Flexural Fatigue (Dynamic Fatigue) - What material is best?

[oceanman]

I am developing a water pumping type of application which will involve the use of an elastomer that acts as a diaphragm. The configuration of the diaphragm is not yet set, but it could be in the form of a cylindrical layflat type of tube. In its intended use, it will be cycled rapidly and repeatedly. I would like some advice as to which material can likely survive the most cycles before failing due to flexural fatigue. I am considering polyurethane, silicone rubber and natural rubber. I did a quick internet and patent search and found that polyurethanes can go about one million cycles or so. I could not find other data. Are there general rules of thumb which can predict flex fatigue life, such as material hardness??

 

[Compositepro]

It sounds like a peristaltic pump. Masterflex has tubing designed for that application.

 

[oceanman]

Compositepro,

Thanks for the Masterflex reference. The layflat tube that I want to use is intended to be a very thin plastic or rubber film, perhaps .010 or less in thickness. I will still check out the Masterflex material.

 

[Compositepro]

If it has to be that thin and flexible, and yet contain pressure, about your only choice is a fiber reinforced elastomer or flexible PVC. A braided reinforcement allows great strength with very high flexibility.

 

[oceanman]

Thanks again. The membrane/diaphragm will only separate two incompressible fluids which are at difference pressures. I do not think that needs to be reinforced at all, it just needs to be able to flex millions of times without failing due to fatigue. The best that I can come up with so far is polyurethane.