Node/Code/Technic/Trick/Hack/... to detect bend surfaces?


sorry…I am not native speaker…the subject to this post may lead to some misunderstanding…

Let me explain:
What I am looking for is an animation-safe way to detect parts of an object which are not plane. I am not looking for a stress-map, which detects plane parts of an object, which get bend in the process of animation.
Furthermore the method should detect, whether the bend/curved (?word?) part of the object is bend away from averaged surface normal or bend towards it.

Is it possible in some way? If yes, how?

Thank you very much in advance for any help or idea !