The present course provides a comprehensive overview of methods for fatigue analysis of ship structural details including the crack propagation methods. Both simplified and spectral approach to fatigue analysis are covered. Furthermore, corrosion prediction models and ship hull degradation models are described. During the exercises, students will learn how to perform stress concentration analysis using the software package FEMAP with NX Nastran.

Student responsibilities:

Course attendance. Oral examination.

Grading and evaluation of student work over the course of instruction and at a final exam:

Colloqium. Oral examination.

Upon successful completion of the course, students will be able to (learning outcomes):

1 . Estimate fatigue life by simplified procedures

2 . Understand spectral approach for fatigue life calculation

3 . Understand crack propagation methods and corrosion progression models for ship maintenance

4 . Create a fine mesh finite element model using FEMAP software

5 . Perform the stress concentration analysis using NX Nastran

Lectures

1. Introduction. The concept of fatigue strength. Historical overview.

2. Welded joints in shipbuilding. Types, features, preparation, quality, and inspection of welds.

3. Fatigue characteristics of materials used in shipbuilding. Examples and statistics of fatigue failures. Causes of fatigue failures.

4. Ship structural critical details (hot spots) for fatigue analysis. Fatigue strength improvement of ship structural details.

5. Fatigue strength calculation methods. Design fatigue life. Load non-linearities.

6. Overview of ship structure loads. Loads classification. Calculation of transfer functions of loads and stresses fof fatigue analysis.

7. Spectral analysis of wave loads for the fatigue analysis of ship structures

8. Simplified procedure for the calculation of wave loads. Application of Classification Societies' rules.

9. Stresses in fatigue calculation. Nominal, hot-spot, and notch stresses. Stress calculation methods.

10. Importance and definition of S-N curves. Fatigue limit. Parameters affecting the S-N curve. Types of S-N curves in shipbuilding. Mean and design S-N curves.

11. Fatigue life estimation. Palmgren-Miner rule. Equivalent deterministic stress range. Haibach effect. Gamma function. Cumulative fatigue damage.

12. Corrosion deterioration of ship's hull. Types of corrosion damages. The long-term prediction models of corrosion deterioration of ship hull. Spatial variability of corrosion damages. Practical application of corrosion prediction models.

13. Fatigue crack growth. Fracture mechanics. Stress intensity factor calculation methods. Paris-Erdogan equation.

14. Application of fatigue crack propagation methods for ship hull inspection. Crack detection.

15. Retrospection and concluding remarks.

Exercises

1. FEMAP - User Interface,geometry, materials and properties, meshing

2. FEMAP - Selection methods, other meshing methods, other property parameters, groups

3. FEMAP - other meshing commands, other display options, loads and constraints, particular elements, postprocessing

4. FEMAP - practical work (stress concentrations)

5. FEMAP - practical work (stress concentrations)

6. FEMAP - practical work (stress concentrations)

7. FEMAP - practical work (stress concentrations)

8. FEMAP - practical work (stress concentrations)

9. FEMAP - practical work (stress concentrations)

10. FEMAP - practical work (stress concentrations)

11. Practical examples of corrosion prediction using MS Excel I

12. Practical examples of corrosion prediction using MS Excel II

13. Practical examples of fatigue calculations performed using MS Excel I

14. Practical examples of fatigue calculations performed using MS Excel II

15. Practical examples of fatigue calculations performed using MS Excel III

Compulsory literature:

1. Fatigue strength of ship structures, Joško Parunov, FSB, 2000, p. 0-0

Recommended literature:

2. Fatigue Handbook, A. Almar-Naes, , 1999, p. 0-0

3. Fatigue assessment of ship structures,, Det Norske Veritas, , 2018, p. 0-0

4. BV Guidance Note NI 611 DT R00 E - Guidelines for Fatigue Assessment of Steel Ships and Offshore Units, , , 2016, p. 0-0