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

1986 ◽  
Vol 108 (2) ◽  
pp. 179-185 ◽  
Author(s):  
Avraham Berkovits
Keyword(s):  
Stress Concentration ◽  
Nickel Alloys ◽  
Stress Ratio ◽  
Fatigue Lifetime ◽  
Failure Data ◽  
Wide Range ◽  
Fatigue Notch Factor ◽  
Factor Data ◽  
Theoretical Stress ◽  
Theoretical Stress Concentration Factor

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.

Computation of Theoretical Stress Concentration Factor of V Shaped Notch Tip

2012 ◽  
Vol 152-154 ◽  
pp. 765-769
Author(s):  
Li Jun Zhang ◽  
Jie Qiong Xue ◽  
Yong Rui Zhao ◽  
Heng Fu Xiang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Groove Depth ◽  
Engineering Practice ◽  
Notch Tip ◽  
Theoretical Stress ◽  
Theoretical Stress Concentration Factor

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

1999 ◽  
Vol 124 (1) ◽  
pp. 126-128 ◽  
Author(s):  
N. Troyani ◽  
C. Gomes ◽  
G. Sterlacci
Keyword(s):  
Stress Concentration ◽  
Rectangular Plates ◽  
The Finite Element Method ◽  
New Concepts ◽  
Circular Holes ◽  
Transition Length ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Theoretical Stress ◽  
Theoretical Stress Concentration Factor

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.

Theoretical Stress Concentration Factor for Spatial Helix Gear

2014 ◽  
Vol 551 ◽  
pp. 90-95 ◽  
Author(s):  
Zhen Chen ◽  
Yang Zhi Chen ◽  
En Yi He
Keyword(s):  
Stress Concentration ◽  
Numerical Method ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Analytic Method ◽  
General Application ◽  
Theoretical Stress ◽  
Theoretical Stress Concentration Factor

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

2012 ◽  
Vol 602-604 ◽  
pp. 2201-2204
Author(s):  
Chuan Yong Cui ◽  
Toshiyuki Hirano
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Fracture Behavior ◽  
Notch Root ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Theoretical Stress ◽  
Local Plastic Deformation ◽  
Theoretical Stress Concentration Factor

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.

Calculation of plasma centrifugal spraying parameters of fine granules of heat-resistant nickel alloys

2020 ◽  
pp. 471-474
Author(s):  
M.G. Yagodin ◽  
E.I. Starovoytenko
Keyword(s):  
Powder Metallurgy ◽  
Nickel Alloys ◽  
Dynamic Pressure ◽  
Calculated Data ◽  
Powder Size ◽  
Metal Powders ◽  
Heat Resistant ◽  
Gas Dynamic ◽  
Spraying Parameters ◽  
Wide Range

The equipment for the production of wide range of metal powders purposed for powder metallurgy is described. The possibility for producing of powders by the plasma centrifugal spraying is considered taking into account the gas dynamic pressure. The calculated data on the powder size for different materials are given.

Application of the R-Curve Concept to Fatigue Crack Growth

1978 ◽  
Vol 100 (4) ◽  
pp. 416-420 ◽  
Author(s):  
D. P. Wilhem ◽  
M. M. Ratwani
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Extension ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Crack Growth Resistance ◽  
Resistance Curve ◽  
Cyclic Stress Ratio ◽  
Wide Range

Crack growth resistance for both static (rising load) and for cyclic fatigue crack growth has been shown to be a continuous function over a range of 0.1 μm to 10 cm in crack extension for 2024-T3 aluminum. Crack growth resistance to each fatigue cycle of crack extension is shown to approach the materials ordinary undirectional static crack resistance value when the cyclic stress ratio is zero. The fatigue crack extension is averaged over many cycles and is correlated with the maximum value of the crack tip stress intensity, Kmax. A linear plot of crack growth resistance for fatigue and static loading data shows similar effects of thickness, stress ratio, and other parameters. The effect of cyclic stress ratio on crack growth resistance for 2219 aluminum indicates the magnitude of differences in resistance when plotted to a linear scale. Prediction of many of these trends is possible using one of several available crack growth data correlating techniques. It appears that a unique resistance curve, dependent on material, crack orientation, thickness, and stress/physical environment, can be developed for crack extensions as small as 0.076 μm (3 μ inches). This wide range, crack growth resistance curve is seen of immense potential for use in both fatigue and fracture studies.

Management of Complex Loading Histories for Use in Probabilistic Creep-Fatigue Damage Assessments

2018 ◽  
Author(s):  
N. A. Zentuti ◽  
J. D. Booker ◽  
R. A. W. Bradford ◽  
C. E. Truman
Keyword(s):  
Fatigue Damage ◽  
Input Parameter ◽  
Three Dimensional ◽  
Complex Loading ◽  
Fe Model ◽  
Plant Component ◽  
Fatigue Lifetime ◽  
Wide Range ◽  
Stress Components ◽  
Creep Fatigue

An approach is outlined for the treatment of stresses in complex three-dimensional components for the purpose of conducting probabilistic creep-fatigue lifetime assessments. For conventional deterministic assessments, the stress state in a plant component is found using thermal and mechanical (elastic) finite element (FE) models. Key inputs are typically steam temperatures and pressures, with the three principal stress components (PSCs) at the assessment location(s) being the outputs. This paper presents an approach which was developed based on application experience with a tube-plate ligament (TPL) component, for which historical data was available. Though both transient as well as steady-state conditions can have large contributions towards the creep-fatigue damage, this work is mainly concerned with the latter. In a probabilistic assessment, the aim of this approach is to replace time intensive FE runs with a predictive model to approximate stresses at various assessment locations. This is achieved by firstly modelling a wide range of typical loading conditions using FE models to obtain the desire stresses. Based on the results from these FE runs, a probability map is produced and input(s)-output(s) functions are fitted (either using a Response Surface Method or Linear Regression). These models are thereafter used to predict stresses as functions of the input parameter(s) directly. This mitigates running an FE model for every probabilistic trial (of which there typically may be more than 104), an approach which would be computationally prohibitive.

Sign in / Sign up

Export Citation Format

Share Document