Decision Presentation - Ohio University · FMEA • Roll cage collapse due to frontal crash ... •...

Decision Presentation:

Frame

Tyler Bork

Friday, February 10, 2006

Agenda

• Frame– Past to Present

• Assembly• Mock-Up • FMEA• Stress Analysis

2

Initial Frame Design

Redesigned Initial DesignInitial Design

3

Refined Frame Design

New Design from Scratch

Final Design

4

CAD Assembly

5

Full-Scale Frame

6

Operator Position

7

Mock-up Conclusions/Plans

• Overall Visibility: good• Accessibility: good• Overall Look: Is something consumers

would like/approve

• Future Plans include adding weather protection for further visibility questions

8

FMEA

• Roll cage collapse due to frontal crash• Roll cage collapse due to roll over• Collapse of control-arm frame posts• Steering linkage disengagement• Loosening of seat• Overloaded bending of steering column• Roll cage bending when supporting weight at contact point• Floor support bend due to sudden shock• Storage compartment overloading• Adjustable seat malfunctions• Impact failure to control/swing arm connections• Tipping due to off center loading• Person stands on edge and vehicle tips over onto them• Seat belt connections loosen• Suspension spring failure• Environmental protection tearing/breaking when hit with object• Seat springs overload/break• Detachment of motor and housing

9

Detailed FMEA Analysis

Worst-Case Stress Application Frame Failure

Failure ModeSEV

OCC

DET

RPN

Swing Arm Connection Failure 8 5 8 320

Recommendations: add some sort of additional support that would keep swing arm temporarily functional in the event of a failure

10

Stress Analysis Concentration

11

Rear Forces

12

Free Body Diagram

½ Fr

½ Fr

FD

FD

Fy

Fy

Fx

Fx

Front ofVehicle

0

θ1

θ1

θ2

θ2

13

Worst Case Scenario

• 15 ft radius, 10mph

• Weight Transfer or Body Roll

• Accelerating into turn (max Torque)

• Estimate Loads @ 4 different points

14

Weight Transfer for Turn

Total Weight 800 lb (Team Skid Mark)Weight transfer =

( acceleration x Weight x Height of CG ) / Track width

215.6 lb

277.75 lb

144.4 lb

162.25 lb

100 lb

535 lb

80 lb

70 lb

180 lb

220 lb

180 lb

220 lb

15

Material Selection

xzτ

- Unknowns = D, d- Use manufacturer value

xσ

( ) ( )

( )

( )2

8.12

6

2

464

2

22

22

2

2244

dDd

dDd

Q

QT

dD

F

dD

DM

xz

x

AxialBendingx

−+⎟

⎠⎞

⎜⎝⎛

−⎟⎠⎞

⎜⎝⎛

=

=

−+

−

⎟⎠⎞

⎜⎝⎛

=

+=

π

π

τ

ππσ

σσσ

16

Material Selection

• Use Factor of Safety of 3- Model approx. represents system- Fairly representative material test data

• Inquire machineability, cost, availability• Create MatLab Program• FEA Validation• Analyze other potential worst-case scenarios

17

QUESTIONS

18

Refined Mock-up Materials

• Materials Used:• Finalized Frame Design (Solid Edge drawing)• Schedule 40 ½” PVC• Tape Measure• Duct Tape• Metal Tie Wire

Total Material Cost: $25

19

System of Equations

)cos*()*()cos2

*()cos2

*()*(

)sin(22)sin2

(2

)cos(22)cos2

(2

25413121

21

21

θθθ

θθ

θθ

Dxrr

xyo

Dxr

Dxr

x

FlFlFlFlFlM

FFFFy

FFFF

++−−=

++=

++−

=

∑

∑

∑

20

½ Fr

½ Fr

FD

FD

Fy

Fy

Fx

Fx

Front ofVehicle

0 θ1

θ1

θ2

θ2

Future Analysis

• Creation of shear and bending moment diagrams

• Analysis of stress due to bending moment and selection of suitable material– Based on material strength needed vs. tubing

thickness• Create MatLab or Microsoft Excel Program• FEA Validation

21