Initialization failed in very simple simscape model

I made a very simple model using simscape in the attachment. But when I run it, it always says initialization failed to converge. I have tried my best to make the initial condition consistent.

Initial conditions solve failed to converge.
...Problems possible for transient initialization, as well as stepsize control for transient solve, due to equations (including nonlinear equations) of one or more components:
'simple_but_failed_initial/Translational Hard Stop'
Equation location is:
'C:/Program Files/MATLAB/R2013b/toolbox/physmod/simscape/library/m/+foundation/+mechanical/+translational/hardstop.ssc' (line 59)

'simple_but_failed_initial/Translational Spring1'
Equation locations are:
'C:/Program Files/MATLAB/R2013b/toolbox/physmod/simscape/library/m/+foundation/+mechanical/+translational/spring.ssc' (line 28)
'C:/Program Files/MATLAB/R2013b/toolbox/physmod/simscape/library/m/+foundation/+mechanical/+translational/spring.ssc' (line 29)

Here is the snapshot of the model, really simple.

Answer 1

[pietro]

have you tried to connect the damper to the ground as well?

Answer 2

[david]

I think the spring cannot be directly connected to hard stop, there will be singularity, isnt it!

David

Answer 3

[Abe]

You may have answered this by trial and error methods by now but I'll give some input in case anyone else runs into this problem as well.

You may notice that the mass/spring/reference blocks alone work as expected. To test this, you can double-click the spring block and give it an initial deformation or force (depending on MATLAB and Simscape version) to pre-load it. Use a translational sensor to measure the displacement of the mass and then run the model and view results.

After you have the above working you can use trial and error methods to find how to proprely insert the hard stop.

To properly attach the hard stop it should NOT be in series to the mass and spring as shown above. Instead attach its rod end in between the mass and spring and its case port to another trasnlational reference. Though, you could also use the reference in the model above. After this change, your model should work as expected.