"anyway, stress man says ignore the variance in E (there is a small effect)and look to geometric/mass changes, i.e. hub length, axle length, radius, wall thickness."
Cheers Paul. Stress man has basically said the same as Ian in this case. Harder axles and softer axles will behave the same, as E doesn't vary enough to make a significant difference. I'm dubious about the local yield thing too, but if it doen't have an effect, the hard, soft and medium axles should all feel the same to drive with.
Could you ask him if we'd expect any local yield close to the bearing without permanently bending the axle? The stress isn't high enough unless you clout a kerb, and it's the "up and down" forces that give the peak rather than the cornering force, which actually reduces the bending moment on the axle. Or alternatively, just ask him if he thinks hard vs. soft axles make a difference, and why? ;-)
As for the dynamic performance, if E is the same, the natural frequency is the same. There's no natural damping effect as the axle is behaving elastically. I just can't see a logical reason hardness makes a difference.
Liam
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