Fatigue life prediction under random loading using distributional stress-life relationship

1999 ◽  
Author(s):  
Jiliang Zhang ◽  
Dimitri Kececioglu
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Random Loading

Application of a Multiaxial Fatigue Criterion for the Evaluation of Life of Gears of Complex Geometry

2003 ◽  
Author(s):  
Leonardo Borgianni ◽  
Paola Forte ◽  
Luigi Marchi
Keyword(s):  
Fatigue Life ◽  
Stress State ◽  
Life Prediction ◽  
Complex Geometry ◽  
Biaxial Stress ◽  
Fatigue Life Prediction ◽  
Random Loading ◽  
Complex Load ◽  
Biaxial Stress State ◽  
Principal Axes

Gears can show significant biaxial stress state at tooth root fillet, due to the way they are loaded and their particular geometry. This biaxial stress state can show a significant variability in principal axes during meshing. Moreover loads may have non predictable components that can be evaluated with the aid of recorded data from complex spectra. In these conditions, commonly adopted approaches for fatigue evaluation may be unsuitable for a reliable fatigue life prediction. This work is aimed at discussing a computer implementation of a fatigue life prediction method suitable for multiaxial stress states and constant amplitude or random loading. For random loading a counting procedure to extract cycles from complex load histories is discussed. This method, proposed by Vidal et al., is based on the r.m.s. value of a damage indicator over all the planes through the point where the fatigue life calculation is made. Miner’s rule is used for the evaluation of the overall damage. The whole fatigue life of the component is evaluated in terms of the numbers of repetitions of the loading block. FEM data are used to evaluate stresses under load. The implementation was validated using test data found in the technical literature. Examples of applications to gears are finally discussed.

Fatigue life-based reliability assessment of a heavy vehicle leaf spring

2019 ◽  
Vol 10 (5) ◽  
pp. 726-736
Author(s):  
Lennie Abdullah ◽  
Salvinder Singh Karam Singh ◽  
Abdul Hadi Azman ◽  
Shahrum Abdullah ◽  
Ahmad Kamal Ariffin Mohd Ihsan ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Reliability Assessment ◽  
Gumbel Distribution ◽  
High Amplitude ◽  
Fatigue Life Prediction ◽  
Leaf Spring ◽  
Heavy Vehicle ◽  
Random Loading ◽  
Content Type

Purpose This study aims to determine the reliability assessment based on the predicted fatigue life of leaf spring under random strain loading. Design/methodology/approach Random loading data were extracted from three various road conditions at 200 Hz using a strain gauge for a duration of 100 s. The fatigue life was predicted using strain-life approaches of Coffin–Manson, Morrow and Smith–Watson–Topper (SWT) models. Findings The leaf spring had the highest fatigue life of 1,544 cycle/block under highway data compared uphill (1,299 cycle/block) and downhill (1,008 cycle/block) data. Besides that, the statistical properties of kurtosis showed that uphill data were the highest at 3.81 resulted in the presence of high amplitude in the strain loading data. For fatigue life-based reliability assessment, the SWT model provided a narrower shape compared to the Coffin–Manson and Morrow models using the Gumbel distribution. The SWT model had the lowest mean cycle to failure of 1,250 cycle/block followed by Morrow model (1,317 cycle/block) and the Coffin–Manson model (1,429 cycle/block). The SWT model considers the mean stress effects by interpreting the strain energy density that will influence the reliability assessment. Research limitations/implications The reliability assessment based on fatigue life prediction is conducted using the Gumbel distribution to investigate the behaviour of fatigue random loading, where most previous studies had concentrated on a Weibull distribution on random data. Originality/value Thus, this study proposes that the Gumbel distribution is suitable for analysing the reliability of random loading data in assessing with the fatigue life prediction of a heavy vehicle leaf spring.

Fatigue Life Prediction for Caliper Guide Pin under Random Vibrational Loading

2014 ◽  
Vol 891-892 ◽  
pp. 1755-1760
Author(s):  
Bilal I. Antar ◽  
Hong Tae Kang
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Process Variations ◽  
Fatigue Life Prediction ◽  
System Level ◽  
Random Loading ◽  
Predictive Tool ◽  
Test Fixture ◽  
Vibrational Loading ◽  
Failure Location

A fatigue life prediction tool was developed for caliper guide pins under random vibrational loading. The Pie-Slice model was designed to provide detailed information about the failure location, orientation, and damage magnitude. A component test fixture was developed to determine the strain-life curve for a given guide pin design. Statistical analysis was conducted to insure the repeatability of the failure mode and the robustness of the setup. Weibull analysis was performed to the measured guide pin strain-life in order to insure that the developed strain-life data to insure that developed strain-life curve will account for all the manufacturing process variations, from a component, assembly, and a system level to a certain level of reliability and confidence. Rainflow cycle count was used to bin the damaging and non-damaging cycles based on their stain level. Fatigue life calculation was performed using the Smith-Watson-Topper strain-life approach. The predictive tool was able to accurately estimate the cumulative fatigue damage for guide pins under random loading conditions. The Pie-Slice model was also able to predict the failure location and orientation of a crack, as well as the damage magnitude. Both tools were validated using a pre-designed random block-load sequence at constant amplitude..

Algorithms for multiaxial cycle counting method and fatigue life prediction based on the weight function critical plane under random loading

2019 ◽  
Vol 28 (9) ◽  
pp. 1367-1392 ◽  
Author(s):  
Xiao-Wei Wang ◽  
De-Guang Shang ◽  
Yu-Juan Sun ◽  
Xiao-Dong Liu
Keyword(s):  
Experimental Data ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Weight Function ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Counting Method ◽  
Critical Plane ◽  
Random Loading

Based on the critical plane determined by the weight function method, two algorithms for multiaxial cycle counting method are proposed by modifying the rainflow and range cycle counting methods. The proposed two algorithms can be applied to multiaxial random loading, and be suitable to any critical plane-based fatigue life prediction models, since the counted cycles or reversals are represented by the start time and end time. The proposed two algorithms are used to predict multiaxial fatigue life by the experimental data of 7075-T651 aluminum alloy, En15R steel and 7050-T7451 aluminum alloy conducted under multiaxial random loading in both high-cycle and low-cycle fatigue region. The life prediction results are in good agreement with the experimental data.

Total fatigue life prediction for welded joints based on initial and equivalent crack size determination

2017 ◽  
Vol 27 (7) ◽  
pp. 1084-1104 ◽  
Author(s):  
Xiaoqiang Zhang ◽  
Huiying Gao ◽  
Hong-Zhong Huang
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
Model Uncertainty ◽  
Life Prediction ◽  
Crack Size ◽  
Initial Crack ◽  
Calculation Model ◽  
Fatigue Life Prediction ◽  
Random Loading ◽  
Calculation Process

When the linear elastic fracture mechanics-based approaches are used to predict the fatigue life of welded joints, initial crack size is a key point, which eventually affects the accuracy of total fatigue life prediction. Meanwhile, the life prediction process under random loading is complicated. In this paper, a novel method is proposed to determine the initial crack size, which is based on the results of back-extrapolation approach. The proposed method expresses the stress intensity factor, and the boundary between crack initiation and propagation period is taken into consideration. Based on the proposed method, deterministic total fatigue life can be obtained with fewer tests and less cost. In addition, the concept of equivalent crack size and its calculation model are proposed to reduce the complexity of the calculation process of fatigue life prediction under random loading, and model uncertainty is included into the prediction model of probabilistic fatigue life based on equivalent crack size. It is feasible, which has been verified, to take the influence of stress level into account when determining the initial crack size. Meanwhile, the proposal of equivalent crack size simplifies the calculation process of probabilistic fatigue life, and the consideration of model uncertainty is more conducive to assess the safety and reliability of the materials or structures.

Sign in / Sign up

Export Citation Format

Share Document