Tire model in AMESim


Hi everybody,

I'm trying to simulate a suspension system of a multi body vehicle coupled with a the tire kinematic model VDTIRKIN00 in AMESim as used in the Off-Highway chassis system demo simulation of a tractor.
The vehicle has a mass of 8 to, the vertical stiffness of the tire is set to 300 kN/m and the vertical damping is set to 30 kNs/m.
At five seconds the first tire hits a bumper of a height of 0.3m and the result of the tire deformation (gap/clearance of vertical spring/damper) is seen in the picture below.
Can anybody tell me the reason for that huge deformation of >0.3m?



Re: Tire model in AMESim

Siemens Experimenter Siemens Experimenter
Siemens Experimenter


the VDTIRKIN00 submodel is only valid for smooth obstacles, you should only use it with obstacles that have features larger (in the horizontal plane) than a few times the contact patch length of the tire. VDTIRKIN00 can't handle cleats, sharp bumps...

The tandem egg options available with the new tire models of V1500 and later can tackle those small (short and abrupt) obstacles. Have a look at the  Solutions->automotive->chassis->Cleat in turn-> tandem egg. The submodel is not meant for extreme situations though (when dynamics are faster than wheel hop mode or when the ground-tire contact is high relative to the sidewall height).

If the obstacle is short and high (relative to sidewall height) such as a curb, tree log or if the vehicle is going fast (so that the excitation is higher frequancy than wheel hop),... you should look into external tire models such as Swift (from TASS now part of Siemens) or FTire (from cosin). See the Swift and FTire demos next to the tandem egg demo.

If you are looking at abrupt obstacles that are 0.3m high, even with large tires, you are in the realm of these external advanced tire models.

If you don't care about the 'abrupt' part but want to look at how the suspension responds when a wheel is 0.3m higher than the three others then you can keep VDTIRKIN00 but you need to smooth out the transition over a meter or more.