Rear SLA (1pc LCA)
A Short-Long Arm (SLA) suspension is included in the vehicle library as both a front and rear suspension. This configuration is also known as a Double Wishbone suspension. The coil spring and the shock absorber typically connect to the lower control arm. The SLA name is derived from the length of the control arms. The lower arm is typically long to provide a good spring lever ratio. The upper arm is typically short to provide the proper camber curve. This suspension is widely used on cars, light trucks, and on independent suspension heavy trucks.
- The wheel is connected to the wheel hub with a fixed joint.
- The wheel hub is connected to the knuckle with a revolute joint.
- The knuckle is connected to the upper control arm (UCA) and lower control arm (LCA) with a spherical joint.
- The upper control arm and lower control arm is connected to a sub frame or the chassis with two bushings.
- The lower control arm is modeled as a single rigid body (1pc LCA).
- The suspension in the library is symmetric.
Model Use
- The wheel body represents the mass of the tire and the rim.
- The wheel hub body represents the mass of the wheel hub and any other components that rotate with the hub, such as a brake rotor. There are no graphic entities for the wheel hub.
- The upper control arm bushings are defined so their axes are parallel. If the front bushing is moved, both the front and rear bushing realign so that they have the same axis of rotation. The lower control arm bushings’ rotational axes are defined in the same manner.
- Each body’s Center of Gravity (CG) is estimated from the body’s geometry. The formulas are coded into the point panel and can be seen via the graphical user interface. If more accurate CG locations are available they should be used.
- The wheel and wheel hub parts use the Wheel CG location as the center of gravity.
- When the suspension is built as a kinematic suspension, the upper control arm bushings are replaced with a single revolute joint located at the forward bushing location. The lower control arm bushings are replaced with a revolute joint in the same fashion.
- A wide variety of combinations of suspensions and subsystems can be built using the
Assembly Wizard. You are encouraged to build systems and
understand the resulting model using the graphical user interface.
When building a new suspension model, build the model with all of the optional systems (stabilizer bar, etc) included in the model. Immediately turn off the systems using the Project Browser and run an analysis on the base suspension to ensure it solves properly. As data becomes available for the optional systems; activate those systems and populate them with data.
Attachments
Entity | Attaches To |
---|---|
Lower Control Arm | Default: Sub-frame No subframe: Vehicle body No vehicle body: Ground |
Upper Control Arm | Default: Sub-frame No subframe: Vehicle body No vehicle body: Ground |
Toe Link Note: The toe link is only found when the SLA suspension is on the
rear.
|
Default: Rear Sub-frame No subframe: Vehicle body No vehicle body: Ground |
Points
Bodies
- The wheel hub body has no associated graphics and therefore is not visible in the image above.
- Only right side bodies are shown (as the left side bodies are symmetrical), and the coil spring has been omitted from the image above for clarity.
Bushings and Joints
Label | Type | Body 1 | Body 2 | Point | Notes |
---|---|---|---|---|---|
Lower Ball Joint | Spherical | Knuckle | Lower Control Arm | Lower Ball Joint | |
Upper Ball Joint | Spherical | Knuckle | Upper Control Arm | Upper Ball Joint | |
Wheel Spindle | Revolute | Wheel Hub | Knuckle | Wheel Center | |
Wheel Hub Fix Jt |
Fixed-Joint | Wheel | Wheel Hub | Wheel Center | When Spindle compliance is set to Yes, the joint type changes to universal and a bushing is superimposed to model the wheel bearing compliance. |
LCA Front Bush | Bushing | Lower Control Arm | Subframe, Vehicle Body or Ground | LCA Front Bush | When the Compliant option is set to No, this bushing becomes a revolute joint. |
LCA Rear Bush | Bushing | Lower Control Arm | Subframe, Vehicle Body or Ground | LCA Rear Bush | When the Compliant option is set to No, this bushing is deactivated. |
UCA Front Bush | Bushing | Upper Control Arm | Subframe, Vehicle Body or Ground | UCA Front Bush | When the Compliant option is set to No, this bushing becomes a revolute joint. |
UCA Rear Bush | Bushing | Upper Control Arm | Subframe, Vehicle Body or Ground | UCA Rear Bush | When the Compliant option is set to No, this bushing is deactivated. |
Inner toe Link Bush | Universal Joint | Toe Link | Subframe, Vehicle Body or Ground | Inner toe Link Bush | |
Outer Toe Link Bush | Spherical Joint | Toe Link | Knuckle | Outer Toe Link Bush |
External Files
The jounce bumper curve data and the rebound bumper curve data files are stored in the vehicle library and are referred to by this model. A new file should be created and substituted for these files when actual data is available.
Similar Suspensions
Front SLA (2pc LCA)
Rear SLA (1pc LCA)
Rear SLA (2pc LCA)