Description:

The subject provides students with fundamentals of both engineering approach to failure under cyclic loading - fatigue, and finite element analysis. Fatigue and FEA lectures are separated, students has to apply these methods to solve operational life and safety of simple part at homework example.

Contents:

FATIGUE
- Fatigue phenomenon: Wohler curve, stationary load cycles, stress/strain life curves. Stress concentration: shape factor, notch sensitivity and notch factors; load, surface, treatment and size influence. Mean stress influence: Haigh's/Smith's diagrams, equivalent stress amplitude. Faigue damage cummulation. Probability of failure.

FEM
Deformation and force approach, principle of virtual displacements, principle of total potential minimum (Lagrange's principle) - all by hinged bar structure example. Generalization of the principles in continuum. Vector spaces and Ritz's method explanation using tension-compression example with goniometric and/or piecevise linear base functions. Finite element method as particular case of Ritz's method.

Seminar contents:

No excercises. To pass an assignment student has to solve homework - calculation of durability and probability of failure of simple shaped (planar or axisymmetric) notched part under tension or bending stationary cyclic load. The shape factor of notch has to be determined using both literar resources and finite element analysis.

Recommended literature:

Lecturers's slides and other resources are placed in http://moodle.fs.cvut.cz under "Automotive Engineering" -> "European Master of Automotive Engineering" -> "Design against fatigue". This site requires CTU Id and password.

Keywords:

Fatigue, durability, reliability, variational principles in mechanics, FEA

Abbreviations used:

Semester:

• W ... winter semester (usually October - February)
• S ... spring semester (usually March - June)
• W,S ... both semesters

Mode of completion of the course:

• A ... Assessment (no grade is given to this course but credits are awarded. You will receive only P (Passed) of F (Failed) and number of credits)
• GA ... Graded Assessment (a grade is awarded for this course)
• EX ... Examination (a grade is awarded for this course)
• A, EX ... Examination (the award of Assessment is a precondition for taking the Examination in the given subject, a grade is awarded for this course)

Weekly load (hours per week):

• P ... lecture
• C ... seminar
• L ... laboratory
• R ... proseminar
• S ... seminar