Vibration fatigue at half-sine impulse excitation in the time and frequency domains

Ogrinec, Primož (author), Slavič, Janko (author), Česnik, Martin (author), Boltežar, Miha (author)

Three types of loads are typical in vibration fatigue: random, harmonic and impact. In an application, any combination of these loads is possible. In vibration fatigue the random loads can be investigated by using the frequency-response function of the structure. While the theoretical relationship between the frequency-response function and the impact-response function is clear (they form the Fourier pair), the time/frequency relationship of vibration-fatigue damage has not yet been investigated in detail. The focus of this research is a theoretical study of the time- and frequency-domain damage of a single-degree-of-freedom dynamic system under well-separated half-sine impulse excitation. The introduced theoretical relationship between the time- and frequency-domain (Narrow-band and Tovo-Benasciutti method) damage showed that the significantly different results are related to the underlying dynamic properties (e.g., natural frequency and damping) of a flexible system. Based on the introduced relationship, the frequency-domain damage estimation is corrected for a reliable damage estimation. In addition, an experimental test case is presented. The introduced theoretical relationship opens up new possibilities to investigate the impact excitation in the frequency domain and provides the necessary theoretical background for applications when the impacts are not well separated and start to overlap, resulting in the broadband excitation observed in clearance contacts.

• Language: English
• Keywords: vibration fatigue, random loads, spectral methods, fatigue life, stationary loading, non-stationary loading, non-Gaussian loading
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Submitted Version
• Year: 2019
• Number of pages: Str. 308-317
• Numbering: Vol. 123
• PID: 20.500.12556/RUL-107106
• UDC: 534.12:539.43(045)
• ISSN on article: 0142-1123
• DOI: 10.1016/j.ijfatigue.2019.02.031
• COBISS.SI-ID: 16539419
• Publication date in RUL: 28.03.2019

Record is a part of a journal

• Title: International journal of fatigue
• Shortened title: Int. j. fatigue
• Publisher: Elsevier
• ISSN: 0142-1123
• COBISS.SI-ID: 25643520

Secondary language

• Language: Slovenian
• Title: Vibracijska poškodovanost v časovni in frekvenčni domeni za primer pol-sinusnih impulznih obremenitev

Abstract

V vibracijskem utrujanju se srečujemo s tremi tipi obremenitev: naključnimi, harmonskimi in impulznimi. V praksi pa so možne kombinacije teh obremenitev. Naključne obremenitve obravnavamo v frekvenčni domeni, z upoštevanjem strukturne dinamike obravnavane strukture. Medtem ko so teoretične relacije med frekvenčnimi prenosnimi funkcijami in impulzno- prenosnimi funkcijami dobro znane, razmerje med napovedjo poškodbe v časovni in frekvenčni domeni še ni bilo podrobno raziskano. V tej raziskavi je predstavljena teoretična študija napovedi poškodbe tako v časovni, kot tudi v frekvenčni domeni, za sistem z eno prostostno stopnjo, ki je obremenjen z polsinusnimi impulzi. Iz prikazanih rezultatov razmerij med časovno (padavinska) in frekvenčnima števnima metodama(ozko-spektralna, Tovo-Bennasciutti) je razvidno, da so napovedi dobe trajanja z različnimi metodami neskladne. Z predstavljenim analitičnim razmerjem je mogoče ustrezno korigirati obravnavani frekvenčni metodi. V delu je predstavljeno tudi eksperimentalno delo, ki potrjuje teoretične zaključke. Opisan analitični postopek odpira nove možnosti raziskave impulznih obremenitev v frekvenčni domeni in predstavlja potrebno teoretično ozadje za obremenitvene primere kjer impulzi niso dobro ločeni in se prekrivajo, kar rezultira v široko-spektralnem vzbujanju.

• Keywords: vibracijsko utrujanje, naključne obremenitve, spektralne števne metode, napoved dobe trajanja, stacionarne obremenitve, nestacionarne obremenitve, ne-Gaussovo vzbujanje

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0263
• Name: Mehanika v tehniki