I've been researching Physical Modeling lately, and so far pretty much everything makes sense from a physical/logical perspective.
The one thing that I haven't yet found a proper explanation on is the difference in overtones between soft and hard materials. I've seen it mentioned in a few places that this stiffness is the parameter which defines the difference between metallic and nylon string on a guitar, for instance. I've also caught that one of the two directions (hard vs soft) "spreads the harmonics." But that's all I've got.
So, what are these differences in overtones for rigid materials? They seem to be more spread out, I've come to recognize metallic sounds as being rather comb like. But I'm trying to eventually write code to synthesize these sounds, and need to know some details as to the way they are spread.
Also, here's a great video in which most other aspects of physical modeling are pretty well explained, as well as the mention of more spread out overtones for harder materials (though I don't remember at what time): https://www.youtube.com/watch?v=dUcNzPhZdwk