Variable Amplitude Fatigue Life Estimation Models

1982 ◽  
Author(s):  
Darrell Socie
Keyword(s):  
Fatigue Life ◽  
Variable Amplitude ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Variable Amplitude Fatigue ◽  
Estimation Models

Identification of Variable Amplitude Fatigue Loading Based on Bivariate Probability Mass Functions

2019 ◽  
Author(s):  
Hewenxuan Li ◽  
David Chelidze
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Temporal Dynamics ◽  
Variable Amplitude ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Time Histories ◽  
Probability Mass ◽  
Bivariate Probability ◽  
Mass Functions

Abstract Fatigue life estimation under variable amplitude (VA) loading remains one of the major unresolved engineering problems. When engineering structures experience VA loading, the corresponding load at the crack front will be highly non-stationary. Under such conditions, the load interaction effects greatly affect fatigue crack propagation rate and can cause significant variation in the corresponding fatigue life. Existing characterization methods focus on single overload effect and their extensions to sequence of overloads which does not reflect the irregularity of the realistic loading. In this paper, numerical simulations were used to compare the fatigue life under various synthetic load time histories. The resulting time to failure estimation, concerning statistically and spectrally identical deterministic loads and their stochastic surrogates, exhibits drastic difference which reflects the corresponding differences in the temporal structure of the loads, which are not differentiated by their linear characteristics. This indicates that the temporal dynamics of the load time histories have considerable influence on fatigue crack propagation and fracture. In order to differentiate temporal dynamics of the synthetic loading, new bivariate probability mass functions (BPMFs) are proposed. They can capture and preserve the underlying temporal dynamics of locally non-stationary variable amplitude load-time histories with identical linear statistics. And qualitative explanations of the potential of this proposed method for fatigue life estimation under VA loading are discussed.

scholarly journals Influence of Selected Multiaxial Stress Paths on Fatigue Estimation under Variable Amplitude Loading

2021 ◽  
Author(s):  
Jan Papuga ◽  
Matúš Margetin ◽  
Vladimír Chmelko
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Multiaxial Loading ◽  
Cycle Fatigue ◽  
Variable Amplitude ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Shift Effect ◽  
Fatigue Estimation

The paper discusses solutions used for estimating fatigue life under variable amplitude multiaxial loading in the high-cycle fatigue domain. Various concurring effects are treated, and their proposed solutions are commented upon. The focus is on the categories of the phase shift effect and of cycle counting. It is concluded that the available experimental data are not sufficient to substantiate a clear decision to follow a definite algorithm. An example of own new experimental data is provided, and the fatigue life estimation run to highlight some more points open for discussion.

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.

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