Course detail

Fatigue of Aircraft Structures

FSI-OUZAcad. year: 2018/2019

The course is concerned with the following topics: Brief introduction to the field of fatigue of materials. Safe-life and damage tolerance design concepts as two elementary approaches to provide the integrity of structure during its service life. Measurement of service loads, load spectra processing. Calculation of safe-life. Definition of typical flight profiles, S-N curve selection, fatigue damage accumulation hypotheses. Determination of safe-life based on fatigue tests of components and complete structure. Airworthiness requirements for damage tolerance aircraft structures, development of inspection program based on crack growth curves. Non-destructive testing techniques for aeronautical applications.

Learning outcomes of the course unit

Practical calculation of safe life of aircraft structure considering principal loads, load spectra treatment, selection of S-N curve. Overview of other topics concerning aircraft fatigue including experiences from fatigue tests carried out at the Laboratory of Institute of Aerospace Engineering.

Prerequisites

Fundamentals of structural properties and limit states of materials. Basic knowledge of strength of materials. Overview of airframe structural design. Calculation of loading acting on airplane, stress and deformation of thin-walled airframe structures.

Co-requisites

Not applicable.

Recommended optional programme components

Not applicable.

Recommended or required reading

Růžička, M., Fidranský, J.: Pevnost a životnost letadel, skriptum ČVUT, 2000. (CS)
Schijve, J.: Fatigue of Structures and Materials, Springer Science+Business Media, B.V, 2009. (EN)
Farahmand, B.: Fatigue and Fracture Mechanics of High Risk Parts, Chapman & Hall, 1997. (EN)

Planned learning activities and teaching methods

The course is taught through lectures explaining the basic principles and theory of the discipline. Exercises are focused on practical topics presented in lectures.

Assesment methods and criteria linked to learning outcomes

Graded course-unit requirements: The main criterion of evaluation is the result of a written test focused on understanding the fundamental topics of the course. Elaborated exercises and active participation in the seminars are also required.

Language of instruction

Czech

Work placements

Not applicable.

Aims

The main goal of this course is for students to understand specific approaches to the solution of aircraft fatigue related issues with regard to the knowledge acquired in previous courses.

Specification of controlled education, way of implementation and compensation for absences

Presence in the seminars is required. Missed seminars are compensated by elaboration of individual tasks.

Classification of course in study plans

  • Programme M2I-P Master's

    branch M-LPR , 2. year of study, summer semester, 4 credits, compulsory
    branch M-STL , 2. year of study, summer semester, 4 credits, compulsory

Type of course unit

 

Lecture

26 hours, optionally

Teacher / Lecturer

Syllabus

1. Fatigue design philosophies of aircraft structures.
2. Airworthiness requirements related to fatigue issues.
3. Phases of fatigue life. Fractographic reconstitution of fatigue crack growth.
4. Safe-life approach.
5. Typical flight profiles. Measurement and processing of load spectra.
6. Gust, manoeuvre and ground loads spectra. Ground-air-ground cycle.
7. Fatigue curves of aircraft structures. Fatigue damage accumulation hypotheses. Fatigue life prediction based on nominal and local approaches (NSA, LESA, LPSA).
8. Fatigue tests and their evaluation. Constant-amplitude, program, variable-amplitude and flight-simulation fatigue tests. Fatigue testing machines.
9. Estimation of safe life by means of calculation and fatigue tests. Aircraft life monitoring systems.
10. Damage tolerance approach. Development of inspection program.
11. Overall review of NDT techniques. Requirements of JSSG-2006 and MIL-A-83444 standards.
12. Fundamentals of fracture mechanics. Residual strength analysis.
13. Crack growth under constant and variable-amplitude loading.

seminars

13 hours, compulsory

Teacher / Lecturer

Syllabus

1. – 4. Safe-life evaluation of light sport aircraft according to the FAA AC23-13A methodology.
5. – 9. Calculation of safe-life of transport aircraft.
10. - 13. Crack propagation analysis of the unstiffened panel.