Rethinking Motorcycle Suspension: Girder Suspension Stability and Dynamic Simulations

Vishvam

Rethinking Motorcycle Suspension: Challenges in Achieving Precision and Stability with Girder Suspension Configurations in Dynamic Simulations 

PREFACE 

The dynamics of motorcycle suspension systems, particularly unconventional designs like girder suspension, present unique challenges in optimizing ride stability and handling. Physical testing of these systems across different riding conditions can be costly and time-consuming. Multibody dynamics simulation provides an efficient solution to model and analyze the complex interactions between components. Using software such as Altair’s MotionSolve and MotionView engineers can simulate the behavior of girder suspension systems under various load conditions, enabling detailed evaluation and refinement of the design. Through these simulations, it becomes possible to enhance ride performance and ensure the suspension system operates effectively across diverse scenarios.

INTRODUCTION 

In the world of motorcycle engineering, suspension systems are at the heart of performance and rider control. While telescopic forks have long dominated the scene, the revival of girder suspension offers a fascinating alternative, combining historical innovation with modern engineering challenges. Unlike traditional systems, the girder suspension’s unique structure offers the potential for superior rigidity and improved handling—but unlocking these benefits requires a deep understanding of the complex dynamics at play.

The girder suspension’s unconventional geometry introduces intricate challenges in balancing load distribution, ensuring stability, and managing suspension kinematics. As with any critical component of a motorcycle, the stakes are high: the rider’s safety, comfort, and performance depend on the precise interaction of forces and movements throughout the system.

This article dives into the multibody dynamics simulation of a motorcycle fitted with a girder suspension, using Altair MotionView/MotionSolve to model and analyze the system’s behavior. Through simulation, we explore how the suspension responds to various forces and conditions, identifying potential issues and fine-tuning the design for optimal performance. Whether it’s navigating sharp turns or handling uneven terrain, this study aims to refine the girder suspension, pushing the boundaries of what’s possible in modern motorcycle dynamics.

SOFTWARE REQUIREMENTS

Altair MotionView (2024.1 or newer)

Altair MotionSolve (2024.1 or newer)

MODEL FILES

Girder_Suspension_Motorcycle.zip (See Attachments)

Understanding the Model Definition in MotionView

This model setup assumes a level of familiarity with Motionview/Motionsolve. A motion-ready model called Girder_Suspension_Motorcycle.mdl is available for reference in the attached zip file.

The simulation model focuses on the front suspension system of the motorcycle, featuring a girder suspension design. The girder suspension is connected to the frame through joints, simulating real-world mechanical linkages. While certain dynamic aspects, such as internal damping mechanisms or manufacturing tolerances, are not explicitly modeled, the simulation emphasizes the system’s response under operational conditions. The multibody simulation investigates how the forces during different types of events influence the stability, ride comfort, and handling characteristics, providing insights to refine the girder suspension's design for optimal performance.

MODEL SETUP

Bodies:

• The model contains a Frame, Front Girder suspension unit, Rear mono suspension unit, swingarm, spindle and wheels with Autotires from Motionview.
• The dummy rider is simply fixed to the frame to visualize and simulate the rider effects on the motorcycle.

Joints:

• The following images show a clear architecture of parts included in front girder suspension.

• The following joints combination is used to avoid any redundancy in the model

SIMULATION STEPS

1. The model is now ready to run. Open the run dialog, select an output directory, select run offline, and hit run.
2. After the simulation is completed, select results in the new window to view the animation.
3. A report detailing many vehicle performance metrics can be generated by clicking report in MotionView and selecting the run.

RESULTS

After the completion of the analysis, the vehicle’s motion can be viewed in HyperView. Outputs including steering angles, driver inputs, vehicle accelerations, shock displacements, and more can be plotted using HyperGraph. Many of the key performance indicators are automatically graphed by creating a report in MotionView.

CONCLUSION

The multibody dynamics simulation of the girder suspension successfully highlights its potential for enhanced rigidity and handling in motorcycles. By leveraging Altair MotionView and MotionSolve, engineers can analyze and optimize suspension performance under diverse conditions, addressing stability and load distribution challenges. These simulations provide valuable insights to refine the girder suspension design, ensuring improved ride comfort and control. Ultimately, this approach demonstrates the power of simulation in advancing innovative motorcycle engineering solutions.

AUTHORS

Vishvam N, Solution Engineer - Systems Integration

Girder_Suspension_Motorcycle_archive.zip

Shiva Kumar

Cannot open the mdl file, it says invalid operation and invalid features are found and closes suddenly

i have 2023 version hyperworks, please help me

Vishvam

Hello @Shiva Kumar
Sorry for the issue you're facing. The model has been built on 2024.1 and thus it's not backward compatible with 2023. Please use 2024.1 version of Motionsolve, it should work just fine. The same has been rectified in the article. Thanks!

Shiva Kumar

Thank you for the reply sir,

i have V23, im am interested in performing these type of studies but can't find tutorials anywhere.

in the altair learning the tutorials are basic, can you please guide me where i can find such tutorials.

Thank you

Vishvam

@Shiva Kumar
You can always install the latest version from the marketplace. (Click here)

As you mentioned the eLearning tutorials are basic, just to help you get around the software. If you are interested in vehicle dynamics, we have an eLearning tailor-made for using Vehicle modelling. You can explore the following eLearning which will be helpful.
MotionSolve v2023 for Vehicle Modeling

You can also go through the following FAQ page and model repositories for more resources.
Altair MotionView/MotionSolve Frequently Asked Questions
Altair MotionView/MotionSolve FAQ and Model Repository

Hope this helps!

Shiva Kumar

Hii sir,

I have gone through the Vehicle modelling tutorials as well but it has everything pre built. It doesn't explain about the tires and creating the custom road profiles like in this blog. Thank you for the quick reply. Please share i there are any other tutorials if you know.

Thankyou

Vishvam

Sure @Shiva Kumar
You can go through the documentation for Vehicle modeling. This has in-depth knowledge of all the entities that you will be working with in the vehicle domain.
https://help.altair.com/hwdesktop/hwx/topics/chapter_heads/vehicle_dynamics_modeling_r.htm

For any queries, feel free to mail it to hwsupport@altair.com