A survey on fatigue life analysis approaches for metallic notched components under multi-axial loading

2018 ◽  
Vol 233 (10) ◽  
pp. 3870-3890 ◽  
Author(s):  
Peng Luo ◽  
Weixing Yao ◽  
Yingyu Wang ◽  
Piao Li
Keyword(s):  
Fatigue Failure ◽  
Axial Loading ◽  
Local Stress ◽  
Fatigue Loading ◽  
Critical Distance ◽  
Applicable Range ◽  
Fatigue Life Analysis ◽  
Nominal Stress Approach ◽  
Notched Components ◽  
Axial Fatigue

In this paper, several fatigue failure approaches of metallic notched components under multi-axial loading in recent decades are reviewed in detail. They are classified into three categories according to their different fatigue physical mechanisms and hypotheses: nominal stress approach, local stress–strain approach and the theory of critical distance. The accuracy, applicable range and computing complexity of these three different fatigue failure theories of metallic notched specimen under multi-axial fatigue loading are given. It is concluded that theory of critical distance accords with experimental results under multi-axial fatigue loading and it gives unambiguous explanation for physical mechanism of fatigue damage. However, the computing process is complex, especially under non-proportional fatigue loading, and the key parameter of theory of critical distance is difficult to calculate especially in engineering. These difficulties limit the application of theory of critical distance.

Numerical Investigation of Pressure-Cycling Induced Fatigue Failure of Wrinkled Energy Pipelines

2021 ◽  
pp. 1-38
Author(s):  
Navjot Singh ◽  
Sreekanta Das ◽  
Peter Song ◽  
Nader Yoosef-Ghodsi
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Internal Pressure ◽  
Fatigue Failure ◽  
Fatigue Loading ◽  
Element Model ◽  
Pressure Cycling ◽  
Concentration Factors ◽  
Fatigue Life Analysis ◽  
Stress Concentration Factors

Abstract Wrinkle defects can be complex pipeline deformities to assess and can present the potential to initiate a pipeline release incident as a result of fatigue failure due to pressure cycling, if not dealt with accordingly. Specifically, the stress distribution arising due to applied loads such as internal pressure can vary rapidly due to the complex shape along the wrinkle profile, which may introduce complexities in subsequent assessments such as fatigue life analysis. This paper presents a methodology using numerical simulation for evaluating stress concentration factors of wrinkle defects of varying geometries. A nonlinear finite element model is developed to evaluate stress concentration factors induced by wrinkle defects within steel pipelines subjected to internal pressure. Afterwards, data from full-scale laboratory tests for the wrinkled pipe specimens subjected to cyclic pressure fatigue loading is analyzed to evaluate stress concentration factors for comparable wrinkle profiles. Lastly, a comparison between the results of the stress concentration factors evaluated using finite element method and test data is provided, followed with a brief discussion of potential sources of discrepancies between results obtained from these methods.

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

Assessment of the Effect of Pitting Corrosion on Fatigue Crack Initiation in Hydro Turbine Shaft

2013 ◽  
Vol 633 ◽  
pp. 186-196 ◽  
Author(s):  
Radivoje Mitrovic ◽  
Dejan Momcilovic ◽  
Ivana Atanasovska
Keyword(s):  
Pitting Corrosion ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Critical Distance ◽  
Life Assessment ◽  
Stress Concentrations ◽  
Hydro Power ◽  
Turbine Shaft ◽  
Improved Design ◽  
Material Length

Energy efficiency is a key issue worldwide, and not confined solely to the realm of engineers. Past failures of mechanical power system components must be examined carefully in order to minimise future occurrences and increase energy efficiencies. Improved design procedures have been highly sought by engineers and researchers over the past few decades. The latest verified method with strong application potential within the power industry is that of the Theory of Critical Distances (TCD). TCD is not one method, but a group of methods that have a common feature; the use of a characteristic material length parameter, the critical distance L, for calculating the influence of notch-like stress raisers under static and fatigue loading. A case study from a hydro power plant turbine shaft was chosen to illustrate the development of this methodology. The paper illustrates the application of TCD to the fatigue life assessment of a turbine shaft with stress concentrations due to pitting corrosion.

Lifetime Prediction of Components Including Initiation Phase

2006 ◽  
Author(s):  
Michael Besel ◽  
Angelika Brueckner-Foit
Keyword(s):  
Input Data ◽  
Local Stress ◽  
Fatigue Loading ◽  
Computer Code ◽  
Lifetime Distribution ◽  
Element Analysis ◽  
Initiation Phase ◽  
Mechanics Model ◽  
Critical Regions ◽  
Local Stress Field

The lifetime distribution of a component subjected to fatigue loading is calculated using a micro-mechanics model for crack initiation and a fracture mechanics model for crack growth. These models are implemented in a computer code which uses the local stress field obtained in a Finite Element analysis as input data. Elemental failure probabilities are defined which allow to identify critical regions and are independent of mesh refinement. An example is given to illustrate the capabilities of the code. Special emphasis is put on the effect of the initiation phase on the lifetime distribution.

STUDY ON FATIGUE BEHAVIOR OF STRENGTHENED NON-LOAD-CARRYING CRUCIFORM WELDED JOINTS USING CARBON FIBER SHEETS

2012 ◽  
Vol 12 (01) ◽  
pp. 179-194 ◽  
Author(s):  
TAO CHEN ◽  
QIAN-QIAN YU ◽  
XIANG-LIN GU ◽  
XIAO-LING ZHAO
Keyword(s):  
Stress Concentration ◽  
Carbon Fiber ◽  
Welded Joints ◽  
Failure Modes ◽  
Fatigue Behavior ◽  
Local Stress ◽  
Fatigue Loading ◽  
Cfrp Sheets ◽  
Load Carrying ◽  
Weld Toe

This paper reports an experimental study on the use of carbon fiber-reinforced polymer (CFRP) sheets to strengthen non-load-carrying cruciform welded joints subjected to fatigue loading. Failure modes and corresponding fatigue lives were recorded during tests. Scatter of test results was observed. Thereafter, a series of numerical analyses were performed to study the effects of weld toe radius, the number of CFRP layers and Young's modulus of reinforced materials on local stress concentration at a weld toe. It was found that fatigue life of such welded connections can be enhanced because of the reduction of stress concentration caused by CFRP strengthening. Parametric study indicates that the weld toe radius and the amount of CFRP are the key parameters influencing the stress concentration factors and stress ranges of the joint. Enhancement of modulus for adhesive and CFRP sheets can also be beneficial to the fatigue performance to some extent.

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