

patch load 217.5 lbf

upright height 6.7 in

hardpoint stiffness 28000 lbf/in

top A-arm load 89.74449 lbf

lower A-arm load 309.9383 lbf

top hardpoint deflection 0.003205 in

lower hardpoint deflection 0.011069

camber change at max

corner 0.122069 degCamber Compliance due to hardpoints

3 Point Bend Test Results

y = 6080.6x - 43.689

0

500

1000

1500

2000

2500

0 0.1 0.2 0.3 0.4 0.5 0.6

Load

(lb

)

Displacement (in)

3 Point Bend C

y = 6946.3x - 415.24

0

500

1000

1500

2000

0 0.1 0.2 0.3 0.4 0.5 0.6

Load

(lb

)

Displacement (in)

3 Point Bend A

y = 7586.5x - 57.412

0

500

1000

1500

2000

2500

0 0.1 0.2 0.3 0.4 0.5 0.6

Load

(,b

f)

Displacement (in)

3 Point Bend B

Manufacture Pictures

Core Sections and Core Splice

Figure 14. Three part cure (2 autoclave, 1 postcure) for improved surface finish

Cured Laminate