DIN 743 B1-2000(English version)Shafts and axles, calculation of load capacity
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DIN 743 (supplementary sheet)
Content
Page Foreword . . . . . . . . . . . . . . . . 2
1 Scope . . . . . . . . . . . . . . . 2
2 Normative references . . . . . . . . . . . . . 2
3 Symbols, Definitions and Units . . . . . . . . . . 2
4 Application example . . . . . . . . . . . . . 2
4.1 Proof against fatigue fracture and permanent deformation of stepped shafts
under bending and torsion . . . . . . . . . . . . 2
4.2 Proof against fatigue fracture and permanent deformation of shafts with
feather key slot under bending and torsion . . . . . . . 4
4.3 Proof against fatigue fracture and permanent deformation of axles with
feather key slot under bending . . . . . . . . . . . 6
Foreword:
The German standard DIN 743 has been prepared by the German institute for standardisation and the Institut für Maschinenelemente und Maschinenkonstruktion of the technical university of Dresden, Germany.
The standard consists of 4 of parts:
- Part 1: “Introduction, Basics”
- Part 2: “Stress con centration factors and fatigue notch factors”
- Part 3: “Material strength value”
- Supplementary sheet 1: “Application examples”
1 Scope
This standard comprises application examples for proof against fatigue strength according to DIN 743-1, 743-2 and 743-3.
2 Normative references
DIN 743-1
DIN 743-2
DIN 743-3
3Symbols, Definitions and Units
4Application example
4.1Proof against fatigue fracture and permanent deformation of stepped shafts
under bending and torsion
This example merely serves for demonstrating the calculation process.
Known:
Dimensions:
D = 50 mm
d = 42 mm
r = 5 mm
t = 4 mm
Load (section cross at d):
Material:
34CrMo4 (strength values according to DIN 743-3, d B≦ 16 mm):
Surface roughness: R Z = 5 μm
Unknown:
Safety of proof against fatigue fracture under type of load 1 and against exceeding of the yield strength.
Calculation: (calculation scheme see DIN 743-1 Annex B). The calculation is made with notch and stress concentration factors according to DIN 743-2.
a)Overall influence coefficient for bending
-Stress concent ration factor ασ according to image 9 of DIN 743-2 with d/D = 0.84; r/t = 1.25; r/d = 0.119; ασ = 1.557
-Stress gradient G’ according to table 2 in DIN 743-2 with υ= 0.179; G’ =
0.542 mm-1
-Technological size coefficient K1(d eff) (see page 6) according to equation
(14) or image 13 in DIN 743-2 with d B= 16 mm and d eff= 50 mm