An Efficient Methodology for Fatigue Reliability Analysis for Mechanical Components

2005 ◽  
Vol 128 (3) ◽  
pp. 293-297 ◽  
Author(s):  
Young Ho Park ◽  
Jun Tang
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Fatigue Failure ◽  
Failure Modes ◽  
Random Variable ◽  
Theoretical Background ◽  
Fatigue Reliability ◽  
Reliability Factor ◽  
Mechanical Components ◽  
Variable Problem

This paper presents an efficient methodology to solve a fatigue reliability problem. The fatigue failure mechanism and its reliability assessment must be treated as a rate process since, in general, the capacity of the component and material itself changes irreversibly with time. However, when fatigue life is predicted using the S-N curve and a damage summation scheme, the time dependent stress can be represented as several time-independent stress levels using the cycle counting approach. Since, in each counted stress cycle, the stress amplitude is constant, it becomes a random variable problem. The purpose of this study is to develop a methodology and algorithm to solve this converted random variable problem by combining the accumulated damage analysis with the first-order reliability analysis (FORM) to evaluate fatigue reliability. This task was tackled by determining a reliability factor using an inverse reliability analysis. The theoretical background and algorithm for the proposed approach to reliability analysis will be introduced based on fatigue failure modes of mechanical components. This paper will draw on an exploration of the ability to predict spectral fatigue life and to assess the corresponding reliability under a given dynamic environment. Next, the process for carrying out this integrated method of analysis will be explained. Use of the proposed methodology will allow for the prediction of mechanical component fatigue reliability according to different mission requirements.

An Efficient Methodology for Fatigue Reliability Analysis of Mechanical Components Based on the Stress-Life Prediction Approach

2003 ◽  
Author(s):  
Jun Tang ◽  
Young Ho Park
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Life Prediction ◽  
Failure Modes ◽  
Theoretical Background ◽  
Fatigue Reliability ◽  
Integrated Method ◽  
Reliability Method ◽  
Mechanical Components ◽  
Prediction Approach

An efficient methodology for fatigue reliability assessment and its corresponding fatigue life prediction of mechanical components using the First-Order Reliability Method (FORM) is developed in this paper. Using the proposed method, a family of reliability defined S-N curves, called R-S-N curves, can be constructed. In exploring the ability to predict spectral fatigue life and assessing the corresponding reliability under a specified dynamics environment, the theoretical background and the algorithm of a simple approach for reliability analysis will first be introduced based on fatigue failure modes of mechanical components. It will then be explained how this integrated method will carry out the spectral fatigue damage and failure reliability analysis. By using this proposed methodology, mechanical component fatigue reliability can be predicted according to different mission requirements.

An Efficient Algorithm Based on First Order Reliability Method for Fatigue Reliability Analysis of Mechanical Components

2002 ◽  
Author(s):  
Jun Tang ◽  
Young Ho Park
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Search Algorithm ◽  
Strain History ◽  
Fatigue Reliability ◽  
First Order Reliability Method ◽  
Reliability Factor ◽  
First Order ◽  
Reliability Method ◽  
Mechanical Components

The method for fatigue reliability analysis of mechanical components using the First-Order Reliability Method (FORM) reconciles accuracy and efficiency requirements for random process reliability problems under fatigue failure. However, the algorithm for solving FORM is still complex and time consuming. In this paper, the FORM that utilizes an efficient search algorithm is proposed for reliability assessment of the strain-based fatigue life. Using the proposed method, a family of reliability-defined ε-Nf curves, referred to as R-ε-Nf curves, is constructed. An empirical mean stress modified strain-life equation is also used as the performance function. The primary focus of this effort has been the implementation of the new algorithm of FORM to define reliability factors used in modifying the conventional ε-Nf curve to create a family of R-ε-Nf curves, based on the unique reliability factor rule. The proposed method employs the inverse FORM algorithm to achieve computational results, including reliability and the corresponding fatigue life. The method enables the application of fatigue life design for a given cyclic stress and/or strain history. A numerical example is presented to demonstrate the proposed method.

Optimum Replacement Interval for Mechanical Components Based on Fatigue Reliability

2006 ◽  
Vol 129 (4) ◽  
pp. 683-688 ◽  
Author(s):  
Young H. Park ◽  
Jun Tang
Keyword(s):  
Decision Making ◽  
Fatigue Life ◽  
Fatigue Failure ◽  
Wide Band ◽  
Mean Value ◽  
Cumulative Damage ◽  
Fatigue Reliability ◽  
Damage Distribution ◽  
Mean And Variance ◽  
Mechanical Components

This paper introduces a maintenance decision-making strategy in the general area of replacement and reliability of mechanical components. The decision-making strategy involves the optimization of replacement interval calculated from fatigue failure of mechanical components. The proposed approach is based on the cumulative damage distribution function for evaluating mean fatigue life. Using this approach, the analytical expressions for mean and variance of the cumulative damage distribution under both stationary narrow-band and stationary wide-band random process are provided. The mean value and variance of fatigue life distribution are then evaluated to determine the optimal replacement intervals under fatigue failure. A practical example is presented to demonstrate the application of the present method.

Fatigue Reliability Analysis of Turbine of Turbocharger Based on the Endurance Test Profile of Engine

2012 ◽  
Vol 215-216 ◽  
pp. 750-753
Author(s):  
Wang Zheng ◽  
Wei Dong Xing ◽  
A Na Wang ◽  
Li Xin
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Failure Mode ◽  
Fatigue Failure ◽  
Fatigue Reliability ◽  
Endurance Test ◽  
Cycle Number ◽  
Operating Modes ◽  
Critical Location ◽  
The Relationship

For the fatigue failure mode of turbine of turbocharger for vehicle application, the method for fatigue reliability analysis and fatigue life prediction of turbine is studied based on the endurance test profile of engine. Firstly, the critical location of turbocharger turbine with fatigue failure mode is determined. Then, the fatigue stress process of turbine is calculated according to the main operating modes consisted of the endurance test profile of engine. The fatigue strength of critical location of turbine with fatigue failure mode is studied through the fatigue test of imitation specimen, and the relationship between the fatigue life of turbine and stress is developed. Further, according to the endurance test profile of engine, the reliability model of turbine with fatigue failure mode is developed, and the rule that the reliability of turbine with fatigue failure mode changes as the cycle number of endurance test of engine is studied. Finally, the method for determining the reliable fatigue life of turbine is proposed.

Fatigue Reliability Based Optimal Replacement Decision Based on First Order Reliability Method

2005 ◽  
Author(s):  
Jun Tang ◽  
Edwin Hardee ◽  
Young H. Park
Keyword(s):  
Decision Making ◽  
Fatigue Failure ◽  
Operating Costs ◽  
Fatigue Reliability ◽  
Reliability Factor ◽  
First Order ◽  
Optimal Replacement ◽  
Inverse Reliability Analysis ◽  
Reliability Method ◽  
Mechanical Components

This paper introduces a maintenance decision-making strategy in the general area of the replacement and reliability of mechanical components. The decision-making strategy involves the optimization of the replacement interval based on fatigue failure of mechanical components. Fatigue reliabilities of a component under random cyclic loading need to be evaluated to determine the optimal replacement intervals under fatigue failure. This task is undertaken by determining a reliability factor using an inverse reliability analysis. A reliability-defined ε-N curve (R-ε-Nf curve) can be generated for an empirical ε-N relationship and a “unique” reliability factor by modifying the nominal ε-Nf curve using reliability factors for an assigned reliability. A family of R-ε-Nf curves, which includes the conventional ε-Nf curve, can then be obtained. Hence, fatigue life under specified reliability or reliability based on mission life can be predicted using these curves. This method can efficiently determine replacement intervals for components whose operating costs increase with use and replacement intervals for components subject to failure induced by random process. An example is presented to demonstrate the application of the present method.

Calculation Error Analysis on the Strain Fatigue Life Predication Formula of Manson-Coffinn and Damage Stain Model

2011 ◽  
Vol 197-198 ◽  
pp. 1599-1603
Author(s):  
Zhen Wei Wang ◽  
Ping An Du ◽  
Ya Ting Yu
Keyword(s):  
Fatigue Life ◽  
Error Analysis ◽  
Fatigue Failure ◽  
High Speed ◽  
Production Cost ◽  
Calculation Error ◽  
Mechanical Components ◽  
Strain Model ◽  
Engine Crankshaft

Mechanical components are subjected heavy alternate load in industries, such as engine crankshaft, wheel axle, etc. The fatigue failure happens after a long work loading, which affects the production cost, safe and time. So the fatigue life predication is fundamental for the mechanical components design. Especially, it is very important for heavy, high-speed machinery. In this paper, both main fatigue life predication formulas are introduced briefly, including Manson-Coffinn formula and Damage strain model. Then, shortages of above life predication formulas are pointed out, and coefficients are explained in detail. Further calculation error analysis is conducted on the basis of experiments on 16 materials. Results show that above life predication formulas lack calculation accuracy. Finally, it is pointed out that coefficients of fatigue life predication formulas are dependent of material performance. So it is unreliable that coefficients are constants for Manson-Coffin and Damage strain model.

Fatigue Reliability Based Optimal Replacement Decision of Mechanical Components

2004 ◽  
Author(s):  
Jun Tang ◽  
Young Ho Park
Keyword(s):  
Decision Making ◽  
Fatigue Life ◽  
Random Process ◽  
Fatigue Failure ◽  
Cumulative Damage ◽  
Analytical Models ◽  
Damage Distribution ◽  
Optimal Replacement ◽  
The Mean ◽  
Mechanical Components

This paper introduces a maintenance decision-making strategy in the general area of replacement and reliability of mechanical components. The decision-making strategy involves the optimization of replacement interval based on fatigue failure of mechanical components. This new approach is based on the cumulative damage distribution function for evaluating mean fatigue life. By using the approach, the analytical expressions for the mean and the variance of the cumulative damage distribution under both stationary narrow-band and stationary wide-band random process are provided. The mean value and variance of the fatigue life distribution are thus evaluated to determine the optimal replacement intervals under fatigue failure. An algorithm of evaluating the mean and standard deviation of fatigue life is also presented. Therefore, the reliability of a component under random cyclic loading for a specified duration is quantified accordingly. Even though the new method introduces a great deal of complexity in the analytical models, this method can efficiently determine replacement intervals for component whose operating costs increases with use and replacement intervals for component subject to failure induced by the random process. An example is presented to demonstrate the application of the present method.

Fatigue Reliability Analysis Including Super Long Life Regime

2010 ◽  
Vol 118-120 ◽  
pp. 17-26 ◽  
Author(s):  
Yong Xiang Zhao
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Life Prediction ◽  
Reliability Assessment ◽  
Cyclic Stress ◽  
Fatigue Life Prediction ◽  
Fatigue Reliability ◽  
Stress Strain ◽  
Structural Fatigue ◽  
Long Life

For an engineering structure with an actual fatigue life over that corresponding to a so-called fatigue limit, appropriate reliability assessment and fatigue life prediction are essential for developing the structure and sustaining its high quality in service. Basic clues are explored. A competition fatigue initial mechanism is shown to provide a requirement of material primary quality management. Affordable deduced material and structural probabilistic S-N curves are presented by fitting into material mid-and-long life S-N data and fatigue limits and, then, comparing to structural fatigue limits. Random cyclic stress-strain relations are depicted for constructing random stressing history of structures. Reliability assessment and fatigue life prediction are established to synthetically consider the interference of applied stresses deduced from the random cyclic stress-strain relations and capacity strengths derived from the structural S-N relations with an expected life. Affordable and appropriate method has been then developed to realize the reliability assessment and fatigue life prediction including the super long life regime. Availability of the present method has been indicated through a reliability analysis to the velocity related reliabilities and fatigue lives of a railway axle.

The Effect of Soil on the Structural Response and Fatigue Life of Free Span for Submarine Pipeline

2015 ◽  
Author(s):  
Jie Dong ◽  
Chen Xuedong ◽  
Bing Wang ◽  
Weihe Guan ◽  
Tiecheng Yang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Flow Velocity ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Failure Modes ◽  
Structural Response ◽  
Submarine Pipeline ◽  
Velocity Data ◽  
Measured Flow ◽  
Stiffness And Damping

Free span resulting from unevenness of seabed or scour of current is a dangerous status for submarine pipeline. Fatigue failure caused by vortex induced vibration (VIV) is one of the main failure modes for free span. Because of the contact between soil and pipeline, the effect of soil must be considered for the fatigue analysis of free span. In this paper, aimed at one in-service submarine pipeline, the research on the VIV response of free span was investigated considering the effect of stiffness and damping of soil. Furthermore, fatigue damage and fatigue life of free span were evaluated based on the actual measured flow velocity data varied with time. The analysis results have provided support for the maintenance of free span for the submarine pipeline.

Propagation of Contact Fatigue From Surface and Subsurface Origins

1966 ◽  
Vol 88 (3) ◽  
pp. 624-635 ◽  
Author(s):  
W. E. Littmann ◽  
R. L. Widner
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Failure ◽  
Contact Stress ◽  
Environmental Conditions ◽  
Failure Modes ◽  
Contact Fatigue ◽  
Initiation And Propagation ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Fatigue life of tapered roller bearings and other elements subject to cyclic contact stress reflects the fatigue strength of the selected material under given environmental conditions. The various modes of contact-fatigue failure have been classified according to their appearance and the factors which promote their initiation and propagation. Illustrations of the various failure modes include rig test specimens and bearings representing normal catalog-rated life under laboratory and application environments. Evidence is presented for the propagation of contact fatigue from surface and subsurface origins.

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