Fatigue Failure Predictions at Stress Concentrations Using Critical Distance Methods

2004 ◽  
Author(s):  
David Lanning ◽  
Theodore Nicholas ◽  
Anthony Palazotto
Keyword(s):  
Fatigue Failure ◽  
Critical Distance ◽  
Stress Concentrations ◽  
Distance Methods ◽  
Failure Predictions

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.

Effect of Longitudinal Fastener Stiffness on Fastening System Loading - Initial Findings

2021 ◽  
Author(s):  
Christian J. Khachaturian ◽  
Marcus S. Dersch ◽  
J. Riley Edwards ◽  
Matheus Trizotto
Keyword(s):  
North America ◽  
Analytical Model ◽  
Fatigue Failure ◽  
Analytical Method ◽  
Vertical Load ◽  
Stress Concentrations ◽  
Laboratory Experimentation ◽  
The Past ◽  
Track Stiffness ◽  
Fatigue Failures

Abstract Over the past 20 years, there have been at least 10 derailments due to spike fatigue failures in North America. Researchers believe that fatigue failure is caused by a combination of lateral and longitudinal spike loading. The literature indicates the vertical load and fastener friction must be considered when estimating failure locations. Though the in-track vertical, lateral, and longitudinal fastener forces have been quantified at a location that has experienced spike failures, there is a need to account for additional fasteners and track locations. Fastening systems can affect track stiffness, thus, laboratory experimentation was performed to quantify stiffness of multiple fastening systems. This data was input into an analytical model which quantified the effect of stiffness on longitudinal fastener loading. The data indicate there is significant variance in fastening system stiffness within, and between, systems. However, this variation in fastener stiffness has a reduced effect on the load transferred to the fastening system. More work is needed to validate this in the lab or field given variability within a system could lead to stress concentrations that are not fully captured using the current idealized analytical method.

Fatigue failure predictions for steels in the very high cycle region – A review and recommendations

2014 ◽  
Vol 45 ◽  
pp. 421-435 ◽  
Author(s):  
Chaminda S. Bandara ◽  
Sudath C. Siriwardane ◽  
Udaya I. Dissanayake ◽  
Ranjith Dissanayake
Keyword(s):  
Fatigue Failure ◽  
Failure Predictions ◽  
Very High

The Ability of Current Models for Fatigue Life Prediction of Shot Peened Components

2009 ◽  
Vol 417-418 ◽  
pp. 901-904 ◽  
Author(s):  
Ricardo A. Cláudio ◽  
José M. Silva ◽  
Carlos M. Branco ◽  
Jim Byrne
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fracture Mechanics ◽  
Shot Peening ◽  
Life Prediction ◽  
Compressive Residual Stress ◽  
Prediction Models ◽  
Critical Distance ◽  
Fatigue Life Prediction ◽  
Distance Methods

It is well known that shot peening has a marked benefit on fatigue life for the majority of applications. This effect is attributed mainly due to the compressive residual stress state at the component’s surface due to shot peening. The present paper evaluates the ability of several fatigue life prediction models, commonly used for general analyses, to predict the behaviour of components with compressive residual stress due to shot peening. Advanced elastic-plastic finite element analyses were carried out in order to obtain stress, strain, strain energy and fracture mechanics parameters for cracks within a compressive residual stress field. With these results several total fatigue life prediction models (including critical distance methods) and fracture mechanics based models were applied in order to predict fatigue life. Fatigue life predictions were compared with several experimental fatigue tests carried out on specimens, representative of a critical region of a compressor disc in a gas turbine aero engine. The results obtained showed that total fatigue life methods, even if combined with critical distance methods, give conservative results when shot peening is considered. Fatigue life was successfully predicted using the method proposed by Cameron and Smith, by adding initiation life to crack propagation life. This last method was also successfully applied for the prediction of non-propagating cracks that were observed during the experimental tests.

Experimental Study on Theory of Critical Distance Applied to the Prediction of Fatigue from Notches

2011 ◽  
Vol 275 ◽  
pp. 27-30
Author(s):  
Richard E. Clegg ◽  
Kai Duan ◽  
Alan J. McLeod
Keyword(s):  
Experimental Study ◽  
Fatigue Fracture ◽  
Fatigue Failure ◽  
Aluminium Alloys ◽  
Numerical Study ◽  
Critical Distance ◽  
Research Topic ◽  
Active Research

Fatigue failure of metal components containing notches, cracks and other defects has been a very active research topic for well over seven decades because of its important practical and theoretical implications. Recently, Taylor and his colleagues have re-visited this topic and proposed the Theory of Critical Distance (TCD), which summarizes the early work by Neuber, Peterson and others in a unifying theory and predicts fatigue fracture with the use of a critical distance, L0. In this paper, an experimental and numerical study of the fatigue of notched and unnotched 6061 aluminium alloys is used to verify the TCD and some of the limitations of the TCD are discussed on this basis.

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