7.3.3 Animating the Results
In this section, you view the analysis you just ran. ADAMS/Car has already loaded the animation and graphic files for you.
To animate the results:
1) From the Review menu, select Animation Controls.
2)
Select the Play tool
.
ADAMS/Car animates the motion of the suspension analysis. Notice that the suspension moves from rebound (down), to bump (up), and that the steering wheel does not rotate.
3) When the animation is complete, close the dialog box.
7.4 Performing a Baseline Pull Analysis
You can now perform a baseline pull analysis to study the pull on the steering wheel. You will use the results of this pull analysis as the baseline against which you compare the results of another pull analysis that you perform after you modify the location of the steering axis. By comparing the results from the two analyses, you can determine if the modifications were successful.
7.4.1 Defining a Loadcase File
Before you can run the baseline pull analysis, you need to create a loadcase file to drive the analysis. In the loadcase file, you specify the unequal braking forces to simulate braking on a split-μ surface and the beginning, or upper, and ending, or lower, steering wheel angles.
To calculate the unequal brake forces, we assume that the vehicle is braking at a rate of 0.5 g’s deceleration, with a 64% front and 36% rear brake ratio, a vehicle mass of 1,400 kg, and the front braking force split 55% left and 45% right. Based on these assumptions, the total front braking force is:
1400 kg × 0.5 g × 9.81 m/s2/g × 0.64 = 4395 N
From this, the left and right braking forces are:
■ Left braking force = 0.55 × 4395 N or 2417 N
■ Right braking force = 4395 N - 2417 N or 1978 N
You can use these calculations to define the loadcase file.
To define a loadcase file:
1) From the Simulate menu, point to Suspension Analysis, and then select Create Loadcase.
Note: If Select Loadcase Type is not set to Static Load, your dialog box will look slightly different. Make sure you select Static Load first, and then proceed to fill in the dialog box.
2) Fill in the dialog box as shown next, and then select OK.
ADAMS/Car creates the loadcase file, named brake_pull.ldf, and stores it in your private database. It stores the loadcase file as text (ASCII) and you can print it or edit it manually.
To create the loadcase file, ADAMS/Car takes the parameters that you entered and generates a table of input values. For the parameters that you entered, ADAMS/Car generates a table that varies steering wheel angle from -180 to 180 in 15 steps, while holding the braking forces constant.
Table 7.1 shows the loadcase file values:
Table 7.1 Loadcase File for Pull Analysis
Steering Wheel |
Left Brake Force |
Right Brake Force |
-180 |
2417 |
1978 |
-156 |
2417 |
1978 |
-132 |
2417 |
1978 |
-108 |
2417 |
1978 |
-84 |
2417 |
1978 |
-60 |
2417 |
1978 |
-36 |
2417 |
1978 |
-12 |
2417 |
1978 |
12 |
2417 |
1978 |
36 |
2417 |
1978 |
60 |
2417 |
1978 |
84 |
2417 |
1978 |
108 |
2417 |
1978 |
132 |
2417 |
1978 |
156 |
2417 |
1978 |
180 |
2417 |
1978 |