What could be the reason for [DASKP] Warning when using two simulate blocks in MotionView template?

_Simon08

Hello,
I am currently trying to create a scripted simulation where a part is being held by a Fixed Joint and later released. And I have ran into some trouble.

When I run the simulation without a script it works fine both ways, meaning without a Fixed Joint that constraints my part and even when I activate my Fixed Constraint. My defined Motion Entity works and moves the model as expected.

Now when i try to script my simulation the whole thing falls apart. Even when I don't <Deactivate/> or <Activate/> any Joints/Constraints:

<Simulate
analysis_type = "Transient"
end_time = "0.002"
print_interval = "0.0001"
/>
<Simulate
analysis_type = "Transient"
end_time = "0.0025"
print_interval = "0.00001"
/>
<Stop/>

I have tried using a smaller h_max wit <Param_Transient/>, but that also doesn't work.
My Solver View continues to get spammed with this Warning: WARNING: [DASPK] The nonlinear system solver in the time integration could not converge. And after a while it tells me the code could not recover. Without the Motion Entity it runs.

When the Model is not being held by the Fixed Joint (301010) (loose), I use a Planar Joint (301000) to remove rot_x, rot_y and trans_z. Here is the complete Template I want to use:

<Deactivate
element_type = "JOINT"
element_id = "301000"
/>
<Simulate
analysis_type = "Transient"
end_time = "0.002"
print_interval = "0.0001"
/>
<Deactivate
element_type = "JOINT"
element_id = "301010"
/>
<Activate
element_type = "JOINT"
element_id = "301000"
/>
<Param_Transient
h_max="0.00001"
/>
<Simulate
analysis_type = "Transient"
end_time = "0.0025"
print_interval = "0.00001"
/>
<Stop/>

So I have:

Motion + loose not scripted: works (Here it completes the entire Model Movement as expected, but I want to hold it in Position before being pulled by a Spring entity)
Motion + fixed not scripted: works
No Motion + fixed → loose scripted: works
Motion + fixed → loose scripted: doesn't work

I do have a Constraint Loop with three Parts, each of them is connected through a Revolute Joint with each other. As I said without the Scripted Simulation it works, but could this still be the Problem? I have noticed in the log-File that a lot of constraints are being marked as redundant and are being deleted.
I unfortunately can't provide my model. I would greatly appreciate some insight and Ideas on what to check next. Maybe some of you have encountered a Problem like this before.
Thank you!

I am using MotionView Version 2026.1

GTT Adam

Hi @_Simon08,

Activating a joint mid-simulation can cause the solver to fail as the constraint is likely being activated in its design position and not its current position. Also, if a Motion is applied to a Joint that you are deactivating, you will need to deactivate the Motion first and then the Joint.

To create a Joint on the fly, you can follow this Tutorial: https://2021.help.altair.com/2021/hwdesktop/mv/topics/solvers/ms/understand_seq_sim_intro_t.htm

Essentially, you need two Templates to achieve this. The link I posted uses the old interface, but the workflow is nearly identical.

Hope this helps!

Adam Reid