DYNATUNE SUSPENSION DESIGN MODULE - THE WORKBOOK
DYNATUNE SUSPENSION DESIGN MODULE was created in 1989 in FORTRAN and a few years later rewritten in Turbo Pascal. Up to 2007 the software/calculation algorithm could not be imported into MS EXCEL due to the lack of standard MATRIX functions, which only became available in MS EXCEL/OFFICE 2007. Now today the workbook exists in its most complex variant out of 26 worksheets, when filled with results it contains a total of more than 17 million cells created with more than 22000 formula calculation cells.
DYNATUNE-XL DOES OFFER TWO VERY HELPFUL DOCUMENTS TO ENHANCE THE UNDERSTANDING OF SUSPENSION DESIGN
- THE 5 "MUST KNOW" FUNDAMENTALS OF VEHICLE SUSPENSION DESIGN
- THE 10 "EASY" STEPS TO HAPPY (ELASTO-) KINEMATICS DESIGN GUIDE
DYNATUNE-XL has developed for RELEASE 8.1 of the SUSPENSION DESIGN MODULE in the "Expert" Version a truly Unique Optimizer for Kinematic and Elasto-Kinematic Suspension Characteristics, allowing the user in a quasi full automatic mode - in a matter of minutes - to create the best possible Suspension Geometry and most suitable Link Stiffness (Bushing) Values for his selection of Constraints & Targets. The Optimization Method is based on the principle of a Linear Senstivity/Screening Design Of Experiments (DOE) implemented in the below shown Optimization Process.
DYNATUNE SUSPENSION DESIGN MODULE - USER INTERFACE - OPTIMIZER INPUT DATA
Prior to going into all details of the Features of the SUSPENSION DESIGN MODULE one can find here a brief overview of the Interface of the Elasto-Kinematic Optimization Feature with the most important Informations.
Based on a "Sensitivity Study" for each X-, Y-, & Z-Coordinate and Stiffness in the Suspension System, the Optimization procedure will focus on minimizing the Difference between Actual Performance and Target Performance by a propietary DYNATUNE-XL Cost Function, The Suspension Performance Index.
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The User can fully control the Constraints for the Optimization Exercise. Each Coordinate of the Suspension Link Joints can be on-request (De-) Activated (to consider for example important packaging constraints).
The User can also define the amount of change to the Participating Factor in the Sensitivity Study. |
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The Design Space / Operating Range for the Optimization Process (entirely executed with the standard MS EXCEL SOLVER ADD-IN) can be entirely customized to the specific requirements of the User.
The User can Select out of 3 Levels of "Optimization Involvement" :
- Control and Execute Each Step of the Optimization Process Manually
- Partially Control The Process
- Execute Quasi Fully Automatic Optimization Loop(s)
All three Levels are displayed in the Flow Chart below as Red, Amber & Green and as such indicating what should be the preferred User Selection.
DYNATUNE SUSPENSION DESIGN MODULE - USER INTERFACE - SUSPENSION INPUT DATA
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Primary Input Data for Calculation are the Coordinates of the Wheel, the 10 attachment points of the 5 Links and the 2 Coordinates of the Spring/Damper Unit. These coordinates can be entered either in the proprietary DSDM Coordinate System or a typical OEM Coordinate System with consequent coordinate transformation into DSDM sign conventions.
Additionally some specific setup & car data like STATIC TOE, CAMBER and STATIC LOADED RADIUS must be entered together with the maximum Spring/Damper Displacements in Jounce/Rebound Travel or in the case of a "steerable" suspension maximum Steering Rack Travel can be entered. Calculation Modes are:
In RELEASE 8.0 a Steering Motions & Combined Jounce & Steering Motions can be executed with the Spring/Damper Unit (or Push-Rod) attached to the Upright. |
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DYNATUNE SUSPENSION DESIGN MODULE - BASE GEOMETRIES
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.DYNATUNE SUSPENSION DESIGN MODULE comes with 3 Standard Base Suspension Templates which allow to create 99% of the nowadays most commonly used suspension architectures. The Tool provides all necessary means to investigate the kinematics of those suspensions.
Optionally one can display Link Identification Labels. This will help Novice Users to understand the selected Suspension Architecture better.
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DYNATUNE SUSPENSION DESIGN MODULE - USER INTERFACE - Animation FEATURE
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DYNATUNE SUSPENSION DESIGN MODULE comes with a Corner Suspension View/Animation Window which does permit to check model layout during the data input phase and allows to see the animation of a Jounce and Steering Motion (or if calculated, the combined motion of them as they would occur on the car). Animation can be executed with or without Data-Labels activated. For maximum user convenience the View/Animation Window can be set to 7 Pre-Set Views or can be rotated around every reference axis by entering a custom rotation angle. The View/Animation Window can be scaled to zoom and the animation "frame" rate can be set manually, which is especially convenient for Suspension Designs optimized for large wheel travels - typically seen on Rally Cars or Heavy Duty Off-Highway Vehicles. Tire Width can be adapted solely for Graphic Rendering. |
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DYNATUNE SUSPENSION DESIGN MODULE - USER INTERFACE - POST PROCESSING
TABULAR RESULTS:
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As mentioned before the post processing in DYNATUNE SUSPENSION DESIGN MODULE is entirely based on applied vector algebra. This implies that all results are derived only from the 3 dimensional movement of the Upright/Knuckle. This fact allows correct calculation of all suspension parameters even for complex suspensions with a virtual steering axis.
For quick reference and model verification one can check the most important suspension and steering system parameters in a small table. This table can be manually updated for various Wheel Positions. |
In case of using specific Rocker Linkages the tabular RESULTS output table does contain all important data & characteristics of the Push-/Pull-Rod, Rocker and Anti-Roll Bar Linkage. Next to classical translational motion ratio's for coil spring systems also angular motion ratio's and deflection angles are calculated in order to lay-out systems based on torsion springs in the Rocker axis.
On the RESULTS Sheet one can find far more characteristics, all listed as a function of Wheel Travel or Steering Angle.
On the RESULTS Sheet one can find far more characteristics, all listed as a function of Wheel Travel or Steering Angle.
GRAPHIC RESULTS:
For detailed analysis a range of 28 Pre-Set Graphs is available. The Graphs can be conveniently enlarged to a custom set value and allow confronting up to 5 variants at once. The Graphs are arranged according their typical use to either Jounce/Roll Motion or Steering Motion Results:
For detailed analysis a range of 28 Pre-Set Graphs is available. The Graphs can be conveniently enlarged to a custom set value and allow confronting up to 5 variants at once. The Graphs are arranged according their typical use to either Jounce/Roll Motion or Steering Motion Results:
Jounce/Roll Motion Results: Steering Motion Results:
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DYNATUNE SUSPENSION DESIGN MODULE - USER INTERFACE - DATA MANAGEMENT
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All calculation Results are being stored in a freely customizable RESULTS Sheet. The RESULTS Sheet contains more than 50 different data columns of Suspension Parameters and contains also all the Graphs that are available on the User Interface for further custom Post-Processing on the sheet.
. For convenience up to 4 Calculation Results Data Sets can be stored together with the input data into 4 Reference Sheets for Comparison and eventual future Re-Loading/Re-Calculation. Last but not least one can export the Suspension Model Data Set into an external MS EXCEL File which does allow effective Data Management and does provide a convenient way to transfer the input data from one license to another license of DYNATUNE SDM or create a special data set for importing Suspension Data into DYNATUNE R&H. |
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DYNATUNE SUSPENSION DESIGN MODULE - RACE GEOMETRIES
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In the "RACE" & "EXPERT" Version of DSDM a Push-/Pull-Rod Rocker System has been superimposed on the Standard Suspension Architectures. These Rocker Systems can be selected to be with or without a Anti-Roll Bar Linkage. The Anti-Roll Bar Linkage itself can be configured to be either a U-Bar or T-Bar configuration. 
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DYNATUNE SUSPENSION DESIGN MODULE - USER INTERFACE - RACE SUSPENSION INPUT DATA
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Primary input data for Push-/ Pull-Rod, Rocker and Anti-Roll Bar Linkage are the coordinates of the various attachment points. These coordinates can either be entered in the proprietary DSDM Coordinate System or in a typical OEM Coordinate System with consequent coordinate transformation into DSDM sign conventions.
Based on the selected Rocker Configuration Template the input table will be dynamically adjusted. |
GRAPHIC RESULTS:
For detailed analysis of the Rocker System a range of 12 additional Pre-Set Graphs is available. The Graphs can also be conveniently enlarged to a custom set value and allow confronting up to 5 variants at once. The Graphs are arranged according their typical use to in Jounce/Roll Motion.
For detailed analysis of the Rocker System a range of 12 additional Pre-Set Graphs is available. The Graphs can also be conveniently enlarged to a custom set value and allow confronting up to 5 variants at once. The Graphs are arranged according their typical use to in Jounce/Roll Motion.
DYNATUNE SUSPENSION DESIGN MODULE - SUSPENSION COMPLIANCE
The Key Feature of DYNATUNE "EXPERT" SUSPENSION DESIGN MODULE is the unique possibility of adding Link Stiffness to the Geometry which allows to investigate the effects of Compliant Suspension Characteristics. By entering appropriate values in the corresponding input cells or by setting the numbers to 0 one can activate or deactivate the link compliance. This allows a detailed analysis of the influence of each link on the overall suspension performance and provides an excellent up-front design tool prior to having to revert to complex and costly multi-body-system analysis tools.
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The RESULTS for all Compliance Effects are shown in the Table below. By entering a value for Pneumatic Trail the effect of Tire Aligning Torque will be considered and when using a McPherson Strut Suspension optionally the Bending of a Damper Strut can be included.
When entering numbers Link Stiffness Values this table will be automatically calculated and present for all load applications that can apply the wheel typical geometry compliance gradients. In effect the the table summarizes for the most commonly used suspension parameters how much this parameter changes per kN of applied load. |
The Link Stiffness Value is a "Lumped Number" consisting out of various local stiffness contributors that have to be united into one single value. Below shown is the picture of the tool which is being used to add/break down the most important stiffness contributors in the overall link assembly system. By entering measured numbers or by relying on historical reference numbers a good estimate for the Total Link Stiffness can be calculated. Since all local stiffness contributors are added as "Springs in Series" the weakest component defines the final overall stiffness number dominantly.
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DYNATUNE SUSPENSION DESIGN MODULE - LOADCASE ANALYSIS
Beyond the unique Compliance Table the "EXPERT" Version does offer also a SUSPENSION LOADCASE ANALYSIS TOOL which allows to enter specific loads at the Contact Patch / Wheel Center and calculate:
With this feature an experienced Suspension Designer can quickly cross check not only the geometric performance, but also the compliant performance and the various link load paths.
- The corresponding Loads in each Suspension Link
- Toe, Camber & Caster for the applied Wheel Loads
With this feature an experienced Suspension Designer can quickly cross check not only the geometric performance, but also the compliant performance and the various link load paths.
Last but not least the "EXPERT" Version offers in RELEASE 8.0 a major update to the VEHICLE LOADCASE GENERATION TOOL which allows to create a reference table for approximate Suspension Corner Loads based on imposed vehicle accelerations in X, Y, Z direction and aerodynamic loading. A basic "R&H-Type" Vehicle Model does allow to create Vehicle Corner Loads which in a secondary step are being transformed into Suspension Link Loads. Dynamic Load Factors can be considered.
For ultimate convenience RELEASE 8.0 does contain an automatic Link Load Table Generator. Based on the selected Vehicle Loadcases one can create a table of Link Loads either for a Front Suspension or a Rear Suspension.
