Crack initiation criteria for singular stress concentrations, Part IV: Applications to fracture of coated structures

0322243 - ÚFM 2009 RIV CZ eng J - Journal Article
Knésl, Zdeněk - Náhlík, Luboš - Bareš, Pavel
Crack initiation criteria for singular stress concentrations, Part IV: Applications to fracture of coated structures.
[Kritéria iniciace trhlin ze singulárních koncentrátorů napětí. Část IV: Aplikace na povlakované konstrukce.]
Engineering Mechanics. Roč. 15, č. 4 (2008), s. 263-270. ISSN 1802-1484
R&D Projects: GA ČR GA106/07/1284; GA AV ČR(CZ) KJB200410803
Institutional research plan: CEZ:AV0Z20410507
Keywords : Fracture mechanics * bi-material body * thin layers * fracture of coated structures
Subject RIV: JL - Materials Fatigue, Friction Mechanics

The influence of through crack in the protective surface layer on damage of coated structure is investigated. The coated structure is modeled as a particular case of a bi-material body consisting of thin surface layer on the substrate. Specific attention is devoted to the case of a through coating crack with its tip at the interface between coating and the substrate. To estimate how the coating crack with its tip at the interface influences the substrate failure the general approach described in [1,2,3] (Part I,II III of this contribution) is applied. An approximate approach based on calculations of crack mouth opening displacement for thin protective layers is suggested and developed. It is concluded that in the case of a stiffer coating on a more compliant substrate, the through coating cracks represent dangerous stress concentrators and, as a consequence of elastic mismatch of both materials, the critical applied stress for substrate failure decreases.

Práce se zabývá šířením trhlin v ochranných povlacích a navazuje na 3 předešlé díly publikované v Engineering mechanics. V práci je upozorněno na nízkou prahovou hodnotu pro šíření trhliny přes rozhraní povlak/substrát v případě tvrdého povlaku na poddajném substrátu. Podcenění tohoto efektu by mohlo vést k nekonzervativním odhadům materiálových systémů s povrchovými vrstvami.
Permanent Link: http://hdl.handle.net/11104/0170559