Following a course in dynamical systems I am studying a mass spring damper system. In the particular case it is a cart constrained to a fixed point by a spring whose oscillation is damped by a damper b.
If I understand correctly the resulting position graph is the following (and input):
My question is: why is there an oscillation in the forced response (when applying force i don't know if it's the correct translation) instead of an asymptotic approach to the equilibrium value? That is, if a cart is pulled with a constant force for a given time window, the cart would not reach its maximum distance (i.e. the maximum extension of the spring for the determined force applied) gradually and without oscillations (without go back and forth)? Shouldn't his trend be as follows?
I understand it could be an ideal case in which the spring has infinite extension, but at a constant input (for infinite time) at some point does the force of the spring equals the force of the input( $F_k=u$ )? Again, there would not still be an asymptotic approach to the maximum position (without oscillation) until the spring would be released?
What am I doing wrong?
P.S. I hope I was clear, it's my first post here and English is not my native language.