Rubber material

Try with google to find damper unde the name "silent block" or rubber damper.

It is better to use an of the shelf available product for your project. The component manufacturer will give you data about the used material.

Design of rubber compnents is quite complicated since too many factors do interfere.

Hi, damian and sarah,

Sorry, this isn't my field, but if you want to pursue discussions on CR4, I strongly recommend you to register. You'll be able to get notified of any feedback (by an e-mail alert) if it comes tomorrow, next week or next year! You'll also be able to exchange private messages (PMs) with other CR4 members (sometimes folk don't like posting stuff for everyone to see).

Good luck with your endeavour,

John.

You guys probably would be looking at trying different durometers (hardness rating) of urethane.

Urethane at certain durometers (50-80A) is still rigid enough to support an average person's weight but still have enough "give" to act as a dampener.

You will probably have to experiment with a couple of different durometers, but most plastic wholesalers will give out small samples for you to evaluate.

Good Luck

UFG

I assume your "pushchair" is a non-motorized wheelchair.

1. Polyurethane (PU) rubber is far more durable than other rubber types. You may want polyether PU rubber, which is slightly weaker than polyester PU but endures far longer in high humidity or wet environments, above 70F.

2. It is plausible you do not need PU for shear strength. It may be that high tensile strength combined with moderate elongation (the property called toughness) will suffice. A springlike suspension may suffice.

3. A top material like very thick cotton or ultrahigh molecular weight polyethylene UHMWPE (for wear and puncture resistance) might be the engineering property of better interest.

4. If you want very high shear, Adiprene is one PU brand. I can give other brands in 2 hours' time, beginning 4/8/08. High shear can be attained by having inexpensive solid rubber on top and a weaker thin layer of foam beneath.

5. Do you need puncture resistance or low porosity (for incontinence)? PU foam and solid PU are options.

6. A consideration is a thin lower layer of expensive polynorborene (PN), depending on the needed "feel". PN allows running on concrete and having close to the sensation of running on beach sand.

7. The cheapest approach with satisfactory results may require the feel and fire resistance of Neoprene (a type of rubber different from PU) hospital mattresses.

Summary: You need to define needed engineering properties BEFORE material selection can be done quickly. Also decide whether shear strength is the critical property. To define properties, consider visiting several medical supply places to find items with the needed "feel" (wheelchairs or beds). Then contact items' manufacturers to learn the items' properties and/or material content. I can help with specifics beginning 4/8/08.