How to build a screw model by simscape?

Now I want to study Stick slip effect of screw. And I don't know how kann i build this Model. First of all, i chose to use SimMechanics. But i found that, there is no friction block. Then my teacher tell that, i should use Simscape foundation library. Here there is friction block, but i think this is very difficult to achieve this motion of screw only by foundation library. So can i build a model to study stick slip effect of screw by simscape?

Answer 1

[Sebastian Castro]

It's not too bad to get a basic screw model, actually.

I think a combination of Rotational Friction (for the screw threading) and a "Wheel and Axle" block to convert the rotary motion to linear motion will give you a good start.

In addition to that, you can always grab the source code of Simscape blocks and modify them yourself with other equations/physical elements: https://www.mathworks.com/help/physmod/simscape/customization.html

- Sebastian

[Dongbo]

Thank you for your answer. I build a same model by myself, but the graph is different from yours. Could you tell me the reason?

[Sebastian Castro]

Different parameters!

I think the only thing I changed from default is the amplitude of the pulse generator. Notice that the Friction block has a breakaway force of 25N, so you need the torque pulse amplitude to be bigger than that.

Also, I think I made the pulse 50% of the period instead of the default 5%.

... anyways, the default block parameters of the Simscape blocks are probably way far off from a screw. I'd start there :)

- Sebastian

[tianxun xiu]

Great answer！

Answer 2

[Steve Miller]

You can do this in Simscape Multibody. An example on the MATLAB Central File Exchange shows you how. See the Simscape Multibody Parts Library. You can even view the example on the web before downloading it if you click on the "Examples" tab and then find the link on the left hand side for "Lead Screw with Friction".

https://www.mathworks.com/matlabcentral/fileexchange/36536-simscape-multibody-parts-library

Hope this helps, --Steve

[Dongbo Chang]

Thank you very much!