Three dimensional fracture analysis of FGM coatings

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2004

Öğrenci: ÖZGÜR İNAN

Danışman: SERKAN DAĞ

Özet:

The main objective of this study is to model the three dimensional surface cracking problem in Functionally Graded Material (FGM) coatings bonded to homogeneous substrates. The FGM coating is assumed to be a (ZrO2) ا (Ti-6Al-4V) layer. Homogeneous ceramic, metal ا rich, ceramic ا rich and linear variation material compositions are considered in the analyses. The surface crack is assumed to have a semi ا circular crack front profile. The surface crack problem in the FGM coating ا substrate system is examined under mechanical and transient thermal loading. Structural and thermal problems are modeled using three dimensional finite elements. Strain singularity around the crack front is simulated using collapsed 20 ا node quarter ا point brick elements. Three - dimensional displacement correlation technique is utilized to extract the stress intensity factors. The main results of the study are the stress intensity factors around the crack front for FGM coating - substrate structures subjected to uniform tension, bending, fixed ا grip tension, three point bending and transient thermal loading.