Infinitesimal strain

Infinitesimal strain is like when you stretch out a rubber band just a little bit. It's a very small change in the size or shape of something.

Think about a cookie dough. If you take a small piece of the dough and press down on it, it will change shape just a little bit. That's like infinitesimal strain.

When scientists talk about infinitesimal strain, they're usually talking about how materials change when they're being pulled, squeezed or twisted. Even though it's very small, when you add all those tiny changes up, you can see how something can change a lot over time.

Infinitesimal strain is important for engineers because they use it to design and build things like buildings, bridges, and airplanes. They need to make sure that the materials they use can handle all the little changes that happen over time without breaking or falling apart.