Haigh

Haigh Calculator performs the calculation of the Haigh fatigue fatigue check diagram, permitting to key in geometrical, dimensional and finishing properties of the workpiece

This tool solves Haigh diagram using different criteria that permit to convert the medium and alternated stress to an equivalent alternated stress. From this point of view there is no distinction between traction/compression stress, bending, torsion or an equivalent stress obtained from a multiaxial stress state. If you want to calculate a stress different from traction/compression data related to "compressive" limit load have no sense. If you are in a torsion stress state, limit loads will be τ (tau) and not σ (sigma).

Usage:

1. Insert data related to material, geometry, dimension and finishing
2. Insert data related to application properties
3. Select criterion
4. Visualization of Haigh and Wholer diagrams updated at the bottom of the page

MATERIAL PROPERTIES
σr / τr [MPa]	Tensile Strength, ultimate
σs / τs [MPa]	Tensile Strength, yield
σrc [MPa]	Compressive Strength, ultimate
σsc [MPa]	Compressive Strength, yield
σfa / τfa[MPa]	Fatigue load limit (alternate)
N	Cycles No
	Unlimited fatigue
PART PROPERTIES
Kt	Shape factor
q	Notch sensitivity
Kf	Notch factor
b2	Surface quality factor (finishing)
b3	Size factor
ACTUAL LOAD LIMIT
σ′f / τ′f [MPa]	Actual load limit
APPLICATION PROPERTIES
Δσ / Δτ [MPa]	Stress amplitude ( 1/2 * (MAX - MIN) )
σmed / τmed [MPa]	Mean stress
σmax / τmax [MPa]	Maximum stress
σmin / τmin [MPa]	Minimum stress
	Criterion	Sodeberg Goodman ASME Gerber
EQUIVALENT ALTERNATED FATIGUE VALUE
Δσeq [MPa]	Equivalent alternated fatigue value
N [cycles]	Life cycles
η	Coefficiente di sicurezza