# Friction coefficient of Mud and grass

1. Jun 3, 2014

### KentJacobsen10

Hi Guys,

Just wondering if anyone knows of the friction coefficient of Mud?

i am designing a device that gets pulled through fields of thick grass and mud. And i am wanting to know what the friction coefficient of Mud would be so i can calculate the maximum frictional force on the device, which it turn will help me calculate all the torsional and bending moments on the frame work.

the bottom of my device will mostly be steel.

Cheers

2. Jun 3, 2014

3. Jun 3, 2014

### Barron

Friction coefficient probably isn't a very useful way of estimating the friction force here. The friction force depends on much more than just the contact normal force. Are you plowing the mud so you have to determine the viscous fluid losses? Or are you skimming over the surface so it's more like a lubricated solid? The force for flattening the grass will also depend on the size of the skid more than the normal force.

Probably easiest to get a forcemeter and pull something through the mud to test it.

4. Jun 3, 2014

### KentJacobsen10

I am skimming over it.
Basically its a mower unit with side skids, so points of contact is the mowers rear roller and the skids on either side. i just need to find the opposing force of the mud/thick grass to make a rough estimate of the material thickness needed.

5. Jun 3, 2014

### 256bits

If you pull your mower over gravel, or a skid hits a protruding rock, would that factor into your material thickness needed, for wear and dents to the skid/structure?

6. Jun 3, 2014

### KentJacobsen10

it would not effect the objective of my calculations. i have beams attached to the mower, that are attached to the tractor. if my mower undergoes a high opposing force the beams will undergo bending and torsion. thus i needed to calculate the possible opposing forces. the mower and skids are made well so rocks won't damage them.

However i found the friction coefficient i was looking for , it is approx. 0.57.

Thanks for all your help though.