Shock Absorber

The Shock Absorber is a damper entity designed to dissipate the energy stored in the suspension springs and damp the chassis motion.

The Shock Absorber force can be linear or non-linear reading the force versus velocity data from a table stored in a TeimOrbit format property file.

Parameters

Damper Type: The Shock Absorber can be a linear or non-linear type. When linear is selected, it enables the Damping Constant option and when non-linear is selected, it enables the Property File option.
Damping Constant: Damping constant value used when Shock Absorber is a linear type.
Property File: Shock Absorber properties stored in a TeimOrbit format property file containing a table of the force versus velocity.
Use Rebound Stop: Includes a Rebound Stop entity to limit the Shock Absorber component in rebound. The rebound stop is connected to the same bodies and points defined in the Shock Absorber. For more information, refer to the Rebound Stop documentation.
Use Bump Stop: Includes a Bump Stop entity to limit Shock Absorber component in jounce. The bump stop is connected to the same bodies and points defined in the Shock Absorber. For more information, refer to the Bump Stop documentation.
Scale: The scale options enable the scaling of the force and spring height without the need to directly modify the property file.
Graphics: Two cylinder graphics represent the Shock Absorber rod and tube in MotionView. This parameter allows you to modify the Rod and Tube radius for the visualization purposes.

Connecting a Shock Absorber

The Shock Absorber exerts a force along a line between two bodies and two points. When adding a Shock Absorber, the guidebar appears showing the body and points collectors, it also shows the Create Pair option to allow the creation of single or pair entities.

1. From the guidebar, select the first body to connect.
- Click Body 1 and select a body from the modeling window.
  OR
- Click the Body 1 Advanced Selector and select the required body from the dialog.
Similarly, select the second body to connect by clicking the Body 2 input collector.
Select a point and enter the location where the Shock Absorber connects to Body 1.
- Click Point on Body 1 and select a point from the modeling window.
  OR
- Click the Point on Body 1 Advanced Selector and select the required point from the dialog.
Similarly, select the second point by clicking the Point 2 on Body 2 input collector.
Open the Shock Absorber Entity Editor to edit the parameters.

Figure 1. Shock Absorber connectivity

Property File for Shock Absorber

The Shock Absorber properties are stored in a TeimOrbit format property file. When the model is submitted to the solver, MotionSolve reads the property file for use during the simulation. If the units specified in property file differ from the model units, the solver converts the air spring properties to model units, however it leaves the property file unchanged.

The Shock Absorber property file contains header, units, and curve blocks. The units block specifies the length, mass, force, time, and angle units employed in the file. The curve block holds a table of velocity against force values for the damping force component, the data should be in ascending order.

An example of the Shock Absorber property file is shown below:

$----------------------------------------------------------- HEADER
[HEADER]
 FILE_TYPE     	=  'dpr'
 FILE_VERSION  	=  4.0
 FILE_FORMAT   	=  'ASCII'
$---------------------------------------------------------------------UNITS
[UNITS]
LENGTH 	=  'mm'
ANGLE  	=  'degrees'
FORCE  	=  'newton'
MASS   	=  'kg'
TIME    	=  'second'
$---------------------------------------------------------------------CURVE
[CURVE]
{ vel    force}
 -4916.935 	-8.889
-1000.0   	-3.0
 -500.0   	-1.5
 -250.0   	-0.75
 -100.0   	-0.3
 0.0        	0.0
 100.0    	0.3
 250.0    	0.75
 500.0    	1.5
 1000.0    	3.0
 4914.298  	9.0416

Outputs

The Shock Absorber outputs channels in the MotionSolve .plt and .abf files are summarized in the table below.

The length and rate-of-change-of-length are measured along the line between Point 1 and Point 2. The damper force also acts along the same line, a positive force acts to repel the bodies, while a negative force acts to attract the bodies.

Type	Component	Quantity
User Defined (.plt) REQSUB (.abf)	ShockAbsorber - Damper Output	Length
		Rate of change of length
		Damper force
		Direction Cosine - X
		Direction Cosine - Y
		Direction Cosine - Z