Bump Stop

The Bump Stop component limits suspension travel in bump (also known as jounce). When the distance between two bodies becomes small, the Bump Stop applies a force to push the bodies apart.

The Bump Stop force can be a linear or non-linear type and is computed from the force vs displacement table stored in a TeimOrbit format property file.

For a linear Bump Stop, the elastic force component is calculated using a third order polynomial, and for a non-linear Bump Stop the elastic force component is interpolated using the Akima method.

Parameters

Property File
The Bump Stop properties are stored in a TeimOrbit format property file containing a table of the force vs displacement.
Install Method
The install method is used to determine the distance at which the Bump Stop force starts acting. There are two install methods available:
  • Impact Length
    The impact length represents the distance between the Bump Stop attachment points when the impact happens.


    Figure 1. Impact Length method

    When the distance between the Body 1 and Body 2 is less than the impact length, the Bump Stop force acts. When the Impact Length install method is used, its value is directly used to activate the Bump Stop force between the two bodies.

  • Clearance
    Using the clearance method, the Bump Stop force is activated when the distance between the Body 1 and Body 2 is less than the Bump Stop Length minus the Clearance value, that is, when the clearance reaches a value lower than zero.


    Figure 2. Clearance method
Install Distance
The install distance represents the value of the selected install method. If Impact Length method is selected, the install distance value describes the impact length value. If the clearance method is selected, the install distance describes the clearance value.
Bump Stop length
The bump stop length is the distance between the Point 1 and Point 2 defined in the modeling configuration. This parameter is not editable and is only used to demonstrate the current bump stop length before the simulation.
Scale
The scale options enable the scaling of the force and displacement without the need to directly modify the property file.
Graphics
Two cylinder graphics represents the Bump Stop in MotionView. This parameter allows modify the Cylinder One and Cylinder Two radius for the visualization purpose.

Connecting a Bump Stop

The Bump Stop exerts a force along a line between two bodies and two points which are used to calculate the impact distance. When adding a Bump Stop, 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.
  2. Similarly, select the second body to connect by clicking the Body 2 input collector.
  3. Select a point and enter the location where the spring 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.
  4. Similarly, select the second point by clicking the Point 2 on Body 2 input collector.
  5. Open the Bump Stop Entity Editor to edit the parameters.

Property File

The Bump Stop properties are stored in a in a TeimOrbit format property file. When the model is submitted to the solver, MotionSolve reads the BumpStop property file for use during simulation. If the units in the property file differ from the model units, the solver internally converts the properties to the model units, however it leaves the property file unchanged.

The Bump Stop 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 displacement against force values for the elastic force component.

An example of the Bump Stop property file is shown below:
$--------------------------------------------------------------------HEADER
[HEADER]
 FILE_TYPE     	=  'bum'
 FILE_VERSION  	=  4.0
 FILE_FORMAT   	=  'ASCII'
$---------------------------------------------------------------------UNITS
[UNITS]
LENGTH 	=  'mm'
ANGLE  	=  'degrees'
FORCE  	=  'newton'
MASS   	=  'kg'
TIME    	=  'second'
$---------------------------------------------------------------------CURVE
[CURVE]
{ disp    force}
 0.0   	0.0
 2.0   	1.0
 4.0   	2.0
 6.0   	3.0
 8.0   	4.0
10.0  	5.0
20.0  	6.0
30.0  	7.0
40.0  	8.0
50.0  	9.0

Outputs

The Bump Stop outputs channels in the MotionSolve .plt and .abf files are summarized in the table below.
Type Component Quantity
User Defined (.plt)

REQSUB (.abf)

 Bumpstop Output Distance between points
Rate of change of displacement
Bump Stop Force
Direction Cosine - X
Direction Cosine - Y
Direction Cosine - Z