טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentFranco Shmuel
SubjectAdaptation of the Two-Term Fatigue Model to Various
Materials and Loading Modes
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Menachem Weiss
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

It has been more than 150 years since the first revelation and definition of fatigue of metals by Wohler, and many problems are still unsolved and causing fatigue failures of structures and materials in industry. Two distinct and diverse ways of understanding and researching fatigue problems are currently used by scientists in the field. One is the classical treatment of fatigue by the use of S-N curves, strain considerations, Miner's rule for programmed loading and damage mechanics. Many safety codes in industry are based on this classical approach.  The more modern method is the use of fracture mechanics, analysis of stresses at crack tips, stress intensity factors and the Paris' law for crack propagation, this approach is valuable at prediction of existing crack propagation. An attempt to combine and integrate the two approaches, to enable a comprehensive treatment of fatigue problems in engineering was done by Weiss with the introduction of the two-term fatigue model.  The current study enhances the two-term methodology by introducing a technique how to evaluate the parameters of the model and how to adapt it to various metals. The model with the updated parameters was validated by comparison to experimental results. The adapted model was also used to review Miner's rule and to classify its validity under various modes of programmed and random loading.