B
Ben C
Guest
On 2007-03-14, jim beam <[email protected]> wrote:
> Ben C wrote:
>> On 2007-03-14, jim beam <[email protected]> wrote:
[...]
>>> to say that mechanical stress is reduced because the origin has
>>> shifted is also incorrect in the context of wheelbuilding because
>>> stress will have to be re-increased back to the desired pre-tension
>>> level.
>>
>> On the whole spoke, yes, but not on the individual "fibres" that have
>> deformed during stress relief? They've strained a bit and are therefore
>> under less tensile stress.
>>
>> Anyway I thought you were supposed to stress-relieve after final
>> tensioning. So there's an overload from desired pre-tension and relax
>> back to desired pre-tension. What's the re-increase?
>
> all the yielding /during/ build and "stress relief" will deform hub
> holes and therefore move origin. after all is seated, there is no more
> deformation so no more "stress relief". "stress relief" /after/ final
> tensioning will achieve nothing if previous work was done right.
Yes indeed, but this is a different scenario. This could happen, the
stress-relief scenario could also happen, or a bit of both depending on
the components used. Whether those elbows remain close to yield after
the build is not currently known. We need an X-ray diffractor and lots
of test wheels to settle that one.
> Ben C wrote:
>> On 2007-03-14, jim beam <[email protected]> wrote:
[...]
>>> to say that mechanical stress is reduced because the origin has
>>> shifted is also incorrect in the context of wheelbuilding because
>>> stress will have to be re-increased back to the desired pre-tension
>>> level.
>>
>> On the whole spoke, yes, but not on the individual "fibres" that have
>> deformed during stress relief? They've strained a bit and are therefore
>> under less tensile stress.
>>
>> Anyway I thought you were supposed to stress-relieve after final
>> tensioning. So there's an overload from desired pre-tension and relax
>> back to desired pre-tension. What's the re-increase?
>
> all the yielding /during/ build and "stress relief" will deform hub
> holes and therefore move origin. after all is seated, there is no more
> deformation so no more "stress relief". "stress relief" /after/ final
> tensioning will achieve nothing if previous work was done right.
Yes indeed, but this is a different scenario. This could happen, the
stress-relief scenario could also happen, or a bit of both depending on
the components used. Whether those elbows remain close to yield after
the build is not currently known. We need an X-ray diffractor and lots
of test wheels to settle that one.