- Title
- A validity framework theory and fatigue damage function for an S–N plane
- Creator
- Eskandari, Hoda
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2016
- Description
- Masters Research - Master of Philosophy (MPhil)
- Description
- Fatigue life predictions associated with S–N curves have been largely based on empiricism due to the complexity involving multiple variables such as fatigue life, applied stress, number of loading cycles and stress ratio. A damage model proposed by Palmgren in1924 and popularised by Miner in 1945 may be one of the most important milestones in the history of fatigue damage research. However, its validity and the principle it adopts have been questioned, and many researchers have attempted to refine the model without much success. The ultimate objectives of the current work were to provide a validity framework theory for fatigue damage associated with the S–N curve and to derive a damage function capable of predicting fatigue life. The validity framework is designed as the fundamental basis to ensure the validity of a damage function in the development process. In the current work, a validity framework theory consisting of axioms, relative conditions for compatibility and boundary conditions is developed for fatigue damage on an S–N plane at a stress ratio of zero. The compatibility in fatigue damage was conceptualised. Manifestation points for accumulated damage were defined and conceptualised for boundary conditions by differentiating between damage accumulated before failure, and failure caused by damage. A selected equation for damage at failure as the reference damage was theoretically validated for further validation of damage on the S–N plane. Also, a damage function capable of predicting fatigue damage is proposed following the validation process. Comparisons between experimental results from two stress level sequence loading and theoretical fatigue life predictions were made and a close agreement between them was found. An evaluative review on conventional fatigue damage models is presented along with the benefits of the new compatibility concept and criteria developed here.
- Subject
- fatigue; model; review; prediction; remaining fatigue life; compatibility; S-N curve; damage; validity; theory
- Identifier
- http://hdl.handle.net/1959.13/1312020
- Identifier
- uon:22334
- Rights
- Copyright 2016 Hoda Eskandari
- Language
- eng
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