Stress Concentration Effect Muhannad Al_Waily_Machines Systems Design Stress Concentration Effect Shaft Design Gear Forces Effect Spur gears Helical gears Bevel gears Worm gears Under Static Load Under Dynamic Load Maximum Stress Result Stress concentration Bending stress Axial stress Normal stress Minimum area Direct shear Torsion shear Shear stress Maximum load

Stress Concentration Kt Kts Muhannad Al_Waily_Machines Systems Design Stress Concentration Photo-elastic Measurement of stress Concentration in flat, stopped, notched bar in bending. Kt stress-concentration factor for normal loading Kts stress-concentration factor for shear loading nom & nom are the nominal stresses calculated for the particular applied loading and net cross-section assuming a stress distribution a cross the section that would obtain for a uniform geometry

The theoretical stress-concentration factor at the edge of the hale Stress Concentration at the Edge of an Elliptical hole in a plate. Muhannad Al_Waily_Machines Systems Design The theoretical stress-concentration factor at the edge of the hale exponential function Geometric stress-concentration factors and functions for stepped flat bar in bending. represents the independent variable the coefficient A and exponent b for any one value of ' ' are determined by nonlinear regression on several data points taken from the experimental data

Muhannad Al_Waily_Machines Systems Design r/d r/d Muhannad Al_Waily_Machines Systems Design r/d r/d

Muhannad Al_Waily_Machines Systems Design r/d r/d Muhannad Al_Waily_Machines Systems Design d/D d/D

Stress Concentration Under Dynamic Loading Muhannad Al_Waily_Machines Systems Design Stress Concentration Under Dynamic Loading Fully reversed Repeated Fluctuating Mean or average stress stress range variable stress ratios

Effect of Loading on Endurance Limit-Load Factor Muhannad Al_Waily_Machines Systems Design Kb= load correction factor for the reversed bending load. Its value is usually taken as unity endurance limit for reversed bending load Effect of Loading on Endurance Limit-Load Factor Ka= load correction factor for the reversed axial load. Its value may be taken as 0.8 endurance limit for reversed axial load Ks= load correction factor for the reversed torsional or shear load. Its value may taken as 0.55 endurance limit for reversed torsional or shear load For steel For cast iron For non-ferrous metal and alloys Factor of Safety for Fatigue Loading

Notches and Stress Concentration (Notch Sensitivity) Muhannad Al_Waily_Machines Systems Design Notches and Stress Concentration (Notch Sensitivity) notch sensitivity ' q ' fatigue (dynamic) stress-concentration factor (a)for steels (b)for Annealed Aluminum (c) for Hardened aluminum Stresses

Muhannad Al_Waily_Machines Systems Design

Combined Steady and Variable Stress Muhannad Al_Waily_Machines Systems Design Combined Steady and Variable Stress Goodman method Soderberg method

Goodman Method for Combination of Stresses Muhannad Al_Waily_Machines Systems Design Goodman Method for Combination of Stresses the fatigue stress concentration factor ' Kf ' ductile materials brittle materials bending bending axial loading axial loading torsional or shear loading torsional or shear loading

Soderberg Method for Combination of Stresses Muhannad Al_Waily_Machines Systems Design Soderberg Method for Combination of Stresses the fatigue stress concentration factor ' Kf ' ductile materials bending axial loading torsional or shear loading

Combined Variable Normal Stress and Variable Shear Stress Muhannad Al_Waily_Machines Systems Design Combined Variable Normal Stress and Variable Shear Stress equivalent normal stress due to reversed bending torsional or shear loading equivalent normal stress due to reversed axial loading total equivalent normal stress Maximum shear stress theory Maximum normal stress theory

mean or average bending stress Muhannad Al_Waily_Machines Systems Design mean or average bending stress Simple bending variable bending stress mean or average axial stress Axial Loading variable axial stress mean or average shear stress Simple torsion variable shear stress

Muhannad Al_Waily_Machines Systems Design Designing to Avoid Stress Concentrations (Methods of Reducing Stress Concentration)

Gear Forces Spur Gear Straight Tooth Bevel Gear Tangential force Muhannad Al_Waily_Machines Systems Design Gear Forces Spur Gear Straight Tooth Bevel Gear Tangential force Bevel Gear radial force Spiral Bevel Gear Helical Gear Tangential force Tangential force The pinion thrust force Separating force The gear thrust force Thrust force Worm Gearing Tangential force on the worm Tangential force on the worm gear The separating force

Muhannad Al_Waily_Machines Systems Design Tangential force Spur Gear radial force Tangential force If the pressure angle is measured in a plane perpendicular to the axis of the gear Separating force Thrust force Helical Gear Tangential force If the pressure angle is measured in a plane perpendicular to a tooth Separating force Thrust force

Direction of Thrust loading Straight Tooth Bevel Gear Muhannad Al_Waily_Machines Systems Design Direction of Thrust loading Bevel Gear Straight Tooth Bevel Gear The tangential force Spiral Bevel Gear The pinion thrust force The gear thrust force The tangential force The pinion thrust force The gear thrust force

Muhannad Al_Waily_Machines Systems Design (b) ( c ) (d) Muhannad Al_Waily_Machines Systems Design

Direction of Tangential forces on Worm and Worm gear Muhannad Al_Waily_Machines Systems Design Worm Gearing Tangential force on the worm Tangential force on the worm gear The separating force  = lead angle of the worm (which is the same as the helix angle of the worm gear) Direction of Tangential forces on Worm and Worm gear