Napovedovanje dobe trajanja izdelkov z upoštevanjem tehnološke zgodovine in inkrementalnim računanjem poškodbe

Zobec, Peter (author), Klemenc, Jernej (author)

Analiza vpliva zaostalih napetosti na izračun dobe trajanja je pogosto omejena le na površinsko stanje do pojava razpoke. V tej raziskavi obravnavamo celotno dobo trajanja ciklično obremenjenega izdelka. Analiziramo število ciklov do pojava razpoke in spremljamo njeno rast skozi polja zaostalih napetosti, ki niso prisotna le na površini izdelka. Za spremljanje interakcije zaostalih napetosti s ciklično obremenitvijo oz. njene relaksacije smo uporabili kombinacijo konturne metode in digitalne korelacije slik. Za modeliranje materialnega odziva je bil uporabljen kombiniran izotropično-kinematični materialni model. Razvili smo namenski algoritem, ki je sposoben preko vpeljave kohezivnega kontakta modelirati poškodbo v obliki razpoke. Algoritem dobro opisuje trend smeri rasti, na drugi strani pa nekonzervativno podaja gradient hitrosti rasti razpoke. Spoznali smo, da lahko tlačno vnesene zaostale napetosti na mestu stran od pojava razpoke negativno vplivajo na dobo trajanja izdelka.

• Language: Slovenian
• Keywords: Zaostale napetosti, Ciklična obremenitev, Rast razpoke, Poškodba, Kombiniran izotropično-kinematični materialni model, Konturna metoda
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [P. Zobec]
• Year: 2023
• Number of pages: XXVI, 110 str.
• PID: 20.500.12556/RUL-145731
• UDC: 620.172.21:539.4.012(043.3)
• COBISS.SI-ID: 152891907
• Publication date in RUL: 11.05.2023

Secondary language

• Language: Unknown
• Title: Fatigue life prediction of products by considering manufacturing history and incremental damage calculation

Abstract

Analysis of the effects of residual stresses on fatigue life is often limited to the product surface. In this study the total fatigue life of dynamically loaded products was studied. Both the number of cycles to crack initiation and the growth of the crack with subsequent cycles was analised. The contour method and digital image correlation techniques are used to validate the interaction between residual stress and fatigue loading. The combined isotropic-kinematic material model was used to model the material response. An algorithm to simulate fatigue crack growth by modelling cracks with cohesive contact was developed. The algorithm correctly predicts the fatigue crack growth trend but cannot capture the crack propagation gradient. A residual compressive stress field away from the crack initiation site has a negative effect on fatigue life.

• Keywords: Residual stress, Cyclic load, Fatigue crack growth, Damage, Combined isotropic-kinematic material model, Contour method, Digital image correlation