Design Against Fatigue
- Department of Mechanics, Biomechanics and Mechatronics
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.
Fundamentals of engineering mechanics of deformable bodies: understanding displacements, strain and stress components, Hook's law, strain energy, basic tension, bending and torsion theories. Fundamentals of matrix algebra and calculus.
- Syllabus of lectures:
- 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.
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.
- Syllabus of tutorials:
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.
- Study Objective:
- understanding to fatigue phenomenon
- understanding basic phenomenological fatigue approaches, including the probability of failure
- solving of simple notched parts subjected to simple cyclic loading
- understanding variational principles particularly of deformation approach
- understandig FEM as particular case of Ritz's method
- Study materials:
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.
- Further information:
- No time-table has been prepared for this course
- The course is a part of the following study plans:
- 19 162 NMAE 2012 bez odoru základ (compulsory course in the program)