PSI - Issue 46

Robert Basan et al. / Procedia Structural Integrity 46 (2023) 62–67 Robert Basan et al. / Structural Integrity Procedia 00 (2019) 000–000

63

2

Nomenclature b

fatigue strength exponent (-) fatigue ductility exponent (-) Young’s modulus (Nmm -2 ) shear modulus (Nmm -2 ) Brinell hardness (HB) Vickers hardness (HV)

c

E G

HB HV

material parameter in the Fatemi-Socie crack initiation criterion (-)

k

yield stress (Nmm

-2 )

R e

 f '  n  f '

fatigue ductility coefficient (-)

maximum normal stress acting on critical plane (Nmm -2 )

max

fatigue strength coefficient (Nmm -2 ) maximum shear strain amplitude (-) number of load reversals (-)

 (  max /2)/2

2 N f

1. Introduction Determination of load-carrying capacity or durability of engineering elements, components and structures is, with the exception of the simplest ones, quite complex task. Intricate geometries, complex loading, variable operating conditions as well as numerous influences need to be taken into account. This is particularly true for highly loaded components exposed to rolling-sliding contact loading such as gears, rollers or bearings because combination of geometry, loading and operating conditions result in a complex multiaxial states of stresses and strains in the material (Aberšek (2004), Dowling (1993)). Simplified representation of the problem which already reveals part of the complexity is shown in Figure 1 where using very simplified terms such as shear loading/stress and shear strength, different scenarios are presented and corresponding type of fatigue damage that occurs at the gear teeth flanks are shown (Hyde (1996)).

Surface damage (pitting)

Deep subsurface damage (case crushing)

Subsurface damage (flake pitting, spalling)

No damage

Stress

Distance from surface

Shear fatigue strength

Shear stress

Fig. 1. Simplified representation of shear fatigue strength and shear stresses at gear teeth flanks and related typical fatigue damage types/forms