I am trying to find how much force in needed to break an egg in ballistics gel. Since I already know how much force it takes to break an egg on its own, I will be able to see how the force is transferred though the gel in the pressure wave.
I first cut a block of ballistics gel that was a bout a 14cm cube. I then took an empty asparagus can and used it to punch a cylinder to the center of the block out of the gel. The cylinder was about 5cm from the edge where the force would be applied. I put an egg inside a Ziploc bag to keep the gel clean when the egg broke, and put it into the hole in the gel. I cut a small piece off of the cylinder of gel to make room for the egg and put it back to that the egg was completely encased in the block. (See Figure 3.)
Figure 3. Ballistics gel with egg enclosed.
I then put the block into a large plastic container and filled in the area around it with towels and blankets. These would help to keep the block in place while not keeping it from expanding and changing shape on impact. They also helped catch the weight after it bounces off the gel to keep it from getting damaged. (see Figure 4.)
Figure 4. Plastic tub holding ballistics gel.
I put a piece of tape on the wall and marked out 2meters in 10centimeter intervals. I dropped the kettle bell from varying heights onto the gel to see at what point the egg would consistently break. (See Figure 5.)
Figure 5. Dropping the weight on the ballistics gel.
Results
I dropped the kettle bell from various heights starting at 50cm and moving up 10cm at a time. The first egg I tested broke when the weight was dropped from a height of 120cm. however, with two more eggs tested dropping the weight from as high as 300cm, I was never able to repeat those results. The problem with dropping the weight is that simply through acceleration of gravity it can’t build up enough speed to have the kinetics energy to create a powerful enough shockwave to break the egg. It doesn’t work very well to emulate the impact of a bullet because the heavier mass moving slower actually has much less kinetic energy while also having more inertia. This means that the weight creates less of a shockwave in the gel, while causing the gel to deform more to the point that the weight simply crashes into the egg to break it. In order to break the egg with the energy wave in the gel, I will need to use a lighter mass at a higher speed that won’t reach the egg, but will still have equal kinetic energy.
Table 2. Kinetic energy from falling weights.
Just to see if it was even possible to break the egg embedded 5 cm into the gel, without penetrating the gel, I tried hitting it with a sledge hammer. I eventually was able to break the egg.
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