The Effect of Damping on a Shock Absorber

	Project title: The Effect of Damping on a Shock Absorber
Difficulty level:	High school
Main link:	None

Hypothesis:

My hypothesis is that the time that it takes for the piston to compress of the single and multiple holes will be very close if the total surface area is kept constant through out all the tests.
I base my hypothesis on the research that I have done and the experiments on damping that I have heard of. And from all of it I can hypothesize that if the total area of the single and multiple of the holes drilled in the damper the compression time should be the same.

Materials:

Fox shock absorber
3.81 cm hole saw drill bit
0.9525 cm drill bit
Electric drill
Birch plywood 2.5mm x6x12"
Stop watch
Vise grip
Lid to 35mm film canister
200 ml. cooking oil for shock fluid
X-Acto hobby knife
Tube of epoxy
Paint Brush
1.59 mm drill bit
2.78 mm drill bit
3.18 mm drill bit
3.97 mm drill bit
4.37 mm drill bit
5.95 mm drill bit
6.35 mm drill bit
202.4 grams weight
3.1 cm hole saw drill bit
0.9525 cm drill bit

The Procedure:

I. Setting up the shock absorbers for the tests.
1. Dismount the shock absorber,
2. Take the damper off.
3. Take the bushing off.
4. Pull the O-rings out of the bushing.
5. Place the bushing on the shaft.
II. Setting up the damper for the tests.
1. Place the piece of birch plywood in the vise grip
2. Drill out as many disks as you can out of the plywood because some might get damaged in the drilling with the whole saw drill bit.( at least seven)
3. Drill a hole in the center of the disk were the pilot hole of the whole saw drill bit using a 0.9525 cm drill bit.
4. Drill a 0.9525 cm hole in the center of the 35. 5mm film cap.
5. Take the Ex-Acto knife and cut off as much excess plastic, but still leaving an area for it to attach to the shaft and make sure the film cap doesn’t cover any of the wholes.
6. Apply the epoxy on the disk on both sides.
7. For damper number one single drill one 6.35 mm hole in the disk.
8. For damper number two single drill one 5.95 mm hole in the disk.
9. For damper number three single drill one 4.37 mm hole in the disk.
10. For damper number four single drill one 3.97 mm hole in the disk.
11. For damper number five single drill one 3.18 mm hole in the disk.
12. For damper number six single drill one 2.78 mm hole in the disk.
13. For damper number one multiple drill three 1.59 mm holes in the disk.
14. For damper number two-multiple drill one more 1.59 mm holes in the disk.
15. For damper number three-multiple drill two more1.59 mm holes in the disk.
16. For damper number four-multiple drill two more 1.59 mm holes in the disk.
17. For damper number five-multiple drill eight more 1.59 mm holes in the disk.
18. For damper number six-multiple drill two 1.59 mm holes in the disk for a total of sixteen holes.
19. Attach the right damper for the test to the piston rod

Results:

The original purpose of this experiment was to see if one big hole drilled into the damper in a shock absorber has the same reaction time to compress as a many small holes drilled into the damper of the shock absorber and keeping the area of the hole drilled constant.
The results of the experiment were that the larger the holes are the less amount of damping takes place and the smaller the holes are the greater amount of damping takes place. It also doesn’t matter if there are fewer or more holes in the damper because the compression time is too close to matter in a simple shock absorber.
See the tables and graph below for more information on the times of the shock absorbers.