Output of simple mass-spring system in Simscape looks like its damped, but im not using a damper. Why is so?

The system I created:

As you can see, basic and simple. Mass-spring system. No damper. This is the generated response:

(position and velocity)

My question is: Why is the amplitude decreasing? From my understanding, when there is no damping, after the initial step at 0.5 seconds, the oscilation should remain stable for infinite time, but it stops after ~2 seconds. Is there something wrong with my model or is my thinking wrong?

Parameters are as follows:

spring rate: 5000 N/m

mass: 1 kg

step:

step time: 0.5

initial value: 0

final value: 1

sample time: 0

Will greatly appreciate any help :)

Answer 1

[Anudeep Kumar]

I understand that you want to make a simple Mass spring model. The model you attached, produces desired output, and I believe the problem lies in the selection of solver configuration. Probably you are using local solver and Backward Euler, as the solver type.

The Backward Euler tends to damp out oscillations, but is more stable, especially if you increase the time step. You can either uncheck ‘Use local solver’ or use Trapezoidal Rule Solver.

For more insight on making optimum solver selection you may refer to the link:

https://in.mathworks.com/help/physmod/simscape/ug/making-optimal-solver-choices-for-physical-simulation.html