Looking for a Material That Will Displace Like Sand When Under Load

[ntonkin64]

Hello,

I'm looking for a durable material that can displace like sand when someone walks on it. I am considering closed-cell polyurethane foam. I would prefer to have a material that has small individual grains similar to sand but much lighter. If this isn't possible then a solid gel/foam material that has a large displacement when a force is applied might work well. Please let me know if you have any ideas.

Thanks.

 

[Demon3]

If you mean the way that wet sand first flows then becomes solid when you step on it that's called dilitant behaviour so your search term needs to be dilitant fluid. There are lighter materials that do the same, for example corn starch in water. Fun to play with. The effect occurs when you have almost the maximum packing fraction of particles with just enough liquid between them to let the dispersion flow. When pressure is applied it squeezes out enough liquid to get to the maximum packing fraction where the viscosity approached infinity and the particles all touch with no liquid lubricating their contact surfaces.

Chris DeArmitt

Expert consulting & training

http://www.phantomplastics.com

 

[ntonkin64]

Thanks for the fast response Chris. I will also experiment with corn starch and water. How long can the corn starch and water react in this manner once mixed? 4 days, 4 months, 4 years? I was wondering if there is a degradation in the dilitant behavior?

I also found a product at a dollar store that behaves kind of like what I'm looking for. It is essentially a stress ball filled with microbeads. I'm sure there are many different types for microbeads that can be used. Do you know the type of microbeads that are typically used in a stress ball application? Where might I be able to buy microbeads?

http://www.marblesthebrainstore.com...469_a_7c1757&gclid=CPLey5Gr5LgCFdGj4Aodql0Amg

 

[ornerynorsk]

Your mention of the stressball reminded me of a product or group of products that was manufactured years ago under the tradename of "Floam". I've no idea if it is still manufactured, but similar knock-offs came into the marketplace shortly after its introduction. Before its application in novelty toys, it was used as filler in various medical cushioning and support products. I don't think its behavior is that similar to sand, though.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[btrueblood]

Had a thought similar to ornerynorsk. I think the stress balls have simple styrene beads (styrofoam before it gets steam-treated to expand it), perhaps with a silicone oil?

 

[geneiusxie]

I'm pretty sure you can use some non-volatile liquid instead of water so it lasts much longer. Silicone Oil or Mineral Oil is cheap and works.
You can still use sand. It's cheap and works great.

 

[Demon3]

Yes, it works with other fluids too. An example is stab-proof vests that are liquid and comfortable then when stabbed they become hard and resist the knife. You can find information online but that's probably not water-based. One would want a non-volatile fluid for longevity.

Chris DeArmitt - PhD FRSC

Materials Consulting & Training

http://www.phantomplastics.com