Wheels, Adjustable forces and Gears
Wheels
A wheel is a specialized part you can use when creating tire models. In Adams Car, creating a wheel corresponds to creating the metal rigid body part (the rim) and the rubber (tire) around it. You model the rim with a general rigid part and the tire with a general force (GFORCE). For information on GFORCE, see the
Adams Solver online help.
In Standard Interface, to modify a wheel:
1. Right-click a wheel, and then select Modify.
2. Press
F1 and then follow the instructions in the dialog box help for
Modify Wheel.
3. Select OK.
In Template Builder, to create or modify a wheel:
1. From the Build menu, point to Wheel, and then select New/Modify.
3. Select OK.
Adjustable Forces
An adjustable force is a special user-defined element (UDE). You can use adjustable forces for a variety of conditions, to satisfy static parameters in your model. For example, if you want to set the length of a rod to be a specific length during static analysis, the adjustable force will vary until the desired end condition is satisfied.
For example, a typical application is to use an adjustable force to set toe, camber and caster values during a static suspension analysis. You might use two parts to define the tie rod and attach them by a translational joint. You would then apply an adjustable force between the two parts to achieve the desired toe angle.
Adjustable forces act between two appropriate parts and perform a series of adjustments during static equilibrium to minimize the error between the current computed toe/camber/caster/ride height value and the desired toe/camber/caster/ride height.
After the adjustment phase is complete, the adjustable force uses either a single-component force or a motion to control the distance between the two parts. If you use the force method, you must set appropriate stiffness and damping values.
If more than one adjustable force is defined in a model, you should use the pattern statement within the adjustable force definition. The pattern statement defines the order in which adjustable forces are active. The following table defines 12 adjustable forces.
Adjustable force: | Pattern 1: | Pattern 2: | Pattern 3: |
|---|
Front left toe | 100 | 100100 | 100100100 |
Front right toe | 100 | 100100 | 100100100 |
Front left camber | 010 | 010010 | 010010010 |
Front right camber | 010 | 010010 | 010010010 |
Front left caster | 001 | 001001 | 001001001 |
Front right caster | 001 | 010001 | 010001001 |
Rear left toe | 100 | 100100 | 100100100 |
Rear right toe | 100 | 100100 | 100100100 |
Rear left camber | 010 | 010010 | 010010010 |
Rear right camber | 010 | 010010 | 010010010 |
Rear left caster | 001 | 001001 | 001001001 |
Rear right caster | 001 | 010001 | 010001001 |
In Pattern 1, three separate static analyses would be run. In the first analysis, the toe adjustable forces would be active. During the second analysis, the camber adjustable forces would be active. During the third analysis, the caster adjustable forces would be active.
In Pattern 2, six separate static analyses would be run and the same order as in Pattern 1 would be repeated. Because the camber is directly affected by the toe and caster change and vice versa so it is often desirable to build up patterns such that you can find a static solution by running a number of separate static analyses.
Pattern 3 is an example of nine separate static analyses.
The _double_wishbone_advanced template distributed in the acar_concept database contains an example of adjustable forces for toe, camber and caster.
In Standard Interface, to modify an adjustable force:
1. From the Adjust menu, select Adjustable Force.
3. Select OK.
In Template Builder, to create or modify an adjustable force:
1. From the Build menu, point to Adjustable Force, and then select New/Modify.
3. Select OK.
Gears
We provide two constraint-based gear options within the Template Builder:
■Differential gear - The differential gear applies a reduction ratio between an input joint and the symmetric output joint pair. The joint can be either revolute or cylindrical. The motion direction can be inverted between the input and output joints and a toggle exists to switch between the two different modes, allowing the reduction ratio to always be positive.
The reduction ratio is based on the following equation:
input motion = reduction ratio * (output motion1- output motion2)/2
You can define the differential gear to be kinematically active, allowing the element to be turned on or off depending on the type of analysis you are running: compliant or kinematic.
■Reduction gear - The reduction gear applies a reduction ratio between the input and output joint. Either joint type can be translational, revolute, or cylindrical. Additionally, the motion direction can be inverted between the input and output joints and a toggle exists to switch between the two different modes, allowing the reduction ratio to always be positive.
When you enter a cylindrical joint in the input or output Joint text box, an additional text box becomes active. Because either the rotational or translational degree of freedom of the cylindrical joint can be used, you must specify if the rotational or translational motion will be the output for the gear.
The reduction ratio is based on the following equation:
input motion = reduction_ratio * output motion
You can define the differential gear as being kinematically active, allowing the element to be turned on or off depending on the type of analysis you are running: compliant or kinematic.
Note: | A gear in Adams Car is a coupler in Adams View. |