Setting Up the COMSOL Model for Cosimulation
Load the model Thermal Microactuator Simplified from the COMSOL Multiphysics Application Library.
1
If it is not already open, start a new COMSOL Desktop. From the File menu, select Application Libraries ().
2
In the Application Libraries window, choose COMSOL Multiphysics>Multiphysics>thermal_actuator_simplified and click Opens ().
Start with setting up probes in the model to evaluate the actuator tip displacement and the maximum temperature in the actuator. Further ahead, when configuring the cosimulation, you will set these as the output that is passed to Simulink during cosimulation.
3
In the Definitions toolbar click Probes , and choose Domain Point Probe .
4
In the Settings window for Domain Point Probe, under Point Selection section, in the Coordinates row set x to L.
5
Select the Snap to closest boundary checkbox.
6
In the Model Builder window, expand the Domain Point Probe 1 node, then click Point Probe Expression 1 (ppbb1).
7
In the Settings window for Point Probe Expression, in the Expression text field, type -v.
8
In the Definitions toolbar click Probes , and choose Domain Probe .
9
In the Settings window for Domain Probe, in the Variable name field, type maxTemp.
10
In the section Probe Type, select Maximum as Type.
11
In the Expression text field, type T.
Continue with adding structural damping to the Solid Mechanics interface.
12
In the Model Builder window, expand the Thermal Actuator (comp1) > Solid Mechanics (solid) node, then click Linear Elastic Material 1.
13
In the Physics toolbar, click Attributes and choose Damping.
14
In the Settings window for Damping, in both the αdM and βdK text fields enter 1e-6.
Now continue with the setup of the time-dependent study that you will use for the cosimulation.
15
In the Home toolbar, click Windows and choose Add Study .
16
In the Add Study window, find the Studies subsection.
17
In the Select Study tree, select General Studies>Time Dependent, and then click Add Study .
18
In the Settings window for Time Dependent, in the Output times text field, type range(0,1e-6,1e-4) as we assume the time unit in Simulink to be seconds.
Note: Make sure to use the same time units in COMSOL and Simulink, as there is no time unit conversion when running a cosimulation.
Continue with setting up manual scaling for the variables to avoid potential convergence problems due to the use of an on/off controller during simulation.
19
In the Settings window for Study 2, clear Generate default plots.
20
In the Model Builder right-click the Study 2 node, and select Show Default Solver .
21
Expand Solution 2 > Dependent Variables 1.
22
Select the Temperature (comp1.T) node. In the Settings window for Field, locate the Scaling section and set Method to Manual. In the Scale text field enter 300.
23
Select the Electric potential (comp1.V) node. In the Settings window for Field, locate the Scaling section and set Method to Manual. The default value already corresponds to the order of magnitude of the voltage so you do not need to change the value.
It is good practice to make sure that the model solves with the intended time interval, time steps, and input parameter range that will be used when performing the cosimulation.
24
In the Study toolbar, click Compute .
The model is now ready for cosimulation, you just need to save it with a new name.
25
From the File menu, choose Save As .
26
Browse to a suitable folder, enter the filename thermal_actuator_llsimulink.mph, and then click Save.