Rolling contact plot of force in MotionView
I have simulated a rolling contact between bicycle and road in Motionview. The type of contact defined is volume model between the road body and the tyre body. I have provided basic joints for the motion and some forces on the saddle and handlebar. When I plotted the forces acting on the front wheel joint, i got a graph of this form. The spike in the beginning is due to the cycle dropping freely onto the road but I would like to know why the spikes appear later on too in the force plot. I tried changing the damping coefficient values too, but the result has not much difference.
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Bicycle model detailed
Force plot
Bicycle road model
Answers
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Hi-
You should not be using 3D contact like this to model the tire-road interface. There are a number of tire models accessible through MotionView. MF-Tyre (and as of version 2020, the Altair Fiala Tire) support motocyle and bicycle tire physics.
The spikes that occur later in the simulation are likely due to the mesh of the CAD geometry. You can make the mesh finer and finer, but it will still exist for CAD geometry as you can never completely get a perfectly smooth surface, unless you model using a sphere or cylinder with analytical contacts. But again, if you want to model tires, you should be using the AutoTire entity, and tire data (either MF-Tyre MC, or Altair's Fiala based tire model)
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Okay, thank you.
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Altair Forum User said:
Dear Pramodh,
Can you give me a email to send a little doubt? your cae is amazing, i working in a similiar situation.
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Bicycle road model
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FYI, in version 2020 of Hyperworks, we have a 2-wheeler vehicle library. While is it focused around motorcycles and scooters, it is easily adaptable to bicycles, and includes entities for referencing tire models, rather than using 3D contact which is really not a good approach for modeling tires of any kind. We don't use 3D contact for a couple of reasons (there are probably others, but here are two big ones):
1. 3D contact is very computationally expensive relative to various tire models.
2. using 3D contact and friction does not accurately capture the physics of a tire as it is rolling over obstacles, cornering, etc.
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Altair Employee