Today is the start of our “E” section in the 31 days of STEM activities for kids series (Engineering). In this engineering activity for kids, we explore the strength of aluminum foil as a building material.
Engineering Activities for Kids: Mechanical Properties of Aluminum Foil
For this project, all you need is a sheet of aluminum foil.
Before we started the activity, I asked Monkey if she thought aluminum foil would make a good building material (She said probably not). We then discussed various ways of making the foil stronger and the different types of mechanical properties.
There are five different types of strength in any material. These are compressive, shear, tensile, torsional, and yield strength. When engineers determine what kind of material to use for a project, they have to keep the strengths of that material in mind. All materials have their own unique strengths and weakness, which means that different materials are better for different applications.
For this project, we found the mechanical properties of aluminum foil.
Tensile Strength Test
Tensile strength is how much a material can be stretched before it breaks. When we tested the foil, we found we could put a lot of pressure on the foil before it would break, giving it a 7/10 for tensile strength.
Compressive Strength Test
Compressive strength is how much pressure a material can take before it breaks. Since aluminum foil is so thin, we could not break it with compressive strength, giving it a score of 10/10 (this was a flat piece of foil. A 3D piece would obviously have less compressive strength).
Shear Strength Test
Shear strength is when pressue is applied to a material from opposite sides (kind of like it is squished in a vice grip). We found that aluminum foil compressed quite quickly, giving it a shear strength of 1/10.
Torsional Strength Test
Torsional strength is how much twisting a material can take before it will break. In our tests, aluminum foil could twist for a while before breaking, but eventually it would break under torsional strength. We gave aluminum foil a 6/10 for torsional strength.
Yield Strength Test
Yield stress is a test of how much pressure a material can take before it will permanently change. We tested this by crunching the foil into a ball and trying to smooth it out again. The foil was difficult to re-flatten, so we gave it a 3/10 for yield strength.
We also conducted one final test to see how easily foil could tear and how many layers we had to add before the foil would no longer tear. We found that we had to fold the piece of foil 10 times or more before it was difficult to tear by hand.
Monkey determined that even though aluminum foil did score well on some tests, its overall weakness would not make a good building material. She was happy her initial theory was correct.
You don’t have to conduct this test on just foil. It would also be fun to conduct other engineering activities for kids by testing the strength of a lot of household items, such as plastic wrap, LEGOs, plastic plates, wood, marshmallows, and anything else you can find.
Which material would make the best building material if you have to build something out of it?
For more homeschooling advice, visit the other posts in the 31 days of homeschooling tips for moms series.