Theoretical Stress Concentration Factor for Spatial Helix Gear

This paper presents a method to calculate the theoretical stress concentration factor of spatial helix gears, combined with the numerical method by ANSYS FEA package and analytic method. The formula of theoretical stress concentration factor of driving tine is fitted numerically, which suits for the general application situation. Effects of the main parameters on theoretical stress concentration factor are analyzed respectively.

Notch Fracture Behavior of Cold-Rolled Ni3Al Foil

Notch effect on the fracture behavior of the Ni3Al foils has been investigated as a function of notch radius and depth. Tensile tests along the rolling direction showed that notch weakening occurred with introduce of notch. The effective stress concentration factor (ke) was much lower than the theoretical stress concentration factor (Kt), which was due to the local plastic deformation at the notch root. Cracks initiated along the shear band in the RD tension.

Computation of Theoretical Stress Concentration Factor of V Shaped Notch Tip

To obtain the crack life and value of the external load applied on the bar in the course of the bar precision cropping, the mathematic expression of the theoretical stress concentration factor in the tip of the V shaped notch containing its geometric parameters is built theoretically by analyzing the stress field distribution of V shaped notch tip and the stress intensity factor. The influences of the flare angle Φ, the radius at the groove bottom, and the groove depth d on the theoretical stress concentration factor are analyzed in detail and the obtained rational value is d/D=0.1 , s/D=0.015, Φ=90 in engineering practice. The analytical results show that the data obtained by the mathematic expression of theoretical stress concentration factor in the tip of the V shaped notch presented in the paper are coincident with the results of the corresponding parameters obtained by stress concentration manual in some extension.

Theoretical Stress Concentration Factors for Short Rectangular Plates With Centered Circular Holes

This work shows that the theoretical stress concentration factor depends on the length of the member in addition to the established other standard geometric parameters. In particular, the in-plane theoretical stress concentration factors for short rectangular plates with centered circular holes subjected to uniform tension are determined using the finite element method. It is shown that these factors can reach significantly larger values than the corresponding existing ones for long plates. The value of the transition length between long and short plates is computed and reported as well. Two new concepts are defined, short members and transition length.

Variation of Fatigue Notch Factor With Lifetime, Stress Ratio and Temperature

An understanding of the influence of various loading parameters on the fatigue notch factor Kf is important to the designer, who often relies exclusively on the limited fatigue data available in handbooks. The significance and limitations of Kf values so obtained are discussed in the light of geometry, fatigue lifetime, stress ratio, and temperature. Ultimately fatigue notch factor data in the literature are very limited, and often there is no recourse but to make use of the theoretical stress concentration factor Kt. The results of this procedure are usually very conservative. Handbook fatigue failure data were reexamined in order to determine the variation of Kf for a representative range of materials, including aluminum, steel, titanium and nickel alloys. Results are presented in the form of Kf over a wide range of notch and loading conditions. The results are interpreted and generalized in terms of stress concentration, and material mechanical and microstructural response.