Fatigue Testing
In almost all chain applications, each link undergoes load and no-load phases, thus being subjected to varying stress and strain conditions (dynamic or periodically changing loads).
Since the limits of materials for dynamic and static loads differ significantly due to fatigue behavior, fatigue strength — and not just the ultimate tensile strength — is the limiting design criterion in chain technology.
A roller chain can be operated in the load range below the fatigue strength without failing during service due to component breakage.
Above the fatigue strength, the chain is operated in the so-called finite life range, meaning it can withstand a certain number of load cycles but will inevitably fail.
The higher the load, the fewer the number of load cycles (drive revolutions) it can endure.
