Primerjava pravil razvoja in akumulacije poškodbe zaradi utrujanja

Žerjal, Igor (author), Šeruga, Domen (mentor), Nagode, Marko (comentor)

V magistrskem delu smo predstavili široko uporabljeno Palmgren-Minerjevo teorijo o linearni akumulaciji poškodbe in tri manj poznane metode za računanje akumulacije poškodbe. Te alternativne metode skušajo odpraviti določene pomanjkljivosti Palmgren-Minerjeve teorije in se izkažejo za boljše v primerih obremenitvene zgodovine, ki je izrazito dvo in večnivojska. Posamezne teorije smo primerjali med seboj na rezultatih večjega števila eksperimentov, ki smo jih vzeli iz javno dostopne strokovne literature. Primerjavo teorij smo opravili tudi pri izračunu življenjske dobe krmila gorskega kolesa, na katerem smo izmerili pospeške med vožnjo in tako, ob predpostavki mase, ki nanj deluje, generirali obremenitveno zgodovino. Zaradi specifičnosti alternativnih metod in izgube informacij o sosledju obremenitvenih ciklov pri štetju teh z Rainflow metodo smo predlagali postopek, kako generirati iz realne obremenitvene zgodovine ekvivalentno obremenitveno zgodovino, ki je primerna za račun življenjske dobe z alternativnimi metodami.

• Language: Slovenian
• Keywords: obratovalna trdnost, utrujenostne poškodbe, ciklična obremenjevanja, življenjska doba, sekvenčni efekti, krmila gorskih koles
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [I. Žerjal]
• Year: 2020
• Number of pages: XXIV, 70 str.
• PID: 20.500.12556/RUL-114151
• UDC: 620.178.3:62-514.5(043.2)
• COBISS.SI-ID: 17050395
• Publication date in RUL: 19.02.2020

Secondary language

• Language: English
• Title: Comparison of rules regarding damage development and accumulation due to fatigue

Abstract

In the engineering field well established Palmgren-Miner rule regarding linear damage accumulation and three other less known theories for life prediction of elements sustaining cyclic loading were presented. Those alternative theories aim to provide a solution to certain flaws of the Palmgren-Miner rule and have proven to give better results for loading histories with two and more levels. Comparison between theories was made on experimental results from available literature and on the calculation of the fatigue life for a mountain bike handlebar. Acceleration spectrum at the handlebar due to riding was measured and with the assumption of the mass acting on the handlebar a loading history was generated. Due to the specificity of the presented alternative theories and the loss of information regarding cycle sequence when using the Rainflow algorithm for cycle counting, a method for generating from the original an equivalent and for the presented alternative theories more suitable loading history was proposed.

• Keywords: fatigue, fatigue damages, cyclic loadings, fatigue life, sequence effects, mountain bike handlebars