AARON THATCHERAND

SHANNON BRADHAM

May 1, 2009

BILL OF MATERIALPart

# Part name Quantity Total Cost ($)

Per part 1 Electric motor 1 4002 2x4 studs 40’ 24

37/8" Pillow

Block Bearing 4 254 Power Cord 1 20

57/8" Lovejoy

Couplings 1 206 3/4" OSB 12 sq feet 20

71/2" pipe &

fittings 14'  308 Hardware Kit 209 Angle Brackets 25 2010 Graphite 10 oz. tube on hand

= 579Total Cost of materials

COBALT CURENTLY USES ALUMINUM PLATES ENCAPSULATED INTO FRP LAMINATE FOR SCREW RETENTION .

FOR CERTAIN APPLICATIONS, COBALT HAS BEGAN TO REPLACE THE ALUMINUM PLATES WITH A MESH OF A COMPOSITE CALLED TREVIRA.

COBALT HAS ASKED PSU TO PERFORM CYCLIC FATIGUE TESTING ON PARTS THAT HAVE TREVIRA FOR SCREW RETENSION ON HINGE APPLICATION. ALSO TO COMPARE TRIVERA TO ALUMINUM PLATE FOR COMPARISON AND ANALYSIS.

The door assembly with the aluminum

insert was tested first.

•Using a 1/16 hp electric motor at 345

in/lb of torque to turn a ½” pipe shaft

at 8 rpm, the offset of the shaft forced

the door to close and the 20 ft /lb gas

assist pushed it back open. This

completed 1 cycle.

Several control points were

checked as each 1000 cycle point

was reached.

•A counter was used to record each

revolution as the shaft closed the

hatch.

•An 8mm

video camera was used to record

the procedure.

The door placement remained

dimensionally intact and the

screws holding the hinge to the

base and the hatch stayed in

place.

After 5000 consecutive

cycles the hinge attachment

showed no obvious failure

from fatigue. The only

noticeable change was that

the hinge pin had moved

outside the hinges about

½”.

The unit with the Trevira

composite was then set in

place and 1000 cycle

rotations were began on it.

Control points were

checked on it at the end of

each 1000 cycles to

determine if any

deformation or failure was

developing.

Once 5000 cycles were reached,

as with the other unit, there were

no observable or measureable

changes to report. The hinge

remained intact to each piece,

and the screws used to fasten the

hinge remained tight and in

place. There was no deformation

or change in dimensions from the

original condition.

Another mechanical

connection using the composite

in this test unit was the clip

used to attach the gas assist to

the base of the unit. This

connection also remained tight

and in its original place.

Check Gap

Check Position of all 6 Screws

Check Displacementand Dimensionaround the edge of the hatch.

Based on the results of the fatigue test, the two applications we tested that

use Trevira to replace aluminum inserts did not appear to exceed the

working strength of the composite. Considering the convenience of use

Trevira has in Cobalt Boat’s fabrications compared to the metal inserts, this

success should further justify its use.

Our team would like to express our appreciation in being given the

opportunity by Cobalt Boat to develop our Senior Project around the

subject of the use of composites in their line of outstanding powerboats.

The experience was interesting and challenging, giving us the opportunity

to conceive, design, develop and put to use a real world situation.