6. Our advice

Just think in terms of the intervals you're interested in, and limit them. For example, if you compare the deformation of rubber with that of a spring to which the same type of stress has been applied, avoid discussing what will happen around the breaking point. The behavior of these two elements around their breaking points will most likely diverge.

This is all the more true when you have to pass on the results of your comparisons and reasoning to others. What may seem obvious to you may not be so to someone who has not participated in the elaboration of your theory.

It is therefore not impossible to have two different models, depending on whether, for example, you want to compare the shape recovery of a material after light, alternating stresses, or permanent deformation after years of stress. All you need to do is be precise in defining...