3D MULTISCALE MODEL

Three-dimensional multiscale model for material degradation and fracture in polycrystalline materials

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 Obiettivo del progetto (Objective)

'The aim of this proposal is the formulation and implementation of a three-dimensional multiscale model for material degradation and fracture in polycrystalline materials. The initiation and propagation of cracks is an inherently multiscale phenomenon, in which the micro-scale material features have a direct influence on the macro-continuum response and this in turn affects the micro-state evolution. Single scale analyses are not able to address specific crack problems, due to the inability of capturing essential geometric effects related to different grain morphology, size, orientation and mechanical behavior. Multiscale methods appear to be an effective tool on investigation, as they provide and link information at different scales. The proposed model will be based on a new cohesive grain boundary integral formulation. The outcome of the project will be an high-performance computer code for 3D multiscale analysis of material degradation and damage initiation and propagation in polycrystalline materials. This could be commercialized in the future and find application in the Aerospace and Automotive industries, helping EU gain a competitive edge in this field. The stand-alone microstructure model could find application in the design of micro-devices for bioengineering applications. There are several reasons for the timing of the project: multiscale modelling is an area of recognized importance, the present work goes beyond the state of the art and it will help Europe maintain scientific competitiveness. Moreover, the outcome of the project will help EU industries in the future. Several FP7 projects contribute to this theme and the project will complement those works. Finally, the project will noticeably expand the scientific and complementary skills of the fellow, contributing to the attainment of a position of professional maturity. It will link the fellow to a strong institution assisting in the construction of the European Research Area.'

Introduzione (Teaser)

A new multi-scale model of crack initiation and propagation in polycrystalline materials promises major improvement over semi-empirical methods. This should boost the competitive position of EU aerospace and automotive industries.

Descrizione progetto (Article)

Polycrystalline materials composed of aggregates of crystals or grains of varying size and orientation exhibit complex fracture behaviours difficult to capture with single-scale models. Understanding these behaviours is important to facilitate the development of lighter and more reliable transport structures that positively impact emissions, costs and safety.

Scientists exploited a novel cohesive grain boundary integral formulation to link information at different scales with EU-funding of the MULTISCALE MODEL project. It seamlessly accounts for the way that micro-scale features affect the macro-continuum response which, in turn, affects micro-state evolution during initiation and propagation of cracks.

The grain-level model based on the cohesive-frictional grain boundary formulation accounts for the progressive intergranular degradation and failure of polycrystalline materials at the micro-scale. Computational results have been successfully compared to available data. This micro-scale model was integrated into the multi-scale model in which the macro-scale is described with a classical boundary element formulation. A material homogenisation procedure predicts the damage at the macro-scale resulting from the progressive intergranular failure of the microstructure. MULTISCALE MODEL results have been presented at several international conferences and in several publications in peer-reviewed scientific journals.

Fracture propagation predictions are still largely based on semi-empirical assumptions. More accurate modelling of the mechanisms of brittle failure in polycrystalline materials will have important impact on the EU aerospace and automotive sectors. In addition to enhancing current engineering and maintenance practices, these results also strengthen the EU position in the in the growing field of multi-scale modelling.