A common trait among all hyperelastic materials is that all the work done in deforming them is fully recovered upon unloading. If you have ever played with a slingshot, when you stretch the rubber band and release it, all the work done is stored as internal energy in the rubber. Upon release, it changes most of its form to kinetic energy. If the slingshot were made of, say, a copper wire, then it might sustain some plastic deformation and, in the process, spend some of the work done in the stretching process. The reduction in internal energy, in this case, would result in the projectile not moving as fast as in case of the rubber slingshot.
In this lesson, we will discuss how to use this trait to represent hyperelastic behavior using mathematical equations. We will also talk about various material models to show how the hyperelastic models are formulated.
Here are the accompanying handout slides for this lesson.