Design of Functionally Graded Materials Using Transient Nonlinear Simulations and Genetic Algorithm Optimization

The objective of this research is to develop a robust methodology for the design of functionally graded materials (FGMs). FGMs are advanced composite materials that are engineered to have a smooth spatial variation of material properties. This is achieved by gradually varying the relative volume fractions and microstructure of the material constituents during fabrication. FGM components typically exhibit smaller stresses and higher factors of safety than discretely bonded monolithic materials. The aim of this research project is to create a unified framework for the simultaneous optimization of structural shape, compositional profile and microstructure of metal/ceramic FGMs that are subjected to time varying thermal and mechanical loads. The proposed technique utilizes a nonlinear elastoplastic model and numerical simulations using a meshless method to accurately analyze candidate designs. A robust multi-objective genetic algorithm will be used to simultaneously optimize structure shape, fractional composition and microstructure of the material. If successful, this project will result in a powerful design tool that could assist engineers and other professionals engaged in the design process with FGMs. It will benefit society by contributing new knowledge regarding the simulation and optimization of FGMs and by reducing the failure of mechanical components. A user-friendly software package implementing the proposed method will be developed and distributed freely on the Internet through the PI\u27s web page. The educational plan will emphasize design as an important element of engineering education by incorporating computer-aided analysis, shape and material optimization to the PI\u27s machine design and composite materials courses

Collaborative Research: Multiscale Analysis of Geological Structures That Influence Crustal Seismic Anisotropy

This project is a study of crustal material anisotropy with a focus on macroscale structural geometries and how they will modify the seismic response of rock fabrics. Seismic anisotropy is the cumulative interplay between propagating seismic waves and anisotropic earth material that manifests itself through the directional dependence of seismic wave speeds. Unraveling this effect in deformed crustal terranes is complex due to several factors, such as 3D geological geometry and heterogeneity, microscale fabric, bending of seismic raypaths due to velocity gradients, field experiments that may not offer full azimuthal coverage, and the observation of anisotropy as second-order waveform or traveltime features. While seismic anisotropy can originate from upper crustal fractures or by organized fine-scale layering of isotropic material, material anisotropy is also a cause and involves at least four factors: (1) microstructural characteristics including spatial arrangement, modal abundances, and crystallographic and shape orientations of constituent minerals(2) inherent azimuthal variation of properties and approximation using symmetry classes,(3) bulk representation (effective media) of material properties at different scales, and (4) the types and internal geometries of macroscale structures. The reorientation of sample-scale material anisotropy by macroscale structures imparts its own effect. A seismic wave will produce one type of signal response due to material; it can produce a different response due to a package of rocks that are reoriented due to the geometry of a structure. The researchers will use the concept of seismic effective media to represent earth volumes through which seismic waves travel. They will employ a representation of earth volumes that allow for a tensorial representation of effective media. This allows via the wave equation an algebraic tensor manipulation to separate the structural geometry and the rocks composing the structure. A primary goal of the project is to define the contributions of structure to form effective media. Each structure has a geometrical impulse response which will modify a rock texture into an effective medium representation of the structure. A second goal of the project is to understand how the role of microscale rock fabrics contribute towards the effective media for given structures. Both combine to produce the net effective medium that a propagating wave responds to. They will conduct a quantitative and systematic study of common crustal structural geometries and how they modify rock anisotropy, and represent structures using analytical geometry surfaces and create a rigorous and integrated methodology to calculate effective media at different scales and their combined effects on seismic wave propagation. They will also examine how the tensorial form of microscale rock fabrics are sensitive to the modal compositions and statistical orientations of constituent minerals. Results of this project will be designed to aid the seismic interpretation of real anisotropic seismic data. This project brings together expertise in seismology, structural/microstructural geology and theoretical/computational mechanics to help develop a quantitative framework for the analysis of material anisotropy and resulting seismic anisotropy in deformed polymineralic rocks of the continental crust

Numerical Modeling and Experimental Investigation of Effective Elastic Properties of the 3D Printed Gyroid Infill

A numerical homogenization approach is presented for the effective elastic moduli of 3D printed cellular infills. A representative volume element of the infill geometry is discretized using either shell or solid elements and analyzed using the finite element method. The elastic moduli of the bulk cellular material are obtained through longitudinal and shear deformations of a representative volume element under periodic boundary conditions. The method is used to analyze the elastic behavior of gyroid infills for varying infill densities. The approach is validated by comparing the Young’s modulus and Poisson’s ratio with those obtained from compression experiments. Results indicate that although the gyroid infill exhibits cubic symmetry, it is nearly isotropic with a low anisotropy index. The numerical predictions are used to develop semi-empirical equations of the effective elastic moduli of gyroid infills as a function of infill density in order to inform design and topology optimization workflows

Integration of Material Characterization, Thermoforming Simulation, and As-Formed Structural Analysis for Thermoplastic Composites

An improved simulation-based thermoforming design process based on the integration of material characterization and as-formed structural analysis is proposed. The tendency of thermoplastic composites to wrinkle during forming has made simulation critical to optimized manufacturing, but the material models required are complex and time consuming to create. A suite of experimental methods has been developed for measurement of several required properties of the molten thermoplastic composite. These methods have the potential to enhance thermoplastic composites manufacturing by simplifying and expediting the process. These material properties have been verified by application to thermomechanical forming predictions using commercial simulation software. The forming predictions showed improved agreement with experimental results compared to those using representative material properties. A tool for using thermoforming simulations to inform more accurate structural models has been tested on a simple case study, and produced results that clearly differ from those of models using idealized fiber orientations and thicknesses. This provides evidence that this type of as-formed analysis may be necessary in some cases, and may be further investigated as an open source alternative to commercial analysis software

Integrated Analytical-Computational Analysis of Microstructural Influences on Seismic Anisotropy

The magnitudes, orientations and spatial distributions of elastic anisotropy in Earth\u27s crust and mantle carry valuable information about gradients in thermal, mechanical and kinematic parameters arising from mantle convection, mantle-crust coupling and tectonic plate interactions. Relating seismic signals to deformation regimes requires knowledge of the elastic signatures (bulk stiffnesses) of different microstructures that characterize specific deformation environments, but the influence of microstructural heterogeneity on bulk stiffness has not been comprehensively evaluated. The objectives of this project are to: (1) scale up a preliminary method to determine the bulk stiffness of rocks using integrated analytical (electron backscatter diffraction) and computational (asymptotic expansion homogenization) approaches that fully account for the grain-scale elastic interactions among the different minerals in the sample; (2) apply this integrated framework to investigate the effect on elastic anisotropy of several common crustal microstructures; (3) integrate time-dependent microstructure modeling with bulk stiffness calculations to investigate the effects of strain- and process-dependent microstructure evolution on elastic anisotropy in mantle rocks; and (4) disseminate open-source software for the calculation of bulk stiffnesses from electron backscatter diffraction data and creation of synthetic (computer generated) microstructures that can be used in sensitivity analyses among other applications. Because commonly used methods, such as the Voigt, Reuss and Voigt-Reuss-Hill averages, for calculating bulk rock stiffnesses do not account for elastic interactions among the constituent minerals, they exhibit marked, non-systematic differences from stiffnesses obtained using asymptotic expansion homogenization. These objectives are important because the results would substantially improve understanding of the nature of seismic anisotropy in the Earth\u27s crust, which is composed of rocks dominated by low symmetry minerals with complex structures. Traditional methods for performing these calculations do not easily incorporate these effects. This project will develop an elegant, easily-implemented alternative method for anisotropic materials. The scientific results and computational tools that result from this project will have global application across a number of solid Earth and engineering disciplines. Open-source codes developed in this project will made available through existing open-source ELLE platform. Classroom exercises developed for Earth Science and Mechanical Engineering courses that employ this software will be make available to the community, probably through the Science Education Resource Center website at Carleton College

Critically Vulnerable Coastal Areas - A Framework for Community Based Resource Management: Vembanad, Kerala 2016

The Sustainable Development Goal (SDG) 14 emphasizes Conservation and Sustainable use of the oceans, seas and marine resources for sustainable development. Further, India's National Conservation Strategy and Policy Statement on Environmental and Development, 1992 and the National Environmental Policy, 2006 recognize the importance of multi stakeholder partnership in implementation of conservation plans for sustainable development of natural resources

Breeding for Grain Quality Improvement in Rice

Oryza sativa holds a unique position among domesticated crop species as it is one of the most important staple foods globally. Without rice, the day will not be fulfilled in most of the Asian countries. Requirement of rice for consumption is anticipated from 450 million tons in 2011 to about 490 million tons in 2020 and to around 650 million tons by 2050 globally. To meet the food demands, it has been estimated that 40 per cent more rice is needed to be produced by 2050 for the ever increasing population. Increasing incidences of both biotic and abiotic stresses under changing climate are the major constraints in rice production to meet the rapidly escalating population. Crop improvement in rice will not be completed lacking of grain quality analysis. Rice grain quality embraces storage, milling, market quality, cooking and eating quality and nutritive quality of grain. Demand for high quality rice has increased globally in recent years and continues to trend upward due to the taste preferences. Since, consumer demand in Asia and all over the world are diverse due to varied demographics and culture, defining uniform attributes to grain quality becomes more challenging. The Middle Eastern consumers highly prefer long grain, well milled rice with strong aroma while European consumers prefer long grain non aromatic rices. In Asia, Chinese consumers prefer semi-aromatic rice to pure aromatic rice. Cooked kernel elongation is the most important quality traits, which differentiate the highly valued basmati rice from other rice types. Kernel elongation after cooking is an important character of fine rice and the most rice consumers prefer lengthwise elongation