Application of a Reliability Method to Maintenance Strategy for Mechanical Components

2008 ◽  
Author(s):  
Young Ho Park ◽  
Iyad Hijazi ◽  
Jun Tang
Keyword(s):  
Decision Making ◽  
Fatigue Life ◽  
Fatigue Failure ◽  
Wide Band ◽  
Mean Value ◽  
Cumulative Damage ◽  
Damage Distribution ◽  
Reliability Method ◽  
The Mean ◽  
Mechanical Components

This paper presents 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. To evaluate probability function and the expected length of a failure cycle, approximated function forms were used.

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 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 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.

scholarly journals Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2738
Author(s):  
Roland Pawliczek ◽  
Tadeusz Lagoda
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Strain Curve ◽  
Mean Value ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Reference Case ◽  
Block Loading ◽  
The Mean ◽  
Mean Strain

The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

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.

Multiaxial Fatigue Life Assessment Method Based on the Mean Value of Modified Second Invariant of the Deviatoric Stress

2014 ◽  
Vol 224 ◽  
pp. 15-20
Author(s):  
Łukasz Pejkowski ◽  
Dariusz Skibicki
Keyword(s):  
Fatigue Life ◽  
Hydrostatic Stress ◽  
Assessment Method ◽  
Mean Value ◽  
Multiaxial Fatigue ◽  
Deviatoric Stress ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Fatigue Life Estimation ◽  
The Mean

Stress invariants approach to the multiaxial fatigue life estimation is generally based on the root mean square value of second invariant of the deviatoric stress amplitude and the value of hydrostatic stress. Such an approach omits a significant part of the information about multiaxial load history. It is particularly noticeable in case of non-proportional loadings, which lead to a reduction of fatigue life (i.e. [1–3]). In this work a new method based on the mean value of modified second invariant of the deviatoric stress has been presented.

Non-Probabilistic Reliability and Slope Stability Analysis

2014 ◽  
Vol 578-579 ◽  
pp. 1538-1541
Author(s):  
Huan Sheng Mu
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Reliability Index ◽  
Mean Value ◽  
Slope Stability Analysis ◽  
Performance Function ◽  
Interval Variables ◽  
Reliability Method ◽  
The Mean ◽  
The Difference

In the present paper, a non-probabilistic reliability method is proposed for slope stability analysis. Soil properties involved in non-probabilistic reliability analysis are viewed as random variables and represented by interval variables. The performance function for slope stability analysis is expressed as the difference between anti-sliding moment and driving moment. The non-probabilistic reliability index is defined as the ratio of the mean value of performance function to deviate. Three examples have illustrated the simplicity and applicability of the method. This method provides a new means for slope stability analysis.

scholarly journals EFEKTIVITAS PERSUASIF MELALUI NARASI DAN BUKTI STATISTIK TERHADAP PENGAMBILAN KEPUTUSAN MEMILIH PRODUK HANDPHONE

2017 ◽  
Vol 2 (1) ◽  
pp. 25-32
Author(s):  
Alwinansyah Farnas ◽  
Gumgum Gumelar
Keyword(s):  
Decision Making ◽  
Experimental Studies ◽  
Mean Value ◽  
Statistical Evidence ◽  
T Test ◽  
Test Results ◽  
Independent Test ◽  
The Mean ◽  
The Difference

The aim of this study was to determine whether there is a difference to the effectiveness of persuasion toward narrative and statistical evidence in making decisions selecting mobile products in adolescents. The study was conducted from September to January 2013. This study uses a method of controlled experimental studies labolatory. Analysis using t-test of the difference independent test samples from the test results obtained values F = 1461, p = 0231> 0.05 (not significant), meaning that there is no difference in the effectiveness of persuasion through narrative and statistical evidence on decision making in adolescents choose mobile products . Comparison of average (mean) persuasive narrative and persuasive statistical evidence obtained mean value 62.12 for the narrative and the mean value for the statistical proof of 60.06. Based on the results of this analysis rejected the hypothesis that there is no difference in the effectiveness of persuasion through narrative and statistical evidence for making decisions on choosing mobile products in teens. The implication of this research is to use both types of persuasive in influencing a person's decision-making in the absence of differences in effectiveness between the two.

Estimation of Probability of Fatigue Failure on Tubular Joints

2021 ◽  
Author(s):  
N. Lokesh ◽  
S. Nallayarasu ◽  
S. Karunanithi
Keyword(s):  
Fatigue Life ◽  
Failure Mode ◽  
Fatigue Failure ◽  
Limit State ◽  
Probabilistic Approach ◽  
Fatigue Crack Initiation ◽  
High Stress ◽  
State Function ◽  
Reliability Method

Abstract Fatigue is generally considered the most critical failure mode in mechanical and structural systems. Due to high-stress concentrations, welded joints represent the most common fatigue crack initiation in steel structures susceptible to fatigue. In India, especially in western offshore, there are about 300 platforms, and 50% of them have reached their design life but still operating due to existing oil and gas reserves. Fatigue prediction in offshore structures is an extremely complicated process involving many factors such as complicated geometry, material, loading, and environment. These uncertainties are modelled as random variables. The assessment of failure probabilities takes a basis to formulate a limit state function for the relevant failure mode and deterioration mechanisms. The fatigue failure assessment based on a simplified probabilistic approach using the application of reliability-based procedures such as the First Order Reliability Method (FORM) is a useful tool. In the simplified fatigue assessment method, the two-parameter Weibull distribution is used to model the long-term distribution of fatigue stresses. Reliability of tubular joint using known fatigue life is an important factor in decision making for life extension of aged platforms. The methodology adopted in this study uses the linear damage accumulation model of Palmgren-Miner, double slope S-N curve, and one-to-one transformation of the probability density functions of long-term stress range and uncertainties to obtain the probability of fatigue failure as a function of the service life from known fatigue life.

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.

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