Suggest stiffness measurement methods.
Greetings, I do not understand your question, please provide us more details about your issue.
All the best
The example : stiffness of joint or the stiffness of nonlinear spring or stiffness of any material.
I see, this forum is intended to solve questions related with Ubidots, I think that you would obtain a proper answer if you post this question in an electronic forum that focuses on sensors management.
Anyway, I will let your post opened to check if any member of our community may give you any hint to reach your goal.
All the best