Fatigue and life estimation of aeronautical stuctures

The goal of this course is to introduce students to the field of fatigue of aircraft structures. Including basic theoretical knowledge of fatigue and fracture mechanics, students are trained for proper use of modern software tools. After attending the cours, finishing all exercises and giving the final presentation, students should be able to identify the cause of fatigue cracks, type of load that brought to the development of fatigue cracks and to analyze aircraft structural life to the occurrence of fatigue cracks and to determinate residual aircraft structural life. Also, after passing the course students should be independent in estimation where fatigue crack will occur in the structure, based on a known load spectrum, by using modern software tools.

By successfully adopting the program of the course, a student acquires theoretical аnd practical knowledge to recognize type of fatigue, to determine the critical point for the fatigue crack appearance, to recognize the nature of the dynamic loads, task boundary condition for the simulation of crack growth, independent assess which numerical method gives the best problem approximation, and to determine the fatigue life of the structure before and after the fatigue crack.

1. Introduction to fatigue life assessment of aircraft structures. 2. Basic concepts in the study of fatigue characteristics. 3. Introducing the concept of damage tolerance, safe and reliable structure. 4. Introduction to elastic fracture mechanics in the assessment of fatigue crack growth and residual strength of aircraft structures. 5. Presentation in describing the static fracture and residual strength of the structure. 6. Analytical and numerical determination of crack growth.

Practical training accompanies materials presented during theoretical lectures. In the beginning, students will be familiarized with work on computer and modern software tools, followed by presentation of the examples that illustrate the theoretical lessons. Examples cover complete problems, i.e. setting the boundary conditions, correction in solving complex problems, graphical representation оf solution and its analysis. Students will solve their homework independently and present it to colleagues.

Fundamental background in FEM is recommended.

Handouts, Virtual classroom (Мооdle), Powerpoint presentations, Computers with ANSYS and Abaqus software, Recommended literature and websites.

Total assigned hours: 65

New material: 40
Elaboration and examples (recapitulation): 10

Auditory exercises: 0
Laboratory exercises: 0
Calculation tasks: 0
Seminar paper: 0
Project: 0
Consultations: 0
Discussion/workshop: 0
Research study work: 0

Review and grading of calculation tasks: 10
Review and grading of lab reports: 0
Review and grading of seminar papers: 0
Review and grading of the project: 2
Test: 0
Test: 0
Final exam: 3

Activity during lectures: 40
Test/test: 0
Laboratory practice: 0
Calculation tasks: 10
Seminar paper: 0
Project: 20
Final exam: 30
Requirement for taking the exam (required number of points): 50

Manson S., Halford G., Fatigue And Durability of Structural Materials, ASM International, 2006.; Jovičić G., Živković M., Vulović S., Proračunska mehanika loma i zamora, Mašinski fakultet Univerziteta u Kragujevcu, Kragujevac, 2011.(in Serbian)