Learning Forum

[Ziyada Sultan]

Hello everyone.
I'm totally new here and I was wondering if anyone could help me it's very urgent thank you!!!!
I want to calculate the rolling resistance on a wheelchair wheel and a cobblestone road interaction on ansys 2021 software and I'm doing it under different weights as different users have different masses and under different tire pressure/inflation. The tire material is rubber and I'm working on a component level(considering only the wheel of the wheelchair).... steady-state propulsion. I need to know what analysis to use.....I have the tire geometry so far but I need the cobblestone road and its property which I couldn't find(coefficient of friction).....does ansys calculate rolling resistance?

[Dave Looman]

This isn't a typical application with a well-established approach.  If the wheel is relatively rigid, the horizontal force required to push the wheel over a cobblestone could be calculated by hand, based on the angle between a line from the center of the wheel to the touching point of the wheel and the cobblestone and the weight per wheel.  A more realistic analysis would connect the four wheels with a rigid frame and assume only 1 or 2 wheels were being lifted over a cobble stone at a time.  Rubber tires would help moderate the force required.  A static structural analysis should be adequate.   Point masses can be used to model the weight.

[Ziyada Sultan]

Thank you Dave for your reply!

What I want to do is an explicit dynamics analysis because I want to know the effect of rolling resistance on manual wheelchair propulsion as a user propels their wheel on everyday use..... their are different kinds of road surfaces that could be encountered by a wheelchair user and I'm trying to show the effect of a cobblestone road( having a macro textured rough irregularities).....the simulation I want to do is on the rear wheel with 24 inch diameter and with 50 and 75 psi tire inflation and 50 and 60 kg user weight.... going at a speed of 0.48 m/s. 

I hope this clarifies things.....

Thanks again for your help....

 

[Dave Looman]

It sounds like you need a special purpose code for that.  Ansys Mechanical is more of a general purpose code.  I don't support LS-DYNA, but it has been close to the automotive industry over the years and may have special purpose capabilities to model road roughness.