Comparing the Impact Resistance of Various Materials Struck by a Projectile

                                         PURPOSE

The purpose of this experiment was to determine the impact resistance of various materials struck by projectile such as a paintball.

I became interested in this idea when I heard that body armor blocked bullets enough to keep from penetrating, although it would knock the wind out of you.

The information gained from this experiment could affect the designs of body armor for soldiers and police officers. It could show the government cost-effective materials to use in the future. 

HYPOTHESIS

My first hypothesis was that the neoprene would protect the most when used alone.

My second hypothesis was that the Cordura nylon would protect the least when used alone.

My third hypothesis was that the combination of neoprene and the high-density foam would protect the most in combination.

My fourth hypothesis was that the combination of High Density Foam and Mylar would protect the least in combination.

I based my hypothesis on information from various Internet sites explaining that neoprene is used in a lot of paint ball armor.

EXPERIMENT DESIGN

The constants in this study were:

•    The area of the Styrofoam

•    The thickness of the Styrofoam

•    The amount of material used

•    Distance the paintball gun is from target

•    The type and size of paintballs

•    The type and power of the paintball gun

The manipulated variable was the type of materials used to cover the Styrofoam target. 

The responding variable was the depth of the dent made in the Styrofoam target. 

To measure the responding variable, I used a micrometer accurate to thousandths of an inch.

                                     MATERIALS

QUANTITY	ITEM DESCRIPTION
2	2-by-4 sheets of Styrofoam that is 20cm thick
1	Spyder VL Lynx Paintball marker
100	Big Balls .68 caliber Paintballs
1	T-shirt
1	Sweatshirt
1	Jacket
1	Micrometer (Machinist’s Depth Gauge)
1	Neoprene Wetsuit
4	20cm by 20cm pieces a high density foam
4	20cm by 20cm sheets Mylar
1	1/2 yard by 60 in Cordura nylon
1	Sheet of plywood about 10cm thick
5	Wooden Stakes

                                 

PROCEDURES

1.    Gather Materials

a.    Buy Paintball marker and paintballs.

b.    Pick up wet suit from dive shop.

c.    Buy 20cm by 20cm sheet of Mylar.

d.    Buy 500 X 152cm piece of1050 Denier Ballistics Cordura nylon.

e.    Buy 20cm by 20cm piece of high-density foam.

f.    Get 10cm thick piece of plywood and 5 wooden stakes

g.    Get one old sweatshirt, one old jacket, and one t-shirt.

2.    Setup Experiment

a.    Cut Styrofoam into equal sheets of 20cm by 20cm.

b.    Saw 1 stake in to two 8 1/8in pieces.

c.    Saw another stake into two 10in pieces.

d.    Then screw 1 of the 8 1/8in pieces vertically on to plywood in center.

e.    Then screw the other piece vertically 10in to the right.

f.    Then screw the 10in pieces on the top and bottom of the 8 1/8in pieces making a square  frame.

g.    Put one test material on each labeled separate sheet of Styrofoam.

h.    Create several combinations of protective materials. Use each of the following:

i.    Neoprene + High Density Foam

j.    Neoprene + Cordura Nylon

k.    Cordura Nylon + High Density Foam

l.    Mylar + High Density Foam

m.    Set the plywood upright against fence.

n.    Load paint ball marker.

3.    Conduct the Experiment

a.    Put each material in wooden frame.

b.    Fire at material on one Styrofoam sheet from 5 meters away three times.

c.    Repeat steps 1 on each material.

d.    Take material off.

e.    Take to Kelly Conolly at Smith inc. with the micrometer to measure the indent in the Styrofoam with micrometer.

f.    Record depth of craters on a chart.

RESULTS

 The original purpose of this experiment was to determine the impact resistance of various materials struck by a projectile such as a paintball.

The results of the experiment were that Cordura Nylon protected best for the single materials. The combinations of Neoprene and Cordura Nylon, Neoprene and High Density Foam all protected completely. Out of the single materials Mylar protected the least. Out of the composites the combination of High Density Foam and Mylar protected the least.

CONCLUSION

My first hypothesis was that the neoprene would protect the most alone. The results indicate that my first hypothesis should be rejected, because neoprene did not protect the best, Cordura Nylon did.

My second hypothesis was that the Cordura nylon would protect the least alone. The results indicate that my second hypothesis should be rejected because the Cordura Nylon did not protect the worst, Mylar did. 

My third hypothesis was that the combination of neoprene and the high density foam will protect the most. The results indicate that my third should be accepted because the Neoprene/High Density Foam combination did protect the best. Although one other combination protected just as well.

My fourth hypothesis was that the combination of High Density Foam and Mylar would protect the least. The results indicate that my fourth hypothesis should be accepted because the combination of High Density Foam/Mylar did protect the least.

After thinking about the results of this experiment, I wonder if there would be a way to make an inflatable or “bubble wrap” style composite that used air bag materials perhaps bonded to thin ceramic plates.

If I were to conduct this project again I would make bigger targets, and find a flatter material to shoot at. I would do more trials and use a more powerful projectile.

Researched by ---- Jack C