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Re:Torsion bar

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fastfred

Aerospace
Nov 1, 2004
20
US
Hello guys,we are tasked to reengineer a rate gyro that has a floating gimbal assembly,the rate is determined by the force exerted on the Torsion Bar.How can we find out what type metal this is and who can reproduce such a part for us, we can really use the help now.
 
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fastfred,

If the final application is some type of aerospace device, then I don't see how you can avoid destroying the sample if you do not already have engineering drawings or some other technical documents. Merely knowing the general chemical composition will not be sufficient. Other important items include specifics of the chemical composition like impurity elements (O, N, S, P, Sn, etc.), strength, hardness, microstructure (grain size, grain size variation, texture, etc.).
 
Hey guys, I think this torsion bar needs to be sent out to a metal expert.Please advise on a company (or person) that we can contact.
Thanks,Fastfred
 
It might be better and less expensive to design it using common spring materials. We have had good success with 4340.
 
We would love to find an alternative, but this is a re-engineering project that has to be the same materials.
 
What part of the country are you in? It is nice to use loacal labs when you can.
You are going to want composition, microstructure and mechanical properties in addition to all of the dimensional data.

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Corrosion never sleeps, but it can be managed.
 
We are located in Orlando florida,sorry for the delay, had to go out of town.
 
In a small rate gyro that I have seen in the past the torsion bar was designed for a maximum deflection angle of 2 degrees and the angle was measured by a mini pickoff (or resolver?). Knowing the deflection angle and the torsion bar dimensions you can calculate the torsion stress. From the stress you can decide which stainless ateel alloy to use. I assume that if the torsion bar is para-magnetic it is probably be 17-4PH or 15-5PH or AISI 416. Otherwise it may be A-286 or AISI 303. It depends on the stress level at maximum angle deflection.
 
Another way to determine material would be to use FEA. If you have the shape, know the load at 2 different deflection distances you should be able to narrow down the material. This will probably cost more than a metallurgical test, but the sample would not be destroyed.
 
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