Example 1: the vehicle driveline

In order to illustrate how to use the Activity Index facility in Simcenter Amesim, follow the procedure below:

Procedure

1. Open the model named Driveline.ame from the demo area in the Tutorials directory.

Figure 30: Choose Demo dialog box

You will need to adjust the default values. Do not forget to reset the angle in MECMAS21 to –10 degrees. The necessary parameters are shown below. Figure 31: Vehicle driveline model

2. Set parameters for the submodels as shown in the following table:

Submodel name and type

Belongs to category

Main Simulation parameters

PROPERTY DEFINITION

MECRL01 (3)

      Mechanical

shaft speed port 2 [rev/min] = 2500

moment of inertia [kgm**2] = 0.2

Coefficient of viscous friction [Nm/(rev/min)] = 0

MECRL01 (4)

      Mechanical

moment of inertia [kgm**2] = 0.001

Coefficient of viscous friction [NM/(rev/min)] = 0

RN001

      Mechanical

gear ratio = 3.0

UD00

      Signal, Control

number of stages = 3

duration of stage 1 [s] = 0.1

output at end of stage 2 = 200

duration of stage 2 [s] = 2

output at start of stage 3 = 200

output at end of stage 3 = 200

UDA1

      Signal, Control

name of ASCII file: Use the browser button and locate your clutch.data file.

MECFR2R0A

      Mechanical

option 1: maximum Coulomb (dynamic) friction torque [Nm] = 400

RSD00

      Mechanical

stiffness [Nm/degree] = 200

damper rating [Nm/(rev/min)] = 1

CONS0

      Signal, Control

Constant value = 0.1

MECMAS21

      Mechanical

mass [kg] = 1000

inclination (+90 port 1 lowest, -90 port 1 highest) [degree] = -10

3. Run a simulation for ten seconds and double-click on the mass.

The dialog box below appears: Figure 32: Variable list of the mass

During this simulation the activity computation in submodels was turned off. We must now enable these calculations.

4. Open the Run Parameters dialog box and select the Standard options tab. In the Dynamic run options area, put a tick mark in the Activity calculations check box.

Figure 33: Dynamic run options

5. Click on OK, recompile the model and restart the simulation.

6. Double-click on the mass again, the dialog box below appears:

Figure 34: New values with activity index calculations

Note As you can see, two new variables are displayed at the end of the list in the power, energy, activity energy management variables folder. You will find similar activity variables if you click on most other mechanical submodels. Some submodels have no energy exchange and hence do not have activity variables. Examples of these are the ideal sensors.

Note

  Power calculations and Energy calculations are described in their respective manuals.

You can plot these variables but you can also get a list of them in a single dialog box as explained below.

7. Select the Simulate

   Power, energy, activity menu item.

This produces the following dialog box: Activity Index List dialog box

Figure 35: Activity Index List dialog box Power, Energy, Activity dialog box

On the Activity tab, you will see the list of all the activity variables defined in the model. Each one is associated with a given submodel and is either a dissipation, an inertia or a capacitance. In this dialog box, note the following facilities:

Time: indicates the simulation time for the values displayed.

Update and Automatic update: for a long simulation, you can use these to refresh the current time and the values of the activity variables, either manually or automatically.

Sum: if you select one or several lines in the list, the sum of the selected activity indexes will be displayed as in the example below Figure 36: Sum of the activity indexes

Format: the value of the activity variables can be displayed either in fixed or in floating format. The sum of the indexes, if displayed also responds to this format. Figure 37: Two formats for activity indexes

You can perform various actions. If you click on a title at the top of any column, the list will be sorted according to the selected column. This means, for example that you can sort the activities by physical, type (R, C, I, S and RS) but the most useful sort is by index so that we can see the energy active and energy passive items. Figure 38: List sorted by type

You can create special plots. If you select one or several items in the list, the Plot button becomes available. If you click on it, you will get a graphical representation of the selected activity indexes.

8. Sort the list by clicking on the Index column title and plot the two most active items. Note that these are the linear inertia of the car and the rotary inertia of the engine. This seems very reasonable.

Figure 39: Plot of the two most active items

9. Next select the three smallest activities and plot them. Together they account for about 0.04% of the activity.

Figure 40: Plot of the three smallest activities

Looking at these values, we can see that dissipation in both RL01 submodels is so small that we could use RL02 (rotary load without friction) instead.