Why is my shock absorber doesn't show the internal mechanics that I defined ?

There is a problem in my model which makes me confused, when I followe the tutorial video of Formula student physical modeling training, I defined my shock absober internal mechanics such as spring stiffness and damping coefficient. The tyre shold move a little bit under the force of gravity. However, when I run the model, the motion of the shock absorber looks like the figure below. It seems like the shock absorber internal mechanics I defined is not working. Can anyone tell me what mistake I've made? Is it the problem of my world frame ? PS: my matlab version is 2014b

Answer 1

[Swarooph]

Hello Shuo,

This is because, you have not defined the densities for the solids appropriately. Set the density of all the following solids to '8000 kg/(m^3)' so that it resembles steel.

1. Cylinder (in the Shock absorber subsystem)
2. Piston (in the Shock absorber subsystem)
3. rim (in the Wheel subsystem)

You can find this parameter in the 'Inertia' dialogue:

Your tyre solid can remain at 1200 kg/(m^3) to resemble rubber if you want (the example model probably has an 8000 kg/(m^3) for that as well and could be considered a bug). In this case, my result looks as follows:

But if you want to replicate the exact same result as in the example, set the density of the tyre also to 8000 kg/(m^3).

[Shuo Wang]

Hello, dear sir. Thanks for answering my qusestion. However, there is still one thing I dont understand in the video. It said we need to create a contact point with the rigid transform block, however, I find that you rotate the follwer frame with respect to the base frame, does this contain any special meaning ? Is there anything I need to care when I create a contact point ?

[Swarooph]

I have answered this in the other post you have created.