Modelling of journal bearing

How to model simple cylindrical journal bearings in simscape, provided we have bearing reaction forces and clearnaces of bearing are known for particular speed of journal?

Answer 1

[Sanju]

In Simscape, modelling simple cylindrical journal bearings can be achieved by creating a custom component that represents the bearing. In your case, you have information about bearing reaction forces and clearances for a specific speed of the journal, which is useful for setting up the model.

Here's a general outline of how to model a simple cylindrical journal bearing in Simscape:

• Open MATLAB and Simulink:

Start MATLAB and open Simulink to begin building your simulation model.

• Create a New Model:

Create a new Simulink model if you don't already have one.

• Add Simscape Multibody Block:

To start modelling the bearing, you'll need to use the Simscape Multibody block. Add a Simscape Multibody block to your Simulink model. You can find this block in the Simulink Library Browser under "Simscape" > "Simscape Multibody."

• Define Mechanical Components:

Inside the Simscape Multibody block, define the mechanical components of your system. This includes defining the journal (rotating component) and the bearing (stationary component).

• Specify Parameters:

For the bearing, you'll need to specify parameters such as clearance and stiffness properties. The specific parameters may vary depending on the type of bearing you are modelling (e.g., hydrodynamic, plain, etc.). You might need to define parameters like:

1. Clearance (radial and axial)
2. Stiffness coefficients
3. Damping coefficients
4. Bearing geometry

• Add External Forces:

To model the reaction forces, you'll need to add external forces to the journal. These forces represent the load on the bearing and should be based on the known bearing reaction forces.

• Define Speed Profile:

You'll also need to define the speed profile for the journal bearing. You can do this using a rotational motion source (e.g., a rotational velocity source or torque source) to simulate the effect of journal rotation.

• Connect Components:

Connect the mechanical components, forces, and speed source appropriately within the Simscape Multibody block.

• Simulation Setup:

Configure the simulation settings, such as the solver type, time span, and other relevant options.

• Run the Simulation:

Run the simulation to observe the behaviour of your journal bearing system. You can visualize results and analyse the bearing's performance, such as bearing reaction forces, clearance, and other relevant data.

• Parameter Tuning and Validation:

You may need to fine-tune the parameters of your model to match the expected behaviour of the real-world journal bearing. This may involve adjusting clearances, stiffness properties, or other parameters.

• Data Analysis:

Analyse the simulation results to ensure that the bearing's behaviour matches the known characteristics for the specified speed of the journal.

You can also refer to the below document link if required,

https://www.mathworks.com/help/hydro/ref/journalbearingpressurefed.html

Hope this helps!

Thanks

[Waquar Ahmed]

Thankyou for your answer.

But how do we define bearing in simscape multibody? Journal bearing pressure fed takes input as journal displacement. How we can use it in our system?