Simscape Multibody Model with Elastic tooth mesh

Question

Thomas Scheu 2024-9-16，8:48

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https://ww2.mathworks.cn/matlabcentral/answers/2153005-simscape-multibody-model-with-elastic-tooth-mesh

回答： Thomas Scheu 2024-9-17，14:06

Hi everybody,

I want to simulate an elastic tooth mesh within my simscape multibody model. The model is very simple and consists only two gears. The model works fine with the "Common Gear Constraint" block, but I want to simulate spring and damping effects. Therefore I added a Torsional Spring-Damper which I connected to the model via a Rotational Multibody Interface.

Error:An error occurred during simulation and the simulation was terminated

Caused by:

['Test_ElastischerZahneingriff_1/Solver Configuration']: Initial conditions solve failed to converge.

Nonlinear solver: Linear Algebra error. Failed to solve using iteration matrix.

The model may not give enough information to make it possible to solve for values of some of its variables. Specific advice is given below.

all components and nodal across variables involved

Tie variable 'Torsional_Spring_Damper.R.w' (Rotational velocity) to a definite value, for example by connecting an appropriate domain reference block.

Dependency found among topology equations. Check for missing reference node.

Is anybody out there who can help me fixing this error?

You can see the model in the pictures.

Thank's everybody for any helpful comment....

Kind regards,

Thomas

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Answer 1

Jaimin 2024-9-16，10:29

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Hi Thomas Scheu,

It appears from the attached model image that the “Mechanical Rotational Reference” block is missing. Please connect it with the “Torsional Spring-Damper” block to resolve the error.

For more information on “Mechanical Rotational Reference” block please refer following MathWorks Documentation

https://www.mathworks.com/help/simscape/ref/mechanicalrotationalreference.html

I hope this will be helpful.

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Thomas Scheu 2024-9-16，15:10

Thank you very much for your help! Now the error is gone, but the physical connection between the two gears does not seem to be right (as mentioned in the answer below). Do you know anything I did wrong in connecting the to gears via the torsional spring-damper?

Kind regards

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Answer 2

Thomas Scheu 2024-9-17，14:06

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I fixed the problem by adding an additional common gear constraint. Thanks.

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Answer 3

Thomas Scheu 2024-9-16，15:08

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https://ww2.mathworks.cn/matlabcentral/answers/2153005-simscape-multibody-model-with-elastic-tooth-mesh#answer_1517390

Hi Jaimin,

thank you very much for your fast respond. With your help, the simulation now starts without the error. Thank you very much.

Now the problem is that the elastic tooth mesh seems to be physically wrong. I made a screenshot to explain the problem:

I made one gear transmission with the common gear constraint block (left gear), and one with the torsion spring damper (right gear). When I compare the rotational speeds of both gears, the one connected via the torsion spring damper seems to be totally wrong (the ratio should be 1:2 - so the speed of the left gear is rigth).

I tried many combinations of the parameters of the torsional spring-damper, but nothing could come close to accurately reflecting the transition.

Is there anything to add except the torsional spring-damper to let the system "know" the physical dependence of the two gears?