Searching for a Metal with High Modulus 2

[ShKAS]

I am in need of a metal that can be compressed repeatedly (preferably thousands of times) to approximately 95% of its overall height, and rebound to near its original height. It must do this in a constant 400F degree environment.

Any suggetions are greatly appreciated.

 

[GregLocock]

You need a titanium alloy valve spring. Thousands of times is easy.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[ShKAS]

Greg, thanks for the reply. Would titanium wire itself have this capability? I'm actually looking for is a solid material like wire or bar stock.

Alan

 

[Corn]

Your title topic and your stated need are confusing to me. I don't believe a metal of any type will not be found that will simply compress 5% and rebound, much less one with a high modulus. This naturally leads one to the selection of a spring design. Greg suggests a Ti valve spring. This might work great yet, a helical coil like usually employed in a valve spring is just one spring type of many. Titanium actually has a relatively low modulus. Many metals will make perfectly good springs in any number of configurations to compress 95% and rebound millions of times at 400F. Some questions to address before begining a spring selection are: What is the desired magnitude of the force at the begining and end of stroke? What is the desired variation of force between the end points? (Your request suggests that a linear variation of force from zero would be acceptable, but other profiles might be better.) What is the stroke? What contraints are there on the envelope? What materials will the spring bear against? What are the environmental conditions other than temperature? (i.e. what radiation, gases, and vapors are present, would the device ever be cycled below the dew point or be otherwise wetted?) How important are weight and cost? What are the consequences of a failure of the spring? If the design requires a beginning force, how will the preload be achieved during assembly? How many units are to be produced?

 

[Corn]

Forgive the double negative in my earlier post. To clarify, no solid material exists to do what you want.

 

[ShKAS]

Thanks for the reply. Sorry about the high modulus misnomer. A spring simply won't work in this application. Ideally I'm looking for a metal wire with a diameter of say, .100", that could compress to .095" and rebound close to .100" in the 400 degree environment. The wire would bear agains P-20 steel, and there are no radiation, gasses, vapors, etc., present. If a metal doesn't exist that has the memory required, that answers my question.

 

[amorrison]

What is the force loading?

 

[ShKAS]

I also need to mention that the material only needs to rebound after the load has been completely removed. Thanks.

 

[ShKAS]

The force loading is about 20,000 psi.

 

[WhiteTiger]

Sounds like you may need a stack of ss belleville disc springs. Build the stack properly and you can get almost any deflection and poundage.

 

[GregLocock]

at 400 F?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[WhiteTiger]

302 ss bellevilles are rated at +600F continuous operating temperatures. The temp range is not a limiting factor

 

[TVP]

ShKAS,

20,000 psi is not a force, it is a stress or pressure.

 

[NickE]

And if needed he could go with things like this:

http://www.cloverspring.com

(And they stock 17-7 wich is useable till 600F or so. (and unless you need a bunch, will be not too expensive)

 

[CoryPad]

ShKAS,

You are looking for something that can withstand an elastic strain of 0.95 for thousands of cycles at 400 [°]F. That kind of strain is practically impossible in a metal. Elastomers are the materials of choice for high elastic strain, and there may be some fluoroelastomers that can withstand 400 [°]C. Try Dyneon or DuPont:

http://www.dyneon.com

http://www.dupontelastomers.com/Header/index.asp

Regards,

Cory

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