Razvoj algoritma za procjenu visokocikličkog zamora metodom toka kiše

undergraduate thesis

• Title (english): Development of the algorithm for the high-cycle fatigue assessment via rainflow method
• Author: Eugen Kutleša
• Mentor: Zvonimir Tomičević (mentor)
• Mentor: Damjan Čakmak (komentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2021-02-25, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Ovaj rad bavi se temom analize zamora materijala. Fokus rada je usmjeren na tzv. Rainflow metodu brojanja ciklusa (metoda „toka kiše“). Rainflow metoda jedna je od metoda kojima se pojednostavljuju složene povijesti naprezanja promjenjivih amplituda u niz jednostavnih ciklusa naprezanja konstantnih amplituda. Pojednostavljena povijest naprezanja omogućuje proračun zamora. U radu se razmatraju i uspoređuju četiri varijante Rainflow metode temeljene na različitom brojanju polu-ciklusa.
Na početku rada opisan je fenomen zamornog loma, njegov uzrok u kristalnoj rešetci materijala, Wöhlerova krivulja te S-N metoda proračuna zamora.
U sljedećem dijelu nabrojene su i opisane metode brojanja ciklusa navedene u ASTM normi E1049-85 (2011).
Nadalje, uzet je ogledni primjer povijesti naprezanja iz norme te je na njemu detaljno opisan cjelokupan proračun zamora koristeći S-N metodu proračuna.
U zadnjem dijelu rada prikazani su i diskutirani rezultati analize zamora jednog stohastičkog signala povijesti naprezanja. Analiza je provedena pomoću algoritma napisanim u alatu MATLAB R2018b.

Abstract (english)

This thesis deals with the topic of fatigue analysis. The focus of the thesis is on the so-called Rainflow cycle counting method. The Rainflow method is one of the methods that simplifies complex stress/load histories of variable amplitudes into a series of simple, constant amplitude stress cycles. Simple, constant amplitude stress/load history makes the fatigue calculation possible. This thesis discusses and compares four variants of the Rainflow counting method based on different half-cycle (residual) counting.
At the beginning of the thesis, the fatigue failure phenomenon, its cause in the crystal lattice of the material, the Wöhler curve and the S-N method of fatigue calculation are described.
The following section lists and describes the cycle counting methods listed in the ASTM standard E1049-85 (2011).
Furthermore, a stress/load history benchmark example was taken from the ASTM standard and the entire fatigue calculation was described in detail using the S-N calculation method.
In the last section, the results of the fatigue analysis of a "Gaussian" stress/load history are presented and discussed. The analysis is performed by an algorithm created in MATLAB R2018b.

• Keywords: zamorni lom; rainflow; povijest naprezanja; ciklus; algoritam; kumulirano oštećenje
• Keywords (english): fatigue failure; rainflow; stress/load history; cycle; algorithm; cumulative damage
• Language: croatian
• URN:NBN: urn:nbn:hr:235:799146
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-02-19 11:58:28