Computational homogenisation for modelling heterogeneous multi-phase materials

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This project aims to develop a powerful and novel computational simulation tool for predicting the large-scale (macroscopic) response of complex materials. In particular this project is concerned with the simulation of materials that are diverse or non-uniform in nature (heterogeneous). In addition to the solid, these materials may also contain regions of liquid and/or gas (multi-phase).In order to understand and simulate the large scale response of such materials that are exposed to external and internal forces, heating and/or drying, it is necessary to identify and simulate the underlying physical processes that are taking place inside the material at a small scale (micro-scale) and to take account of the complex nature of the structure of the material at this small scale.Traditionally, engineers and scientists have described the large-scale behaviour of materials by simulating their observed response without reference to the underlying processes or material composition. The proposed analysis tool aims to describe the large-scale response indirectly by simulating the processes that are taking place at the small scale. However, any attempt to model every material detail of a large scale problem is unrealistic and therefore each region of the material will be represented by a realistic small-scale description. The response of this representative part to loading will then be scaled up to the large scale. In this way the large-scale response of the material is simulated by processes that are taking place at the smallscale.This project will extend existing upscaling techniques that are applicable to purely mechanical behaviour to include coupling with heat and mass (liquid and gas) transport processes. Such a technique will permit the simulation of solids subject to extreme environmental conditions, such as heating (e.g. fire), and the effect of liquid and/or gas that occupy voids in the material. Furthermore, the research will consider how these processes change as the material composition changes. New techniques for modelling material interfaces and fractures will also be adopted.The modelling framework to be developed will be applicable to a large class of heterogeneous materials (e.g. cementitious composites, biological tissues, rocks, soils, metal composites and vegetative materials) whose large-scale behaviour cannot be interpreted without consideration of the complex processes occurring at smaller scales.