Realistic yet fast calculations

The simulation of tires remain a challenge because they behave in a complex, non-linear manner. The calculation is either very drawn out, computationally intensive, and cannot be easily incorporated into the overall model, or it provides inexact results. The simulation tool “CDTire/3D” overcomes this dilemma.

Modeling tires realistically

Manufacturers conduct virtual tests on vehicle designs long before the first car rolls off the assembly line. Simulation of the tires has remained a challenge, however. The software tool “CDTire/3D” models the wheels realistically. The software takes into account the heat that is generated during driving and how the properties of the tires change.

CDTire – Scalable Tire Model

CDTire supports engineers in almost all analysis scenarios used in modern vehicle development processes from within Multi-Body Simulation tools. Special focus on tire belt dynamics and interaction with 3D road surfaces accurately captures the vibrations in both amplitude and frequency behavior with additional capabilities in static and stationary tire behavior.

During Multi-Body Simulations, CDTire computes the spindle forces and moments acting on each wheel in the model as well as the local contact forces while driving on 3D road surfaces or advanced tire coupled test rigs.

CDTire is a physical tire model family with different physical models for belt, sidewall and tread to balance accuracy and performance for different applications. Changing the tire inflation pressure allows quick what-if studies for different inflation pressures on different tires in the model.

Examples tire modeling CDTire
© Photo ITWM

Examples tire modeling CDTire

Available Models

  • complete 3D shell based model of sidewalls and belt
  • separate modeling and parameterization of all functional layers of a modern tire
  • includes dedicated models for belt, carcass, cap plies and tread
  • same deformation capability as FEA models
  • capturing of belt/rim contact (ground out)
  • flexible rim support
  • dedicated local brush type contact model
  • full scalable in spacial discretization and functional capabilities
  • suitable to handle inflation pressure variations during application up to total pressure loss
  • temperature model and cavity model connectable
  • applicable on arbitrary 3D road surfaces
  • can be adapted to a motorcycle tire
CDTire/ 3D: Cleat run
© Photo ITWM

CDTire/ 3D: Cleat run

CDTire/ 3D: Functional layer concept
© Photo ITWM

CDTire/ 3D: Functional layer concept

CDTire/Realtime
© Photo ITWM

CDTire/Realtime

  • flexible belt model
  • scalable belt discretization
  • local brush type contact model
  • real-time capable
  • accurate in frequency range up to 150 Hzsuitable for applications on arbitrary longitudinal wavelength road surfaces such as cleats, curbs and 2D road surfaces

  • Is a temperature enhanced Magic Formula for coupling to CDTire/Thermal in advanced handling applications
  • Based on MF 6.1 containing relaxation length concept
  • Contains empirical tread model to predict contact patch shape under various driving conditions
  • Contains additional factor based formula add-ons to feature the temperature dependence
  • Standard MF parameters can be used as basis for the temperature enhancement

CDTire/Thermal
© Photo ITWM

CDTire/Thermal

  • Is a detailed thermo-dynamical model to predict temperature creation and propagation in a tire
  • Fully 3D finite volume based description
  • The resolution is scalable in all dimensionsThe meshing is done automatically based on cross-section information
  • Runs with real time factor below 0.1
  • Easy to parameterize
  • Can be coupled with CDTire/3D, CDTire/MF++ and CDTire/Realtime

CDTire/NVH
© Photo ITWM

CDTire/ NVH: Mode shape

  • Is a software toolbox to derive a linear model from CDTire/3D for a rolling preloaded tire
  • Linear tire model can be used for modal analysis and imported into NVH tools
  • Discrete local contact area excitation or alternatively global poster excitation
  • Export of A, B, C, D matrices (1st order) or M, C, K matrices (2nd order)
  • Alternatively export of transfer functions for direct usage in NVH tools

CDTire – Typical Applications

  • Ride comfort studies on digitized road surfaces
  • Harshness analysis on artificial obstacles such as cleats
  • Durability analysis to predict spindle forces while driving on a durability test track
  • NVH analysis using transient simulation in time domain or simulations in frequency domain based on linearized models
  • Steering moment analysis during parking maneuvers
  • Tire coupled test rig applications with up to all 6 directions driven for each tire
  • Handling analysis on flat and 3D roads
  • Active safety (ABS, ESP,…)
  • Safety analysis with different fourth wheel
  • Variation of inflation pressure
  • Misuse-like events including tire ground out (also with flexible rim)
  • Real-time applications like MIL / SIL / HIL

CDTire – Parameter and Parameter Identification

Parameter identification tool CDTire/PI
© Photo ITWM

Parameter identification tool CDTire/PI

To determine the model parameters of CDTire in such a way that an existing tire is adapted, tire data sets and measurements are needed that describe the physical properties of the tire.

The parameter identification tool CDTire/PI utilizes the complete process to support the identification of the best parameter set. This process includes:

  • import of the standard tire measurements from arbitrary test labs
  • setup and execution of the related tire simulations
  • automatic comparison of measurement and simulation using different measures

The tool is a stand-alone software, no additional MBS solver is needed. CDTire contains an example set of tire parameter files for a 195/65 R15 tire. Additionally, ITWM is offering CDTire parameter identification as an engineering service. This data is then compared to simulations with systematically varied parameters to identify the best parameter set.

CDTire – Road Surface Models

CDTire Surface Viewer
© Photo ITWM

CDTire Surface Viewer

CDTire – Road surface models
© Photo ITWM

CDTire – Road surface models

CDTire needs geometric road surface models that return surface positions and a road-side friction coefficient. The associated road body can be arbitrarily driven in both translational and rotational directions for accurate, more complex poster test rig applications.

The following road surface models are available:
 

RSM 1000
User defined parametric obstacles and 3D digitized test track in simple ASCII-format

RSM 1002
Rolling drum surface for 1 axle

RSM 1100
User defined road surface

RSM 2000

3D digitized test track including parametric obstacles optimized for large data sets

RSM 3000

OpenCRG format

CDTire/Legacy

  • CDTire20
  • CDTire30
  • CDTire40
  • CDTireMC (motorcycle tire model)

These models are still supported but will be discontinued in future releases.

The CDTire30 can be directly replaced by CDTire/Realtime.

The CDTire40 can be mostly adapted by CDTire/3D by switching to an immaterialized membrane-type sidewall model.

CDTireMC can be created based on CDTire/3D by realizing the motorcycle typical steel belt constructions.

System Requirements and Publications

 

 

 

Supported simulation platforms:

  • LMS Virtual.Lab Motion
  • MSC.ADAMS
  • SIMPACK
  • Altair MotionSolve
  • MATLAB & Simulink

Supported operating systems:

  • Windows (32-bit and 64-bit)
  • Linux (32-bit and 64-bit)

 

 

 

Gallrein, A., Baecker, M., Burger, M., Gizatullin, A.: An Advanced Flexible Realtime Tire Model and its Integration Into Fraunhofer's Driving Simulator, SAE Technical Paper 2014-01-0861, 2014.

Burger, M., Bäcker, M. Gallrein, A., Kleer, M.: Integration eines detaillierten, flexiblen Reifenmodells in den Fraunhofer Fahrsimulator, VDI-Berichte Nr. 2211, Reifen-Fahrwerk-Fahrbahn, 167ff, 2013.

Gallrein, A., Baecker, M., Gizatullin, A.: Structural MBD Tire Models: Closing the Gap to Structural Analysis - History and Future of Parameter Identification, SAE Technical Paper 2013-01-0630, 2013, doi:10.4271/2013-01-0630.

Gallrein, A., Bäcker, M.: Structural MBD Tire Models: Evolving from Spindle Load to Deformation Measurements, in: Proceedings of ECCOMAS Multibody Dynamics 2013.

Gallrein, A., Bäcker, M.: CDTire: State-of-the-Art Tire Models For Full Vehicle Simulation, Americas HyperWorks Technology Conference, 2012.

Baecker, M., Gallrein, A., Hack, M., Toso, A.: A Method to Combine a Tire Model with a Flexible Rim Model in a Hybrid MBS/FEM Simulation Setup, SAE Int. SP-2307, 2011-01-0186, 2011.

Baecker, M., Gallrein, A., Haga, H.: A Tire Model for Very Large Tire Deformations and its Application in Very Severe Events, SAE Int. J. Mater. Manuf. 3(1): 142-151, 2010.

M. Baecker, A. Gallrein, H. Haga: Simulating Very Large Tire Deformations with CDTire, SAE 2009-01-0577, 2009.

M. Bäcker, R. Möller, M. Kienert, B. Bayram, M. Ozkaynak: Lastdatenermittlung für die rechnerische Lebensdauerabschätzung eines neuen Bustyps, MP Materials Testing 05/2009, Seite 309-316.

H. Haga: Development of Tire Model for Large Input Force, JSAE 20095684, 2009.

Yang, X., Medepalli, S.: Comfort and Durability Tire Model Validation, Tire Science and Technology, TSTCA, Vol. 37, No. 4, October – December 2009, pp. 302-322.

A. Gallrein, M. Baecker, H. Horiuchi, H. Naito: CDTireMC: A New Physical Tire Model for Spindle Load Prediction of Motorcycle Tires Including Very Large Inclination Angles on Rough Roads, 27th Annual Conference on Tire Science and Technology, Sept. 15/16 2008, Akron, Ohio, USA, to appear in Tire Science and Technology, 2009.

A. Falkner, W. Reinalter, W. Tieber: A validated simulation method for describing the effect of road-excited vibrations on the development of a vehicle, International Journal of Vehicle Design 2008 - Vol. 47, No.1/2/3/4 pp. 3-18.

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LMS International: LMS Comfort and Durability Tire User Guide, 2007.

S. Heine, C. Hackmair, P. Schneider, A. Wölfl, G. Jung, M. Bäcker: Optimierung von Prüfsystemen mithilfe virtueller Methoden am Beispiel des fahrdynamischen Fahrwerksprüfstandes, MP Materials Testing 09/2007, Page 488-490.

A. Gallrein, M. Baecker: CDTire: a tire model for comfort and durability applications, Vehicle System Dynamics Vol.45, Supplement, 2007, pp.69-77. 

H. Haga: Evaluation of Road Load Simulation on Rough Road Using Full Vehicle Model, 2007 JSAE Annual Autumn Congress Proceedings, No.123-07 p.21-24 (2007).

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H. Haga : Evaluation Method for Road Load Simulation, 2005 JSAE Annual Spring Congress Proceedings, No. 27-05, p.9-12 (2005).

A. Gallrein, J. DeCuyper, W. Dehandschutter, M. Baecker: Parameter Identification for LMS CDTire, 3rd Int. Tyre Colloquium, Tyre Models for Vehicle Dynamics Analysis Proceedings, Vehicle System Dynamics Vol.43, Supplement, 2005, pp.444-456.

H. Haga: Evaluation Method for Road Load Simulation Using a Tire Model and an Applied Example, 3rd Int. Tyre Colloquium, Tyre Models for vehicle Dynamics Analysis Proceedings, Vehicle System Dynamics Vol.43, Supplement, 2005, pp.281-296.

H. Haga: Evaluation of Tire Models for Durability Loads Prediction Using Suspension on Drum Environment, 2005, SAE 06M-266.