Calculating the Durability and Fatigue of Mechanical Components

By the end of this course, you will be able to:

• Evaluate fatigue damage mechanisms across different materials and loading conditions
• Select and apply appropriate fatigue life prediction methods for low-cycle and high-cycle regimes
• Analyze the influence of stress concentration, environment, and loading parameters on fatigue performance
• Assess fatigue behaviour of welded joints and implement strategies to improve service life
• Apply fracture mechanics principles to estimate crack initiation and propagation under cyclic loading

Description

Mechanical components subjected to cyclic loading can fail unexpectedly if fatigue behaviour is not properly accounted for. In practice, accurately predicting fatigue life requires more than applying standard formulas—it demands a clear understanding of material response, loading conditions, stress concentrations, and environmental effects. Misjudging these factors can lead to premature failure, safety risks, and costly redesigns.

This course addresses the practical challenges of fatigue life assessment in engineering design and analysis. You will examine how intrinsic material properties and extrinsic factors such as geometry, surface condition, and operating environment influence fatigue performance. The course also explores the behaviour of welded joints, cumulative damage, and fatigue performance under elevated temperatures, including creep-fatigue interaction.

Through structured methods and applied examples, you will learn how to evaluate fatigue life using both analytical approaches and finite element results. The course introduces fracture mechanics concepts to support crack propagation assessment, including Paris law behaviour and conditions approaching critical stress intensity. By the end of the course, you will be equipped with practical tools to make informed, defensible decisions about fatigue life and structural integrity in real-world engineering applications.

Who This Course Is For

This course is designed for:

• Mechanical and structural engineers involved in design, analysis, or failure assessment
• Engineers and consultants working with fatigue-critical components or systems
• Engineers in training seeking applied understanding of fatigue and fracture behaviour
• Technical professionals responsible for assessing reliability, safety, or service life of components

Day I

Fatigue damage mechanisms

• Introduction
• Cyclic load
• Fatigue damage mechanisms

Fatigue test

• Endurance limit (for high number of cycles more than 105, 106 cycles)
• Low cycle fatigue (low number of cycles)

Material behaviours are the characteristics of;

• Steels
• Nickel alloys
• Aluminum alloys

Methods to calculate the fatigue life

• Low cycle fatigue
• Stress and strain based lifing methods
• SN diagram ( s/e, N)
• Mean stress effect
• Stress concentration factor
• Parameters affecting the fatigue life; loading condition, stress concentration, surface finish, environment ...)

Case study

• Estimating the fatigue life;
• based on hand-calculated stress (beam theories)
• using the finite element stress analysis results including; determining the stress concentration factor and the stress condition (compressive, tensile and multiaxial stress distribution)

Day II

• High cycle fatigue
• Principal fatigue parameters
• Goodman Jonson method
• Other lifing methods including the ASM code for rotating shafts

Case study

• Estimating the fatigue life using hand-calculated stress
• Estimating the life using the finite element stress analysis results

Welded joints characteristics

• Welded joints fatigue behaviours
• Methods to improve the welded joint fatigue life

Cumulative damage

• Miner rule
• Rain Flow

Fatigue at high temperature

• Environment effect
• Creep fatigue interaction

Introduction to fracture mechanics

• Basics of fracture mechanics
• Fatigue crack propagation
• Paris regime
• Close to the critical stress intensity factor
• Stress concentration zone and short crack propagation