Rough Road Vehicle Simulation in MotionSolve – Belgian Blocks

John_Dagg_0
John_Dagg_0
Altair Employee
edited August 2 in Altair Exchange

Overview

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PREFACE

Physical vehicle testing is expensive and resource intensive. Vehicle modeling and simulation provide an efficient alternative which can be implemented earlier in the design cycle to understand a vehicle’s dynamics. Multibody dynamics software such as Altair MotionSolve allows users to set up and analyze a wide range of dynamic systems, including vehicles. Altair’s MotionSolve allows the simulation of a large selection of vehicle events to analyze vehicle performance parameters. Results can be used to refine vehicle design and improve occupant comfort.

INTRODUCTION

In this model, a Sedan drives over a Belgian block road surface. The tires are modeled using Altair’s proprietary enhanced FIALA tire model which uses an elliptical cam contact method to accurately predict forces despite rough terrain. The goal of the model is to analyze the displacement of the suspension over time allowing the estimation of rider comfort.

 

Pre-Requisite

SOFTWARE REQUIREMENTS

  1. MotionView (2023 or newer)
  2. MotionSolve (2023 or newer)

MODEL FILES

  1. Belgian Blocks Zip (See Attachments)

Usage/Installation Instructions

MODEL SETUP

  1. Enable vehicle tools in extensions. File > Extensions > Vehicle Tools

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  2. Enable Entity Browser, Entity Editor, and Model Browser under the View tab.

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  3. Under the Vehicle Tools tab, click assembly to create a vehicle. Use the default settings unless specified otherwise.

    Page 1: Full vehicle with driver
    Page 2: Front wheel driver
    Page 3: Front suspension – Frnt SLA susp (1 pc LCA)
                     Rear suspension – Rear twistbeam susp
    Page 4: Default options
    Page 5: Front shocks – Frnt shock absorber (with cylindrical jts)
                     Rear shocks – Rear shock absorber (with cylindrical jts)
    Pages 6-10: Default options
    Page 11:     Click finish

  4. Update the tire properties.
      • In the Model Browser, select the front tires under AutoTires > Tires.

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    • In the Entity Editor, update the tire property file to the fiala_tire_with_cam_contact.tpf file included in the Belgian Blocks zip. Whenever making a file selection, ensure the correct file type is being searched for.
    • In the Entity Editor, update the road property file to the Belgian_Blocks_Road.crg.
    • Repeat steps i-iii for the rear tires.

  5. Add a road graphic.
    • Select the Road Tools icon to create a road graphic. Select the Belgian_Blocks_Road.crg file and hit ok.

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  6. Update the road graphic orientation.
    • In the Model Browser, open the graphics dropdown and select the road graphic.
    • In the Entity Editor, open the graphic marker selection menu by double clicking the three dots next to graphic_marker.
    • In the popup, deselect only show entities within valid scope. Follow AutoTires > Markers > Road Reference Marker Front and select the left marker. 


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    • In the Model Browser select the Road Reference Marker Front by following AutoTires > Markers.
    • In the Entity Editor, update Sym Orient to be Leading-Left. Change the 2nd Axis Dx value to -1 to rotate the graphic 180 degrees.

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    • In the Model Browser, follow AutoTires > Points to select Front Ground RM Marker.
    • In the Entity Editor subtract 50 mm from the Z value.
    • Repeat vi-vii for Rear Ground RM Marker.

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  7.  Add a road event.
    • In the Entity Browser follow VehicleTools > Events > Car & Truck and select RoadCourse.
    • Select the RoadCourse in the Model Browser.
    • In the Entity Editor, update the path profile to road centerline.
    • In the Entity Editor, under road settings, change road selection to road file and update the road file to Belgian_Blocks_Road.crg.

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SIMULATION STEPS

  1. The model is now ready to run. Open the run dialog, select an output directory, select run offline, and hit run. MotionSolve will run a static and transient analysis.

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  2. After the simulation is completed, select results in the new window to view the animation. Alternatively, open run history next to the run icon, navigate to the model’s name, and select animate.
  3. A report detailing many vehicle performance metrics can be generated by clicking report in MotionView and selecting the run.

Post-Requisite

RESULTS

After running the simulation, the motion of the vehicle can be viewed in MotionView or opened in HyperView for more analysis options. Outputs created in MotionView can be viewed as plots in HyperGraph. For example, shock displacements can be plotted over time. The data obtained from the analysis can be used to inform design revisions. For example, it could be useful to test different damper settings, spring rates, geometry or weight distribution to improve vehicle performance and comfort.

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Sedan motion on the Belgian block road.

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Sedan motion side view.

 

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Displacement of the vehicle from the center of the road. 

 

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Front shock displacements over time.

CONCLUSION

In this article, we learned how to set up a basic vehicle model. Implementation of tire and road files allowed the simulation of rough terrain, in this case a Belgian block course. After performing the analysis, the animation can be viewed, and a wide array of vehicle data can be plotted. The results can be used to inform design changes to improve vehicle performance and rider comfort.  

AUTHORS

John Dagg, Systems Engineering Intern

Chris Fadanelli, Solution Engineer - Systems Integration

Ananth Kamath Kota, Global Technical Manager - Systems Integration

 

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