Investigation on fatigue damage equivalence probability for the structure with similar fatigue hazardous detail parts

2021 ◽  
pp. 095440622110614
Author(s):  
Xiaohong Li ◽  
Qin Sun ◽  
Hongna Dui
Keyword(s):  
Fatigue Damage ◽  
Fatigue Failure ◽  
Failure Probability ◽  
Fatigue Cracking ◽  
Probability Method ◽  
Load Spectrum ◽  
Number Range ◽  
Acceleration Ratio ◽  
Load Spectra ◽  
Probability Criterion

Fatigue damage of a whole structure with multiple similar fatigue hazardous detail parts is unclear. This paper focuses on the concept of quantified fatigue damage for the structure with similar fatigue hazardous detail parts by using the probability method and fatigue failure probability of the severe load spectrum. The probability criterion and calculation method of equivalent damage with different load spectra were proposed. The fatigue life probability distribution of the severe load spectrum was analyzed, and the acceleration ratio was defined by the similar details number of fatigue cracking in combination with the fatigue failure probability characteristics of the severe load spectrum. The results show that there is good agreement between the similar details number range of fatigue cracking in two load spectra, which means they are considered to be equivalent. The ratio of the sum of two similar details number ranges is used as acceleration ratio to evaluate the severe load spectrum. The application of this study in the statistical sense of engineering structure fatigue failure is more convincing.

Probabilistic Properties of Fatigue Damage and an Equivalent Damage Simplification Model for Multi-Level Load Spectra

2016 ◽  
Vol 08 (02) ◽  
pp. 1650017 ◽  
Author(s):  
X. R. Liu ◽  
Q. Sun
Keyword(s):  
Fatigue Damage ◽  
Damage Model ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Test Results ◽  
Load Spectrum ◽  
Load Spectra ◽  
Multi Level ◽  
Load Sequence ◽  
Good Agreement

An equivalent fatigue damage simplification model for multi-level load spectrum is proposed. On the basis of the probabilistic fatigue damage model which takes load sequence effect into account and the constant amplitude fatigue tests, probabilistic properties of damage accumulated in one loading block are achieved quantitatively by statistical methods. The new simplification model can ensure that, for the original spectrum and simplified spectrum, the probabilistic properties of fatigue damage are almost the same. Fatigue tests for Al-alloy straight plates are performed to test the validity of the model. The test results are in good agreement with predicted results.

Analysis of Fatigue Reliability and Fatigue Life for a High Voltage Valve

2012 ◽  
Vol 479-481 ◽  
pp. 2072-2075
Author(s):  
Ji Kang Bo
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Failure Mode ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
High Voltage ◽  
Failure Probability ◽  
Fatigue Reliability ◽  
Actual Application ◽  
Working Principle

The high voltage valve bears repeated loads and impact in its working state. Fatigue failure or fatigue damage is the most common failure mode of high voltage valves. This work analyzes the working principle and working characteristics of a high voltage valve under a static rated load, and proposes the necessity of the fatigue analysis. The failure probability of the high voltage valve is presented and the service life of the entire valve obtained. To find the part prone to fail, the evaluation of the fatigue life of the high voltage valve is carried out. The fatigue life and safety factor of the high voltage valve is obtained. It is found that the edge joints are easy to fatigue failure, which provides a reference for the actual application and of maintenance the high voltage valve.

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.

A Study on the Main Parameters That Affects the Reliability of Fatigue Failure in a Marine Drilling Riser

2021 ◽  
Author(s):  
Bruno Luiz Barbosa das Chagas ◽  
Celso Kazuyuki Morooka
Keyword(s):  
Fatigue Damage ◽  
Fatigue Failure ◽  
Petroleum Reservoirs ◽  
Offshore Drilling ◽  
Deepwater Drilling ◽  
Sea Bottom ◽  
Reliability Method ◽  
Drilling Operations ◽  
Maritime Operations ◽  
Sea Currents

Abstract Advances in subsea exploration in the oceans to discover new petroleum reservoirs and sometimes different kind of minerals at the seabed in ultra deepwater, continuously introduce new challenges in offshore drilling operations. This motivates the development of increasingly safe maritime operations. In offshore petroleum, a marine drilling riser is the pipe that connects a wellhead at the sea bottom to a drillship at the sea surface, as an access to the wellbore. It serves as a guide for the drilling column with the drill bit and conductor to carry cuttings of rock coming from the wellbore drilling and its construction. Drilling riser is constantly exposed to adversity from the environment, such as waves, sea currents and platform motions induced by waves. These elements of the environment are prevailing factors that can cause a riser failure during deepwater drilling operations with undesirable consequences for the environment. In the present work, key parameters that influence the probability of fatigue failure in a marine drilling riser are identified, and a parametric evaluation with those parameters are carried out. Dynamic behavior of a riser is previously calculated and fatigue damage is estimated. Afterwards, the First Order Reliability Method (FORM) is applied to determine the probability of fatigue failure on the riser. Fundamentals of the procedure are described, and results are illustrated through the analysis for a typical riser in deepwater drilling operation. Parametric evaluations are done observing points considered as critical along the riser length, and looking to the sensitivity of key parameters in the process. For this study, the SN curve from API guidelines is applied and accumulated fatigue damage is estimated from simulations of the stress time series and applying the Palmgren-Miner’s rule. Finally, the influence of each parameter in the reliability of fatigue failure is verified and discussions given.

scholarly journals Compounding effects of sea level rise and fluvial flooding

2017 ◽  
Vol 114 (37) ◽  
pp. 9785-9790 ◽  
Author(s):  
Hamed R. Moftakhari ◽  
Gianfausto Salvadori ◽  
Amir AghaKouchak ◽  
Brett F. Sanders ◽  
Richard A. Matthew
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Hazard Assessment ◽  
Failure Probability ◽  
River Flow ◽  
Flood Hazard ◽  
High Tide ◽  
Probability Method ◽  
Flood Hazards ◽  
Flood Hazard Assessment

Sea level rise (SLR), a well-documented and urgent aspect of anthropogenic global warming, threatens population and assets located in low-lying coastal regions all around the world. Common flood hazard assessment practices typically account for one driver at a time (e.g., either fluvial flooding only or ocean flooding only), whereas coastal cities vulnerable to SLR are at risk for flooding from multiple drivers (e.g., extreme coastal high tide, storm surge, and river flow). Here, we propose a bivariate flood hazard assessment approach that accounts for compound flooding from river flow and coastal water level, and we show that a univariate approach may not appropriately characterize the flood hazard if there are compounding effects. Using copulas and bivariate dependence analysis, we also quantify the increases in failure probabilities for 2030 and 2050 caused by SLR under representative concentration pathways 4.5 and 8.5. Additionally, the increase in failure probability is shown to be strongly affected by compounding effects. The proposed failure probability method offers an innovative tool for assessing compounding flood hazards in a warming climate.

Experimental and Numerical Investigation of Torsion Fatigue of Bearing Steel

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
John A. R. Bomidi ◽  
Nick Weinzapfel ◽  
Trevor Slack ◽  
Sina Mobasher Moghaddam ◽  
Farshid Sadeghi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Normal Stress ◽  
Failure Mechanism ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Damage Mechanics ◽  
Damage Model ◽  
Bearing Steel ◽  
Fatigue Damage Accumulation

This paper presents the results of torsion fatigue of widely used bearing steels (through hardening with bainite, martensite heat treatments, and case hardened). An MTS torsion fatigue test rig (TFTR) was modified with custom mechanical grips and used to evaluate torsional fatigue life and failure mechanism of bearing steel specimen. Tests were conducted on the TFTR to determine the ultimate strength in shear (Sus) and stress cycle (S-N) results. Evaluation of the fatigue specimens in the high cycle regime indicates shear driven crack initiation followed by normal stress driven propagation, resulting in a helical crack pattern. A 3D finite element model was then developed to investigate fatigue damage in torsion specimen and replicate the observed fatigue failure mechanism for crack initiation and propagation. In the numerical model, continuum damage mechanics (CDM) were employed in a randomly generated 3D Voronoi tessellated mesh of the specimen to provide unstructured, nonplanar, interelement, and inter/transgranular paths for fatigue damage accumulation and crack evolution as observed in micrographs of specimen. Additionally, a new damage evolution procedure was implemented to capture the change in fatigue failure mechanism from shear to normal stress assisted crack growth. The progression of fatigue failure and the stress-life results obtained from the fatigue damage model are in good agreement with the experimental results. The fatigue damage model was also used to assess the influence of topological microstructure randomness accompanied by material inhomogeneity and defects on fatigue life dispersion.

Multi-Axial Fatigue Damage Models of Fiber Reinforced Composites

2004 ◽  
Author(s):  
N. H. Yang ◽  
H. Nayeb-Hashemi ◽  
A. Vaziri
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Multiaxial Fatigue ◽  
Loading Frequency ◽  
Reinforced Composites ◽  
Damage Models ◽  
Failure Models ◽  
Axial Fatigue

Fiberglass reinforced composites are extensively used in various structural components. In order to insure their structural integrity, their monotonic and fatigue properties under multiaxial stress fields must be understood. Combined in-phase tension/torsion loading is applied to [±45°]4 E-glass/epoxy composite tubes under monotonic and fatigue conditions to determine the effects of multiaxial loading on its failure. Various monotonic and fatigue damage criteria are proposed. These models considered failure mode (failure plane), the energy method and the effective stress-strain method. It is observed for the majority of experiments, the failure initiated at the outer lamina layer at 45° to the tube axis. A damage criterion for multiaxial monotonic loading is proposed considering both normal and shear stress contributions on the plane of failure. The experimental data show an excellent agreement with this proposed model for various loading conditions. Other failure models are currently under investigation utilizing the stresses and strains at the composite laminate as well as stress and strain at the outer lamina layer. Multiaxial fatigue failure models are proposed considering again the plane of failure. Since the plane of the failure is subjected to mean and cyclic stresses (shear and normal) and mean and cyclic strains (shear and normal), the fatigue damage models consider the contributions of these stresses and strains to the fatigue life of the composite tube. In addition to the fatigue damage model based on the plane of failure, a multi-axial fatigue failure model is proposed considering the mean and cyclic energy during fatigue experiments. The experimental data show a good correlation between the proposed damage parameters and fatigue life of specimens with some scatter of the data. Other fatigue failure models are currently under investigation considering the loading frequency and visco-elastic properties of the composite.

Mechanistic–empirical damage analysis and impacts of reduced tire pressure on thaw weakened flexible pavements using the AI and MEPDG models

2012 ◽  
Vol 39 (7) ◽  
pp. 812-823
Author(s):  
Leonnie Kavanagh ◽  
Ahmed Shalaby
Keyword(s):  
Fatigue Damage ◽  
Flexible Pavements ◽  
Fatigue Cracking ◽  
Flexible Pavement ◽  
T Test ◽  
Pavement Design ◽  
Damage Analysis ◽  
Confidence Limits ◽  
Tire Pressure ◽  
Design Guide

A damage analysis was conducted on a spring weight restricted flexible pavement to quantify the effects of reduced tire pressure on pavement life and to compare the damage predictions from the Asphalt Institute (AI) and the Mechanistic Empirical Pavement Design Guide (MEPDG) models. The models were used to predict the number of repetitions to fatigue and rutting failure at three maximum loads and at high and low tire pressures. Based on the results, the AI and MEPDG predictions were statistically different for both fatigue cracking and rutting damage, based on the t-test at 95% confidence limits. The AI model predicted 31% lower fatigue damage than the MEPDG, but 56% higher rutting damage. However, both models produced similar trends in predicting the relative effects of reduced tire pressure and load levels on pavement life. The methodology and results of the analysis are presented in this paper.

Reliability Model of Series and Parallel Systems under Imperfect Information

2012 ◽  
Vol 204-208 ◽  
pp. 4932-4935
Author(s):  
Bin Suo ◽  
Chao Zeng ◽  
Yong Sheng Cheng ◽  
Jun Li
Keyword(s):  
Failure Probability ◽  
Imperfect Information ◽  
Evidence Theory ◽  
Parallel Systems ◽  
Probability Method ◽  
Analysis Method ◽  
Interval Method ◽  
Additional Information ◽  
Interval Analysis Method ◽  
Reliability Calculation

In the situation that unit failure probability is imprecise when calculation the failure probability of system, classical probability method is not applicable, and the analysis result of interval method is coarse. To calculate the reliability of series and parallel systems in above situation, D-S evidence theory was used to represent the unit failure probability. Multi-sources information was fused, and belief and plausibility function were used to calculate the reliability of series and parallel systems by evidential reasoning. By this mean, lower and upper bounds of probability distribution of system failure probability were obtained. Simulation result shows that the proposed method is preferable to deal with the imprecise probability in reliability calculation, and can get additional information when compare with interval analysis method.

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