Simulating the system

Procedure

1. Load the system using Help > Get demo, selecting the system CamAndValve.ame.

2. In Parameter mode, set the following non-default values:

Submodel

Title

Value

CONS00

constant value

1000

CAM00

file of cam position of angular position

%AME%\tutorial\data\cam.data

1 for linear splines 2 for cubic splines

2

LSTP00A

gap or clearance with both displacements zero [mm]

1

contact stiffness [N/m]

1.0e9

contact damping [N/(m/s)]

1000

SPR000A

spring force with both displacements zero [N]

500

MECMAS21

mass [kg]

0.01

lower displacement limit [m]

0

higher displacement limit [m]

0.02

It is possible to preview the data in the file defining the cam profile by using the Simcenter Amesim Run Table Editor facility. This can be started in two ways.

In the main menu bar Tools > Table editor.

Click on the Table editor button in the main toolbar .

You can do this in any mode.

3. Start the Table Editor using one of the ways described above.

Figure 74: Table Editor

4. Click on the Open button in the Table Editor toolbar or use File > Open or Ctrl+O.

5. Browse to locate the data cam.data file in the file browser. The file is located in %AME%\tutorial\data

The new display in the Table Editor is shown below. Figure 75: cam.data file

Note The data is displayed on the left as a collection of X-Y pairs. These data values can be modified, removed and new points can be added but for the purposes of this exercise do not alter any of the data. This format is referred to in Simcenter Amesim Run nomenclature as a 1D table. The 1D table can be represented as a 2D plot which is shown in the central part of the dialog box. The layout of this central part is similar to a normal plot and there is a toolbar for initiating zooms etc. If you do not see this, select View > Graph.)

At the top of the display are a number of options for altering the characteristics of the plot. The X-values go from 0 to 360 degrees. You will go outside of this range in your simulation and you want the profile to repeat every 360 degrees which is the cyclic option. For more information, please refer to the Table Editor manual.

6. Use the toolbar buttons to set the following options and look at the corresponding plot.

Interpolation type: Linear

Out of range mode: Cyclic

7. Close the window.

We now make a few general comments on the data. The cam shaft is rotating at a constant speed of 1000 rev/min. The initial value of the angular displacement of the cam is 0 degree (default value) and at the same time the relative displacement, gap or clearance in LSTP00A is 1 mm. This means the valve will be initially fully closed with a preload on the spring of 500 N.

8. Set run parameters as follows: at 1000 rev/min we have 1000/60 or about 17 rev/s. Hence 0.2 seconds seems right for the final time, with a print interval of 0.001 seconds. Set these simulation parameters.

The objective is to plot the cam lift profile at various angles.

9. Perform a run and plot displacement of the cam follower and angular displacement of the cam modulo(360)in this order, on a single plot:

Figure 76: Cam lift profile (360°)

We note the angle is in the range 0 to 360 degrees. The displacement is so low on this scale that we do not see it. Both quantities are plotted against time. To get the cam profile, we want the displacement plotted against the angle. This is described as an X-Y plot in contrast to the normal Time-Y plot.