Research Projects

India is rapidly developing its civil, energy and defense infrastructure. India is also increasing its nuclear generation capacity, with the total capacity likely to be about 22.5 GWe by the year 2031. Meanwhile, flow and stability of Himalayan glaciers are undergoing significant changes. Therefore, to enable India’s technological advancement and to address technical challenges associated with climate change, it is important to understand and develop predictive models for the mechanical behavior of materials with complex microstructure. For example, in structural metals under large deformation, pores nucleate by decohesion or fracture of precipitate particles of different sizes. These pores grow differently due to heterogeneous plastic deformation of the surrounding materials, leading to a wide size distribution of these pores. Alternatively, materials for nuclear fuel rods, such as uranium dioxide (UO2), are usually polycrystalline materials exhibiting pores at widely different sizes, with smaller pores inside the grains and larger pores at grain boundaries. Similarly, sea ice or glaciers also have a polycrystalline microstructure but contain pores located within grains. Despite their relevance, there have been limited attempts to model porous materials with multiscale microstructures. These studies show that depending on relative volume fraction and loading conditions, small pores could increase or decrease the growth rates of large pores, and vice versa. However, they fail to include anisotropic behavior of constituent grains which are essential to understand material failure. Thus, these studies report inaccurate estimates, especially for microscopic stress and strain fields. This motivated us to propose a project to develop an analytical homogenization framework to elucidate the role of multiscale microstructures on the overall mechanical behavior as well as on the statistics stress and strain fields in multiscale composites. We will also obtain the microscopic stress and strain fields by (full-field) Fast Fourier Transform based numerical modeling for composite materials with complex microstructure. The homogenization estimates would provide us with physical insights into material response at multiple length scales. In the second stage of the project, we will build an experimental setup that integrates an uniaxial testing facility with a 2D digital image correlation software to extract local displacement and strain fields for composite materials with complex microstructures. Moreover, we will develop inverse modeling frameworks based on classical and data-driven approaches to infer spatial distribution of material properties and the corresponding stress fields from the experimentally obtained displacement fields. The project would help us uncover the micromechanics of complex materials and guide techniques that are critical for predictive modeling of the mechanical behavior of a wide range of multiscale composites.