Material and Heat Treat condition of a Flexible Blade

[DDrinan]

I have designed a anti-roll sytem that in a new application of excessive travel, is now bending the blades that are part of spring rate used in the system. We originally used 4130 to 42C, then went to 4340 all the way up to 53 C and are still bending the blades. We tried making some out of 1095 and brought them to 43C and they snapped.
I need a suggestion of materials and heat treat to prevent to blades from yielding, without catstrophic failure.

 

[eromlignod]

1095 was probably a pretty good choice. Did you temper after hardening?

Don
Kansas City

 

[hydtools]

You may have to re-examine the design. There may not be a material change solution for the current design.

Ted

 

[arunmrao]

A lower carbon,but higher silicon with a proper heat treat should provide resilience. EN42 series is popular as spring steel material.

I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
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[drawoh]

DDrinan,

How are you doing your structural analysis?

In your calculations, you know deflection. You need to calculate the forces, the moments and the stress. You have to use the equations backwards. The bending equations from the handbooks are based on double integration method, and are reliable for deflections of up to 10% of your spring length. You may have to seriously read up on this, or use a good FEA[ ]program.

Have you considered beryllium copper or titanium for your springs? These materials are equivalent to spring steel for strength, but they have lower elastic moduli. You can bend them more before they exceed their yield stresses.

When I design springs like this, they are statically loaded and I do not need to worry about fatigue. Your life is not so simple. It may be possible to design a steel spring for infinite life. Beryllium copper and titanium have lifespans.

JHG

 

[GregLocock]

Make the blades thinner but wider

Cheers

Greg Locock

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