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 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 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.

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.

scholarly journals Fatigue Reliability Analysis Method of Reactor Structure Considering Cumulative Effect of Irradiation

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 801
Author(s):  
Bo Sun ◽  
Junlin Pan ◽  
Zili Wang ◽  
Yi Ren ◽  
Dariusz Mazurkiewicz ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Life Prediction ◽  
Cumulative Effect ◽  
Neutron Dose ◽  
Design Parameters ◽  
Performance Parameters ◽  
Analysis Method ◽  
Fatigue Reliability ◽  
Rate Of Increase

The influence of irradiation should be considered in fatigue reliability analyses of reactor structures under irradiation conditions. In this study, the effects of irradiation hardening and irradiation embrittlement on fatigue performance parameters were quantified and a fatigue life prediction model was developed. Based on this model, which takes into account the cumulative effect of a neutron dose, the total fatigue damage was calculated according to Miner’s linear cumulative damage law, and the reliability analysis was carried out using the Monte Carlo simulation method. The case results show that the fatigue life acquired by taking into account the cumulative effect of irradiation was reduced by 24.3% compared with that acquired without considering the irradiation effect. Irradiation led to the increase of the fatigue life at low strains and its decrease at high strains, which is in accordance with the findings of an irradiation fatigue test. The rate of increase in the fatigue life decreased gradually with the increase of the neutron dose. The irradiation performance parameters had a small influence on fatigue reliability, while the fatigue strength coefficient and the elastic modulus had a great influence on the fatigue reliability. Compared with the current method, which uses a high safety factor to determine design parameters, a fatigue reliability analysis method taking into account the cumulative effect of irradiation could be more accurate in the reliability analysis and life prediction of reactor structures.

Dynamic Response and Fatigue Reliability Analysis of Marine Riser Under Random Loads

2007 ◽  
Author(s):  
Rizwan A. Khan ◽  
Suhail Ahmad
Keyword(s):  
Reliability Analysis ◽  
Failure Modes ◽  
Oil Field ◽  
Environmental Damage ◽  
State Function ◽  
Unstable Fracture ◽  
Random Waves ◽  
Fatigue Reliability ◽  
Marine Riser ◽  
Reliability Method

Marine riser is a major component of offshore drilling and productions systems that are either fixed or floating. Since, a marine riser is intended to remain in station for the productive life of an oil field; it will be exposed to wide variety of hazards, with the potential for environmental damage, structural failure or damage to the material. As part of the design process, there are requirements of structural strength based on criteria referring to failure modes, such as rupture by over loading, fatigue failures, buckling or unstable fracture. 3D Nonlinear dynamic analysis of riser is carried out in the time domain using finite element solver ABAQUS/Aqua. The response histories so obtained are employed for the study of fatigue and fracture reliability analysis of riser under random waves and random waves together-with vessel motion. In the present study application of structural concepts for the evaluation of the fatigue resistance of marine risers, including reliability techniques has been presented. The limit state function has been established for cumulative fatigue damage using S-N curve approach and fracture mechanics approaches considering number of parameters, random in nature. Reliability methods deal with the uncertain nature of loads, resistance etc. and lead to prediction of the failure and a rational measure of the safety coefficient. Response surface method (RSM) in conjunction with First Order Reliability Method (FORM) has been used for reliability estimation. The results are compared with Monte Carlo simulation method. The design point important for the probabilistic design is located on the failure surface. The effects of the uncertainties in various random variables on riser fatigue reliability are highlighted.

Cumulative Damage-Based Stiffness Reliability Analysis of the Stochastic Structural System

2006 ◽  
Vol 324-325 ◽  
pp. 219-222
Author(s):  
Xin Chi Yan ◽  
Wei Tao Zhao
Keyword(s):  
Elastic Modulus ◽  
Service Life ◽  
Reliability Analysis ◽  
Reliability Index ◽  
Failure Modes ◽  
Cumulative Damage ◽  
Material Strength ◽  
Structural System ◽  
Fatigue Reliability ◽  
Reliability Method

Based on the understanding of passive impact of crack induced by fatigue load on ultimate stress and the relation of material strength and elastic modulus, the paper gives expression of residual elastic modulus with the form of cumulative damage and analyzes its digital character. The reliability index is calculated by using advanced first order second moment reliability method and the stochastic finite element method because the structures are stochastic, the significant failure modes are identified by using the advanced branch and bound method, and the reliability of structural system is evaluated by PNET method. A numerical example is indicated that the fatigue reliability index of structural system can fulfils the demand of fatigue reliability in the design life, but the stiffness reliability index of structural system descends with the increase of the service life, and the stiffness reliability index can not fulfils the demand of the design when life over one third of the whole service life, it shows that the cumulative damage influence to structural stiffness reliability analysis can’t be ignored.

The Fatigue Reliability Evaluation & Improvement of the Single-Arm Subway Current Collector

2012 ◽  
Vol 215-216 ◽  
pp. 826-831 ◽  
Author(s):  
Yu Chen ◽  
Zhi Ming Liu ◽  
Qiang Li
Keyword(s):  
Fatigue Life ◽  
Calculation Result ◽  
Dynamic Stress ◽  
Current Collector ◽  
Reliability Evaluation ◽  
Fatigue Reliability ◽  
Railway Vehicles ◽  
Load Spectra ◽  
Reliability Method

This study developed a fatigue reliability method for evaluating and improving the key parts on railway vehicles, which was applied to real structures. The study involved a type of single-arm current collector, while its contact shoe often collapsed in operation and needs improvements. The dynamic stress data from the actual line was tested and converted to load spectra based on damage consistency rule, and then the fatigue life of the contact shoe structure was achieved. The calculation result comes to correspond to its operation life. Based on the method, an improving plan for the structure was developed under optimizing algorithms.

TTK Chitra tilting disc heart valve model TC2: An assessment of fatigue life and durability

2017 ◽  
Vol 231 (8) ◽  
pp. 758-765 ◽  
Author(s):  
NN Subhash ◽  
Adathala Rajeev ◽  
Sreedharan Sujesh ◽  
CV Muraleedharan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Heart Valve ◽  
Life Prediction ◽  
Heart Valves ◽  
Failure Modes ◽  
Fatigue Life Prediction ◽  
Element Analysis ◽  
Valve Model

Average age group of heart valve replacement in India and most of the Third World countries is below 30 years. Hence, the valve for such patients need to be designed to have a service life of 50 years or more which corresponds to 2000 million cycles of operation. The purpose of this study was to assess the structural performance of the TTK Chitra tilting disc heart valve model TC2 and thereby address its durability. The TC2 model tilting disc heart valves were assessed to evaluate the risks connected with potential structural failure modes. To be more specific, the studies covered the finite element analysis–based fatigue life prediction and accelerated durability testing of the tilting disc heart valves for nine different valve sizes. First, finite element analysis–based fatigue life prediction showed that all nine valve sizes were in the infinite life region. Second, accelerated durability test showed that all nine valve sizes remained functional for 400 million cycles under experimental conditions. The study ensures the continued function of TC2 model tilting disc heart valves over duration in excess of 50 years. The results imply that the TC2 model valve designs are structurally safe, reliable and durable.

Prediction Approach for Corrosion Fatigue Life of Aircraft Structure Based on Probabilistic Fracture Mechanics

2006 ◽  
Vol 324-325 ◽  
pp. 943-946
Author(s):  
Xiao Ming Tan ◽  
Yue Liang Chen ◽  
Ping Jin
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Corrosion Fatigue ◽  
Failure Process ◽  
Short Crack ◽  
Aircraft Structure ◽  
Probabilistic Fracture Mechanics ◽  
Fracture Failure ◽  
Reliability Method ◽  
Prediction Approach

The corrosion, corrosion fatigue and fracture failure process of aircraft structure is directly concerned with combined effect of many factors, such as load, material characteristics, corrosive environment and so on. The process is very complicated, and there is typical randomness. Based on probabilistic fracture mechanics, with consideration of the limitation of the conventional probabilistic approaches for prediction of corrosion fatigue life of aircraft structure at present, and a new reliability approach under loading spectrum was proposed, in which corrosion damage and fatigue crack damage was united as a same damage parameter. Short crack and long crack growth behavior was separately discussed, and influence of short crack aspect ratio on structure life was discussed. The Advanced First-Order Reliability Method, Importance Sampling Method and iteratively advanced Second-Order Reliability Method were used to compute the fracture failure probability. The results show that the model is feasible. By sensitivity analysis of random parameter, the important parameter was obtained, which helped to monitor the structure fatigue life.

Reliability analysis of wood I-joists

1993 ◽  
Vol 20 (4) ◽  
pp. 564-573 ◽  
Author(s):  
R. O. Foschi ◽  
F. Z. Yao
Keyword(s):  
Reliability Analysis ◽  
Carrying Capacity ◽  
Failure Modes ◽  
Limit State ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Element Analysis ◽  
Strength Limit ◽  
Reliability Method ◽  
Load Carrying

This paper presents a reliability analysis of wood I-joists for both strength and serviceability limit states. Results are obtained from a finite element analysis coupled with a first-order reliability method. For the strength limit state of load-carrying capacity, multiple failure modes are considered, each involving the interaction of several random variables. Good agreement is achieved between the test results and the theoretical prediction of variability in load-carrying capacity. Finally, a procedure is given to obtain load-sharing adjustment factors applicable to repetitive member systems such as floors and flat roofs. Key words: reliability, limit state design, wood composites, I-joist, structural analysis.

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