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Design Against Fatigue (E111069)

Departments: | ústav mechaniky, biomech.a mechatr. (12105) | ||

Abbreviation: | Approved: | 08.06.2010 | |

Valid until: | ?? | Range: | 1P+1C |

Semestr: | * | Credits: | 2 |

Completion: | Z,ZK | Language: | EN |

Annotation

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.

Teacher's

Ing. Jan Papuga Ph.D.

Letní 2022/2023

doc. Ing. Miroslav Španiel CSc.

Letní 2022/2023

Structure

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.

- 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.

Structure of tutorial

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.

Literarture

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.

Requirements

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.

Keywords

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

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