Fatigue Life Estimation Procedures for the Endurance of a Cardiac Valve Prosthesis: Stress/Life and Damage-Tolerant Analyses

1986 ◽  
Vol 108 (2) ◽  
pp. 153-160 ◽  
Author(s):  
R. O. Ritchie ◽  
P. Lubock
Keyword(s):  
Fatigue Life ◽  
Cardiac Valve ◽  
Valve Prosthesis ◽  
Design Practice ◽  
Metal Fatigue ◽  
Life Estimation ◽  
Short Cracks ◽  
Fatigue Life Estimation ◽  
Developing Area ◽  
Damage Tolerant

Projected fatigue life analyses are performed to estimate the endurance of a cardiac valve prosthesis under physiological environmental and mechanical conditions. The analyses are conducted using both the classical stress-strain/life and the fracture mechanics-based damage-tolerant approaches, and provide estimates of expected life in terms of initial flaw sizes which may pre-exist in the metal prior to the valve entering service. The damage-tolerant analysis further is supplemented by consideration of the question of “short cracks,” which represents a developing area in metal fatigue research, not commonly applied to data in standard engineering design practice.

Fatigue Laws via Functional Equations

2008 ◽  
Author(s):  
Navendu Patil ◽  
Pradeep Mahadevan ◽  
Anindya Chatterjee
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Ad Hoc ◽  
Complex Loading ◽  
Metal Fatigue ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Many Sources

In routine industrial design, fatigue life estimation is largely based on S-N curves and ad hoc cycle counting algorithms used with Miner’s rule for predicting life under complex loading. However, there are well known deficiencies of the conventional approach. Of the many cumulative damage rules that have been proposed, Manson’s Double Linear Damage Rule (DLDR) has been the most successful. Here we follow up, through comparisons with experimental data from many sources, on a new approach to empirical fatigue life estimation (‘A Constructive Empirical Theory for Metal Fatigue Under Block Cyclic Loading’, Proceedings of the Royal Society A, in press). The basic modeling approach is first described: it depends on enforcing mathematical consistency between predictions of simple empirical models that include indeterminate functional forms, and published fatigue data from handbooks. This consistency is enforced through setting up and (with luck) solving a functional equation with three independent variables and six unknown functions. The model, after eliminating or identifying various parameters, retains three fitted parameters; for the experimental data available, one of these may be set to zero. On comparison against data from several different sources, with two fitted parameters, we find that our model works about as well as the DLDR and much better than Miner’s rule. We finally discuss some ways in which the model might be used, beyond the scope of the DLDR.

Load Spectrum Compiling and Fatigue Life Estimation of the Automobile Wheel Hub

2020 ◽  
Vol 13 ◽  
Author(s):  
Xintian Liu ◽  
Yang Qu ◽  
Xiaobing Yang ◽  
Yongfeng Shen
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Two Dimensional ◽  
Load Spectrum ◽  
One Dimensional ◽  
Life Estimation ◽  
Load Spectra ◽  
Fatigue Life Estimation ◽  
Program Load Spectrum ◽  
Program Load

Background:: In the process of high-speed driving, the wheel hub is constantly subjected to the impact load from the ground. Therefore, it is important to estimate the fatigue life of the hub in the design and production process. Objective:: This paper introduces a method to study the fatigue life of car hub based on the road load collected from test site. Methods:: Based on interval analysis, the distribution characteristics of load spectrum are analyzed. The fatigue life estimation of one - dimensional and two - dimensional load spectra is compared by compiling load spectra. Results:: According to the S-N curve cluster and the one-dimensional program load spectrum, the estimated range fatigue life of the hub is 397,100 km to 529,700 km. For unsymmetrical cyclic loading, each level means and amplitude of load were obtained through the Goodman fatigue empirical formula, and then according to S-N curve clusters in the upper and lower curves and two-dimensional program load spectrum, estimates the fatigue life of wheel hub of the interval is 329900 km to 435200 km, than one-dimensional load spectrum fatigue life was reduced by 16.9% - 17.8%. Conclusion:: This paper lays a foundation for the prediction of fatigue life and the bench test of fatigue durability of auto parts subjected to complex and variable random loads. At the same time, the research method can also be used to estimate the fatigue life of other bearing parts or high-speed moving parts and assemblies.

Notch fatigue life estimation of Ti-6Al-4V

2021 ◽  
Vol 120 ◽  
pp. 105098
Author(s):  
Camilla Ronchei ◽  
Sabrina Vantadori
Keyword(s):  
Fatigue Life ◽  
Life Estimation ◽  
Fatigue Life Estimation

An Investigation of Cyclic Transient Behavior and Implications on Fatigue Life Estimates

1997 ◽  
Vol 119 (2) ◽  
pp. 161-170 ◽  
Author(s):  
Yanyao Jiang ◽  
Peter Kurath
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Cyclic Hardening ◽  
Transient Behavior ◽  
Fatigue Tests ◽  
304 Stainless Steel ◽  
Deformation History ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Track Deformation

Current research focuses on proportional cyclic hardening and non-Massing behaviors. The interaction of these two hardenings can result in the traditionally observed overall softening, hardening or mixed behavior exhibited for fully reversed strain controlled fatigue tests. Proportional experiments were conducted with five materials, 304 stainless steel, normalized 1070 and 1045 steels, and 7075-T6 and 6061-T6 aluminum alloys. All the materials display similar trends, but the 304 stainless steel shows the most pronounced transient behavior and will be discussed in detail. Existing algorithms for this behavior are evaluated in light of the recent experiments, and refinements to the Armstrong-Frederick class of incremental plasticity models are proposed. Modifications implemented are more extensive than the traditional variation of yield stress, and a traditional strain based memory surface is utilized to track deformation history. Implications of the deformation characteristics with regard to fatigue life estimation, especially variable amplitude loading, will be examined. The high-low step loading is utilized to illustrate the effect of transient deformation on fatigue life estimation procedures, and their relationship to the observed and modeled deformation.

Fatigue Life Estimation of a Notched Shaft based on Combined Deviatoric Strain Amplitudes

2014 ◽  
Author(s):  
Luiz Henrique Bresser Cardoso de Mello ◽  
Fábio Comes de Castro
Keyword(s):  
Fatigue Life ◽  
Life Estimation ◽  
Fatigue Life Estimation

Numerical model for bending fatigue life estimation of carburized spur gears with consideration of the adjacent tooth effect

2021 ◽  
Vol 153 ◽  
pp. 106515
Author(s):  
Krešimir Vučković ◽  
Ivan Čular ◽  
Robert Mašović ◽  
Ivica Galić ◽  
Dragan Žeželj
Keyword(s):  
Fatigue Life ◽  
Numerical Model ◽  
Spur Gears ◽  
Bending Fatigue ◽  
Life Estimation ◽  
Adjacent Tooth ◽  
Fatigue Life Estimation
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