Calculation of risk of flank fracture acc. to FVA 556/III

This calculation method considers the exposure in the center section of the virtual cylindrical gears according to FVA 411

for evaluation of the safety against flank fracture load capacity according to FVA 556/III. The interpolation points for calculation of the stress curves in the material depth depend on the Hertzian contact flattening at the respective calculation point on the line of action of the virtual cylindrical gear. The stress curve is determined using 110 support points in the material depth at eleven evenly distributed calculation points on the line of action of the virtual cylindrical gear.

The scope of the calculation method is limited as follows:

• Hertzian pressure: 500 N/mm² ≤ p_H,lokal ≤ 3000 N/mm²
• Local equivalent radius of curvature: 5 mm ≤ ρ_red,lok ≤ 150 mm
• Case hardening depth: 0.3 mm ≤ CHD₅₅₀ ≤ 4.5 mm

If these quantities are outside the valid range, the calculation procedure is aborted. Statements on the risk of flank fracture can be made from a material depth of at least half the Hertzian flattening width. The Hertzian flattening width is output.

Source:

• Bojadiev, I., Tobie, T.; Stahl, K.: Nachrechnung Flankenbruch Kegelräder (Recalculation of bevel gear flank fracture). FVA Research Project 556/III, FVA Issue 1100, Forschungsvereingigung Antriebstechnik e. V., Frankfurt, 2014.
• Pellkofer, J.; Drechsel, A.; Hein, M.; Stahl, K.: Erweiterung KNplus (Extension of KNplus), FVA Research Project 49/XIII, FVA Issue 1342, Forschungsvereingigung Antriebstechnik e. V., Frankfurt, 2019.