Atul JAIN Department Department of Materials Engineering PhD defence 04 May 2015 Supervisor Prof. dr. ir. Stepan Lomov Co-supervisor Prof. dr. ir. Ignaas Verpoest Co-supervisor Prof. dr. ir. Wim Van Paepegem Funding IWT Baekaland E-mail [email protected] Hybrid Multi-Scale Modelling Of Damage And Fatigue In Short Fiber Reinforced Composites Introduction / Objective The main goal of this project is to develop, implement, and validate methodologies for the fatigue evaluation of short fiber reinforced composites (RFRC) that are based not only on material tests but on a combination of manufacturing simulation, micromechanical modeling and macroscopic fatigue behavior (Hybrid Multiscale Model). Research Methodology A four step research strategy was used for the thesis: Step 1: Choose the correct mean field homogenization scheme Step 2: Micromechanics based damage model for SFRC Step 3: Damage at the constituent level is linked to the macroscopic fatigue properties Step 4: Process integration and validations Each of the 4 steps are validated either by experimental tests and/or full FE calculations Results & Conclusions • Mori-Tanaka formulation is found to be the most appropriate mean field homogenization scheme (Fig 1) • EqBI concept for treating fiber matrix debonding was developed and validated by full FE calculations (Fig 2) • Master SN curve approach developed to predict the local SN curves ~ only 1 SN curve is needed as input Fig 1: Mori-Tanaka formulation predicts the stresses in individual inclusions correctly while PGMT fails • Framework for fatigue simulation is developed and validated for component “Pinocchio” (Fig 3) Fig 2: FE validation of the EqBI concept is performed by using contact surfaces of varying area Fig 3: Stress contour and critical areas in Pinocchio Major publication Jain, A., Lomov, S.V., Abdin, Y., Verpoest, I., Van Paepegem, W., "Pseudo-grain discretization and full Mori-Tanaka formulation for random heterogenous media: Predictive abilities for stresses in individual inclusion and matrix" Composites Science and Technology. 87(0): p. 86-93.