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Full vehicle analyses:

The following tutorial will help you complete a full vehicle analysis using Adams/CAR.

First, open Adams/CAR and change the working directory by clicking File/Select Directory from

the main toolbar. Set the working directory to a folder on the C drive just as you did in the

suspension analysis tutorial.

Next, open a full vehicle model. For this tutorial, we will be using the MDI_demo_vehicle.

Click File/Open/Assembly. The Open Assembly dialog box will appear. Double click in the text

entry area of the dialog box to open the select file navigation window. Select the

MDI_Demo_Vehicle and click “Open” in the select file window and click “OK” in the Open

Assembly window.

Warning: Remember to change your working directory before you begin this lesson. If you do not,

Adams may not work correctly. Also remember to move everything you wish to keep from the working

directory before you log off. See the Opening Files tutorial for more information.

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The message window will appear and the assembly will open. Once the assembly is fully loaded,

close the message window and the open assembly dialog box. Your screen should show the

demo vehicle like the following screen shot.

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Now that we have a full vehicle model opened, we can perform a full vehicle analysis on it.

There are many different types of full vehicle analyses we can perform on our model. We can

simulate straight line acceleration and braking, constant radius cornering, lane changes, and

drifting. This exercise will simulate constant radius cornering at the vehicle’s lateral acceleration

limits. Consult the help files for a description of the full vehicle analyses Adams/CAR has to

offer. They are accessible by clicking Help/MSC.Adams help form the main toolbar.

This simulation can be very useful in comparing two different suspension setups. This

simulation can be completed for both suspension designs. The maximum lateral accelerations

can be compared, along with other parameters calculated by Adams/CAR. The comparison can

help determine which design outperforms the other in a constant radius cornering test. The

simulation will not be useful in predicting the maximum lateral acceleration of your vehicle

model unless all of the vehicle’s systems are modeled accurately. This is why a comparative

analysis will be more useful than an absolute analysis. This same procedure can be completed for

all other full vehicle analyses to determine the strengths and weaknesses of each design relative

to one another. Braking, jumping, and acceleration simulations can help to estimate forces in

components such as control arms and spherical joints so these parts can be designed to withstand

the forces they are likely to see.

First, we will complete a constant radius cornering analysis. To do this, click

Simulate/Full Vehicle Analysis/Cornering Events/Constant Radius Cornering from the main

toolbar. See the image below.

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This will open the Constant Radius Cornering dialog box. Enter the parameters according to the

picture below. This will simulate the car driving around a circular track with a radius of 100 feet.

The car will begin its travel at 20 mph and end at 50 mph. The car is not limited to travelling

only on the track. If the car cannot handle the lateral acceleration of the maneuver, it may spin

out of control or just overshoot the turns.

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After you have entered all of the above parameters, click “Apply”

The message window will appear and the simulation will begin. Once the simulation completes,

close the message window and the constant radius cornering dialog box. Zoom out on the screen

until you can see the entire track. Click review/Animation Controls on the main toolbar. This

will allow you to play an animation of the simulation. Play the simulation to see how the vehicle

traverses the 100 foot radius track.

The car overshoots the track and pushes off of the outside edge of the circular track. This is an

oversteer maneuver. This will be a good evaluative simulation to compare different suspension

setups.

Now, we will open the postprocessing window and plot lateral acceleration versus time. This will

give us an idea of the road holding capabilities for this vehicle.

Click “Review/Postprocessing window” from the main toolbar. The postprocessing window will

open. It should look like the following screenshot:

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Now, in the postprocessing window, highlight the following:

Simulation – demo_CRC_test_crc

Filter – User Defined

Request – Chassis Accelerations

Component – Lateral

Now click the “Add Curves” button. You should get a plot like the following:

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This indicates that the peak lateral acceleration of our vehicle was about 0.95 G’s before it

pushed off of the track.

For an evaluation of designs, you could change the suspension setup of this vehicle, re-run this

simulation, and then compare this lateral acceleration plot to see if you improved the road

holding ability of your vehicle.

Now, add your name and the date to this plot by clicking the “A” button on the top toolbar (see

green arrow above) and make a print of the plot.

Warning: Remember to change your working directory before you begin this lesson. If you do not,

Adams may not work correctly. Also remember to move everything you wish to keep from the working

directory before you log off. See the Opening Files tutorial for more information.