Endurance limitation
This is a time window between the fatigue limit and
the elastic limit. A chain is permanently resistant
(remains solid and unchanged) for as long as the
load on it remains below the fatigue limit. Beyond
the fatigue limit, the chain will only sustain the load
for a limited period of time.
In some cases it may be necessary to choose a chain
for loads in the endurance limit range. This may be
due to commercial reasons or justified by conscious
under-dimensioning due to a lack of space. It is also
possible that the chain falls into this endurance limit
range because it was improperly selected. Within this
range, the chain will only sustain the load and remain
solid for a limited time before failing due to fatigue
fractures after a short while. The closer the load gets
to the elastic limit, the more easily the chain will
break. This could happen after just a few hours.
The elastic limit ranges between the breaking load
and the fatigue strength. When used below the elastic
limit the chain will recover its original shape since
this span falls within the elastic deformation range.
Exceeding the elastic limit will result in an immediate
permanent plastic deformation, the link plates are
deformed and the bore holes will become oval.
Fatigue fracture within endurance limit range
Number of stress cycles endured
Fatigue limit range
Plastic deformation
Failure due to fatigue fracture caused by excess load
Overload rupture at
single exposure
F
0
SN curve
Wöhler diagram
Fluctuating stress
Breaking load limit
Elastic limit
Endurance limit
Fatigue limit
∞
FB
FE
FD
Fatigue strength
Fatigue strength or the maximum permissible load
is the limit at which the chain can barely sustain the
fluctuating stress without failing due to fatigue fracture.
The fatigue strength limit is determined with
a fatigue test (SN curve). There is no correlation between
the breaking load and the fatigue strength.
The fatigue strength of a chain is affected by production
standards and quality standards and – unlike the
breaking load – varies greatly between the models
of the different manufacturers. The actual maximum
fatigue strength values for all different KettenWulf
roller chain series are available upon request! These
are constantly lab-tested.
Elastic limitation
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