Search | Directories | Reference Tools
UW Home > Discover UW > Student Guide > Course Catalog 

Instructor Class Description

Time Schedule:

Patrick Safarian
A A 531
Seattle Campus

Integrity of Metallic Aircraft Structures

Examines the theory of failure for metallic structures; fatigue properties, fatigue load spectrum, fatigue crack propagation, fracture mechanics, damage tolerance, fretting and corrosion fatigue, design applications, and case studies. Prerequisite: A A 530 or equivalent or permission of instructor. Offered: W, odd years.

Class description

AA 531- Integrity of Metallic Aircraft Structures Winter 2011 Syllabus

Instructor: Dr. Patrick Safarian, PE- (206)999-7885, patsafar@uw.edu Teaching Assistant: Francesco Deleo, PhD Candidate, deleof@u.washington.edu Classroom: Loew Hall Room 202 Time: Tuesdays and Thursdays 3:30-4:50 Text: Schijve, Jaap, Fatigue of Structures and Materials, Kluwer Academic Publishers, 2009; Second Edition

Full Course Outline: 1. Introduction to Fatigue Mechanism a. Background and History b. Crack nucleation c. Crack growth d. Fatigue failure 2. Design Considerations a. Stress concentration b. Eccentricity c. Load transfer d. Hard point e. Residual stresses f. Surface treatment g. Computational tools 3. Stress Intensity Factors a. Definition, K b. Elastic crack tip stresses c. Strain energy release rate, G d. Relationship of G and K e. Computation techniques f. Applications

4. Fatigue Properties a. Fatigue limits b. S-N curves c. Fatigue diagrams d. Fatigue crack growth

5. Fatigue Strength a. Notched and unnotched specimens b. S-N curves c. Analytical prediction 6. Fracture Mechanics a. Griffith theory b. Crack growth properties c. Fracture toughness d. Analytical prediction e. Crack tip plastic zone f. Plane stress and plane strain 7. Fatigue Loads and Spectra a. Load spectra b. Variable amplitude loading c. Effects of load history 8. Fatigue Damage Accumulation a. Crack growth b. Residual strength c. Failure analysis d. Fail safety e. Damage Tolerance f. Safe life g. Inspection 9. Fretting and Corrosion Fatigue a. Fretting corrosion mechanism and effects b. Corrosion fatigue mechanism and effects c. Methods to avoid 10. Fatigue and Failure of Joints and Structure a. Fastened structures b. Bonded structures c. Welded structures d. Stiffened structures Supplemental topics throughout the course include: Analytical and numerical methods to fatigue and damage tolerance analyses An extra session on a Saturday to show FEA applications Widespread Fatigue Damage and Limit of Validity Lessons learned from accidents Case studies

Project: The project will be assigned after the midterm exam, and will be due one week before the final exam. The project should be presenting the results using all good practices of a technical report, including the problem statement, the assumptions, documentation of the approach and results. Format of the project and neatness of your presentation will effect your grade.

Biographies: Patrick Safarian is the fatigue and damage tolerance technical specialist at FAA. Since 1997 he has been involved in ensuring safety of the existing fleet as well as certification of new products in Seattle Aircraft Certification Office, such as 787 and 747-8. Prior to that he spend eleven years at the Boeing Company. During that time he contributed to development of methods and allowables for fatigue and fracture mechanics standards for stress engineers, performed analytical and numerical stress analyses of highly complex structures, including failure analyses in support of in-service problems and accident investigations. Patrick received his BSME from Northrop University in 1983, MSME from California State University, Fullerton, in 1985, and completed his PhD work Mechanical Engineering at University of California, Davis, in 1987. In June 2004 he also completed his Doctorate in Theology at Bakke Graduate School. Patrick has taught damage tolerance and advance engineering mathematics courses while at Boeing for ten years. He has been teaching post-graduate engineering courses in the fields of fatigue, fracture mechanics and finite element analysis in University of Washington and Central Washington University since 1998. Patrick is married to Shohreh, and together they have five children.

Francesco Deleo has received his Bachelor of Science in Aeronautical and Astronautical Engineering from the University of Washington in 2006. In 2007 Francesco joined the graduate program at the Aeronautics and Astronautics department at the University of Washington, where it has been in the top 10% of his class ever since. In April 2007 Francesco was awarded with the George Dragseth Endowed Fellowship for his academic excellence and research involvement. In December 2008, Francesco started his PhD under the supervision of Professor Paolo Feraboli. Now, in his last year as graduate student, Francesco has become the focal for all composite crashworthiness activities, experimental and analytical. He is now taking a leading role within the FAA-sponsored organization known as CMH-17, formerly the MIL-HDBK-17, where together with Professor Paolo Feraboli and Dr. Mostafa Rassaian of Boeing he is attempting to develop new test standards for composite materials and to generate guidelines for analysis procedures. Since 2007 Francesco has authored 6 journal publications and presented at several conferences, including the American Society of Composites (ASC), the Society for the Advancement of Material and Process Engineering (SAMPE), the American Institute of Aeronautics and Astronautics (AIAA), the Joint Advanced Materials and Structures Center of Excellence (JAMS) and the Composite Materials Handbook (CMH-17).

Student learning goals

Concepts of fatigue, fracture mechanics and damage tolerance in aerospace structures analysis, including fatigue mechanism, fatigue properties and strength, stress intensity factor, damage accumulation, widespread fatigue damage, constant and variable amplitude loading, load spectra, crack growth, residual strength and failure criterion, fretting, corrosion and inspection methods. Analytical and numerical approaches to fatigue, fracture mechanics and widespread fatigue damage as part of regulatory agency requirements.

General method of instruction

Lectures and homework assignments

Recommended preparation

Read chapters of the text book prior to the lectures will help the learning tremendously.

Class assignments and grading

Weekly homeworks that are due by next class period. Midterm exam is in two parts: 1)in class 2)take home. The final exam is take home. The course project will be assigned after the midterm exam, and will be due one week before the final exam.

Grading Criteria: Midterm 30% Final 40% Homework 15% Project 15%

Grades will be curved if necessary.

Project: The project will be assigned after the midterm exam, and will be due one week before the final exam. The project should be presenting the results using all good practices of a technical report, including the problem statement, the assumptions, documentation of the approach and results. Format of the project and neatness of your presentation will effect your grade.


The information above is intended to be helpful in choosing courses. Because the instructor may further develop his/her plans for this course, its characteristics are subject to change without notice. In most cases, the official course syllabus will be distributed on the first day of class.
Last Update by Patrick Safarian
Date: 11/23/2010