The paper was presented at the Eleventh Meeting “New Trends in Fatigue and Fracture” (NT2F11) Polignano a Mare, Italy, 3–6 July, 2011 Zitouni Azari 1 , Caterina Casavola 2 , Carmine Pappalettere 2 , Catalin Iulian Pruncu 2 NUMERICAL SIMULATION IN COATED MATERIALS: MODEL OF CRACK PROPAGATION BI-MATERIAL NUMERI ČKA SIMULACIJA MATERIJALA SA PREVLAKOM: MODEL RASTA PRSLINE BI-MATERIJALA Originalni naučni rad / Original scientific paper UDK /UDC: 539.42:519.87 Rad primljen / Paper received: 21.01.2012. Adresa autora / Author's address: 1) Laboratoire de Mécanique, Biomécanique, Polymères, Structures (LaBPS), Ecole Nationale d’Ingénieurs de Metz, Université Paul Verlaine de Metz, France 2) Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, Italy, email: c.pruncu@poliba.it Keywords • stress intensity factors • intermetallic layer • crack propagation • bi-material Abstract From the simple device to complex assembly, protection against corrosion is the most important treatment. As well as known, this treatment could be done in different varieties in the function of available resources and depending on economic price. Most of the time, protection is made with the use of one material, that holds the highest anti-corro- sion characteristics, through a form of a thin film layer. Among various materials, zinc may be considered as one. Zinc could be applied under the thin layer during the hot dip galvanized steel process. During this procedure of steel coating, some cracks are initiated in the intermetallic layer δ and spread in the layered surface of the zinc coating. For the simulation of this process we use the finite element method (FEM). The realization of modelling is done in the bi-material steel-zinc model, using the computer software application Abaqus 6.10.1. Ključne reči • faktori intenziteta napona • intermetalni sloj • rast prsline • bi-materijal Izvod Od jednostavnog uređaja pa do kompleksnog sklopa, najvažnija obrada je zaštita od korozije. Koliko je poznato, ova obrada se može izvesti na različite načine, u funkciji postojećih resursa i u zavisnosti od ekonomskih uslova cene. U dužem vremenskom intervalu, zaštita se izvodi primenom jednog materijala, koji ima najbolje antikorozivne karakte- ristike, u obliku tankog sloja filma. Cink se smatra jednim od materijala za ovu primenu. Cink se može primeniti kao tanak sloj tokom procesa tople galvanizacije čelika uranjanjem. Tokom ovog postupka prevlačenja čelika, neke prsline se iniciraju u intermetal- nom sloju  i šire se u površini zaštitnog sloja prevlake cinka. Primenili smo metodu konačnih elemenata (FME) za simulaciju ovog procesa. Realizacija je izvedena na modelu od bi-materijala čelik-cink, primenom softverske aplikacije Abaqus 6.10.1. INTRODUCTION One important issue is the behaviour of bi-materials. Almost in every medium we can find one type of bi-materi- als. Whether it is the human body or other media located in our environment, these bi-materials may consist of coupled layers containing filler elements or without. As a model, we take into consideration from the environment, for our study, the steel-zinc bi-material. This is formed by two principal layers of steel and zinc. During the joining process called hot dip galvanised steel, the zinc undergoes several changes in the chemical composition and also in the mechanical structure represented by cracks, as we can see in Fig. 1. Generally, the behaviour of these materials could change due to the fatigue process and atmospheric attack repre- sented by rust. Influence of one discontinuity in the mate- rial during the treatment process expressed by the presence of one crack or more may be evident during life service in coated materials. zinc steel Figure 1. Structure of steel-zinc bi-material after bath at 460°C. Slika 1. Struktura bi-materijala čelik-cink, posle obrade na 460°C INTEGRITET I VEK KONSTRUKCIJA Vol. 12, br. 2 (2012), str. 125–129 STRUCTURAL INTEGRITY AND LIFE Vol. 12, No 2 (2012), pp 125–129 125