Crane Designer's Fatigue Design

Calculation Procedure
Ultimate strength of material (max 1100MPa)
Applied stress
Diameter
Stress state factor
Size factor
Surface finish factor (approximate values using linear curve fit to tabulated data).

• As Forged
• Hot Rolled
• Rough turned (peak to valley height 30μm)
• Turned/rough ground (peak to valley height 12μm)
• Fine turned (peak to valley height 6.5μm)
• Fine ground (peak to valley height 2.5μm)
• Lapped/rough polished (peak to valley height 1μm)
• Mirror polished

Stress concentration factor
Notch sensitivity factor
Fatigue notch factor
Fatigue limit factor
Fatigue reference stress factor
Fatigue reference stress (90% probability of survival)
Design Stress
Demand to capacity ratio
Allowable Stress Amplitude
Demand to capacity ratio
Calculate σall for given N using power trend line (fit equation: y=cxb)
Generate SN Diagram
Generate Goodman Diagram

Calculation Reference
Petersons Stress Concentration Factors
Machinery's Handbook 18th ed.
Crane Design
BS2573
ISO 4301