Do frames get soft after a while?
08-25-12, 09:04 AM
#26
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It's a little too easy to design a marginal spring to use that as analogy to any other structure. It's not clear in your example what really happened. You fixed it by bending the spring. Had the spring bent under use? That doesn't happen with frames
08-25-12, 09:16 AM
#27
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Springs- My understanding is that the reduction of the "springiness" is from the spring collapsing and not the MofE changing. This shortening of the spring (if we're talking about a ball point pen type spring) happens because of the strength not being up to the task. Stiffness (MofE) is how far the spring moves given a known load. Strength is whether there's permanent deformation at a known load. I suggest that the springs are being deformed. Andy.
08-25-12, 09:29 AM
#28
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So that phenomenon is just a result of poor design rather than an inherent shortcoming, eh?
Hard to say; presumably.
Hard to say; presumably.
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08-26-12, 03:32 AM
#29
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SPRINGS DO NOT GET SOFT. END OF.
When a spring is made, the correct procedure for QA following shaping and heat treatment is to scrag the spring. That means giving it an expected maximum loading several tens of times to help set the spring to a fixed length and reach a higher strength. However, because springs are subject to ultrherzian stresses, and because they are quenched and only very lightly tempered to maintain maximum strength, they also don't exhibit a fatigue behaviour more commonly associated with steels as you see them which are quenched and quite noticeably tempered into two phase material.
As a result, springs exhibit fatigue damage, manifesting as microcracks that affect their total strength and cause them to deaden and and sag. This is NOT, I repeat NOT softening.
When a spring is made, the correct procedure for QA following shaping and heat treatment is to scrag the spring. That means giving it an expected maximum loading several tens of times to help set the spring to a fixed length and reach a higher strength. However, because springs are subject to ultrherzian stresses, and because they are quenched and only very lightly tempered to maintain maximum strength, they also don't exhibit a fatigue behaviour more commonly associated with steels as you see them which are quenched and quite noticeably tempered into two phase material.
As a result, springs exhibit fatigue damage, manifesting as microcracks that affect their total strength and cause them to deaden and and sag. This is NOT, I repeat NOT softening.
08-26-12, 10:57 AM
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So, this deadening... I suppose it could conceivably occur in a steel frame, then? Or not, I dunno
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08-26-12, 12:44 PM
#31
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No. It can't.
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