What this calculator does
It calculates a thermal-cycle life ratio from the test-to-use temperature-range ratio raised to a positive exponent, then converts target use cycles to equivalent accelerated cycles.
When to use it
Use it for a cycle-driven fatigue mechanism when a temperature-range power relationship is supported and frequency and maximum-temperature effects are intentionally held constant or treated separately.
Inputs and formula
Temperature range is a difference, so kelvin or degrees Celsius may be used consistently. The test range must exceed the use range.
AF = (ΔTtest / ΔTuse)mEquivalent test cycles = target use cycles / AFWorked example and interpretation
For a 40-degree use range, 120-degree test range, exponent 2, and 10,000 target use cycles, AF is 9 and equivalent accelerated exposure is about 1,111.111 cycles.
Practical notes and limitations
This is the reduced temperature-range portion of a modified Coffin-Manson model. It omits cycle frequency and maximum-temperature terms, dwell and ramp effects, creep, and interaction with vibration. Do not use it if the accelerated profile creates a different crack or interface mechanism.