General

The General option in the tree browser provides basic details and displays the entire model in the Help section. It is necessary for all the property files.



Figure 1. General Panel Section
The information that has to be entered in the Inputs and Units tabs are explained below.

Inputs

Interpolation Scheme
Defines the type of interpolation the you need for the leaf profile.
For example, if you enter the leaf shape as 40 points, and opt to generate 10 beams on the front and 10 beams on the rear, the total number of profile points required is 22. A function is needed to generate those points, but that function requires an order and interpolation schemes.
Depending on the number of points, the interpolation scheme is predicted.
  • Large number of points: Linear
  • Two starting points: Quadratic
  • Three starting points: Cubic
Data Shape Condition
The Leaf Spring Builder builds leaf springs from two different kinds of profile inputs or shape conditions.
  • Free Shape Condition: In Free Shape condition, you can generate a design, loaded in the leaf spring pack. In other words, you have a bolted leaf pack and intend to push it with design load. The leaf pack will be generated with a bolt (fixed joint) and a design load. The input profiles for this option will be the profiles as extracted from a bolted leaf stack. A Free Shape condition is when the leaves’ shapes are extracted from an assembled, but unloaded leaf pack.
    Note: The leaf pack is in an assembled condition but is NOT installed in a vehicle.


    Figure 2. Spring in Free Position
  • Pre-Assembly: In Pre-assembly, you have individual leaf profiles for each leaf in its free shape. These individual leaf profiles can be bolted together first, followed by applying a certain design load in a sequential simulation. The following image shows that all the leaves are separated and should be bolted together. Hence, if you have a free shape of each leaf, you can use this option and enter the data accordingly.


    Figure 3. Spring in Pre-assembly Position

Leaf Spring Shape Measurements

The Leaf Spring Builder creates MotionView MDL leaf-spring models which are only as good as the leaf shapes you input. Therefore it is important to accurately measure the leaf shapes in the required coordinate system. The coordinate system, its origin and orientation, needs to follow certain rules to be useful in creating a leaf-spring from the Leaf Spring Builder.
The following sections describe the coordinate systems and measurement methods for the Free and Pre-Assembly Shape conditions:
Measuring a Leaf Spring in Free Shape
In Free Shape, the leaves are already assembled into a pack, but not installed in the vehicle. Hence, all of the leaves together form a single unit. In this condition, the measurements need to be made in a consistent coordinate system. Also, it is necessary to input a correct Leaf Reference Location under the Axle tab. The Leaf Reference Marker will be created at this location.


Figure 4. Leaf Reference Location in Axle Component Properties
The following set of illustrations show the acceptable and unacceptable selections of coordinate systems, its origins and orientations for leaf shapes.
Acceptable Selections: Underslung Spring


Figure 5. Leaf Reference Location in Underslung-1


Figure 6. Leaf Reference Location in Underslung-2
Acceptable Selections: Overslung Axle


Figure 7. Leaf Reference Location in Overslung-1


Figure 8. Leaf Reference Location in Overslung-2
Unacceptable Selections:


Figure 9. Unacceptable selection-1


Figure 10. Unacceptable selection-2


Figure 11. Unacceptable selection-3


Figure 12. Unacceptable selection-4

Measuring a Leaf Spring in Pre-Assembly Shape

Leaves in the Pre-Assembly Shape condition are measured as independent entities. A common coordinate system needs to be chosen for all the leaves. The Leaf Builder takes an additional input called Bolt Location in the Pre-Assembly Shape condition, which is used to line up the leaves along a common vertical axis before they are bolted together in a MotionSolve simulation to create the assembled leaf pack.


Figure 13. Bolt Location in Leaf Details
The following set of illustrations show acceptable and unacceptable selections of coordinate systems, its origins and orientations of leaf shapes.
Acceptable Selections:
The bolt hole axis of each leaf must be parallel to every other leaf and he z-axis. The vertical locations of each leaf will be offset by MotionSolve during assembly, such that there is no contact between leaves.


Figure 14. Acceptable Selection for Pre-Assembly-1


Figure 15. Acceptable Selection for Pre-Assembly-2


Figure 16. Acceptable Selection for Pre-Assembly-3
Unacceptable Selection:


Figure 17. Unacceptable Selection for Pre-Assembly-1

Leaf Reference Marker

The Leaf Reference Marker (henceforth referred to as LRM in this section) is the coordinate system in which all the points of the leaf profiles are created in MotionView. To move/orient a leaf spring, you can simply move and/or reorient the LRM.
It is necessary during measurement to have all the leaves positioned such that the tangents at the leaf centers (clamped portion of the leaves) are parallel. A visual inspection of leaf positions on the measuring table is done to ensure this is generally sufficient to get a good leaf spring out of the Leaf Builder.


Figure 18. Leaf Reference Marker Location
The Leaf Reference Marker is created at one of the following locations based on shape condition:
  • Free Shape: Leaf Reference Location as input by the user, top leaf center for underslung spring and bottom leaf center for overslung spring.
  • Pre-Assembly Shape: Top leaf bolt location for underslung spring and bottom leaf bolt location for overslung spring.

The Leaf Builder uses the Leaf Reference Marker-origin (location) as the point where the Axle is attached.

General Inputs for Leaf Property File (*lpf)

In the General Inputs block of a Leaf Property file, the attribute, type, and valid value to be entered in TiemOrbit file format are displayed. This table also provides information about the mandatory requirements for attributes. An example of how a General Inputs block is represented in a TiemOrbit file format is shown below:
$---------------------------------------GENERAL_INPUTS
[GENERAL_INPUTS]
CURVEFITTING = 'LINEAR'
DIRECTORY = 'C:\USERS\NG\DESKTOP'
DISPMSOLVEWINDOW = 'TRUE'
NOOFLEAVES = 4.0
NOOFREBOUNDCLIP = 0.0
OUTPUTFILELABEL = 'TEST_LEAF_1'
SHAPECONDITION = 'DESIGN'
Table 1. Block Name = GENERAL_INPUTS (Required)
Attributes Type Valid Value Required
Directory String Directory path Yes
noOfLeaves Integer 1, 2, 3... Yes
curveFitting String Linear

Quadratic

Cubic

 Yes
noOfReboundclip Integer 1, 2, 3...

If there are none, then “ZERO” has to be mentioned.

 Yes
shapeCondition String 'FREE'

'PRE_ASSEMBLY'

 Yes
outputFileLabel String File_label Yes
frictionSwitch String 'On', 'OFF' Optional
dispMsolveWindow String 'TRUE, 'FALSE'' Yes

Units

Units are required for all types of the data files to be read by the builder. It specifies the length, mass, force, angle, and time units employed in the file.


Figure 19. General - Units Tab

Units for Leaf Property File (*lpf)

In the units block of Leaf Property file, the dimension, options, and conversion factors to SI used are displayed. An example of how a Units block is represented in a TiemOrbit file format is shown below.
$---------------------------------------------------------UNITS
[UNITS]
(BASE)
{LENGTH	   FORCE       ANGLE       MASS         TIME}
MILLIMETER	NEWTON      RADIAN      KILOGRAM     SECOND