Lubrication is the most means for sliding interface failure prevention because it helps separate two interacting surfaces, reduce asperity contacts and thus extend the working life of the parts. Improving the tribological performance of lubricated interfaces is a challenging work, as several influence factors are involved, such as coating, plasticity,...
Global energy demand is increasingly rapidly in today’s modern world with increasing living standards all around the world. As global energy demand rises, energy efficiency has never been more crucial and that the improvement of tribological systems is critical to the progress of the global future. A large part of...
Polymer nanocomposites have attracted great interest in recent years because of their potential as tailored materials with enhanced properties. Recent experiments have shown that polymer nanocomposites are able to achieve significant improvement in dielectrical, thermal, mechanical and other physical properties compared with their parent polymer systems. More importantly, these outstanding...
Polymer nanocomposites are a class of advanced materials comprised of soft polymer matrix and nano-filler inclusions. While it has been found qualitatively that enhancements of material properties could be achieved by dispersing inorganic nano-particles into organic polymer matrix, the intrinsic governing principles of such composite has not been thoroughly studied...
Polymer nanocomposites are a designer class of materials where nanoscale particles, functional chemistry and polymer matrix combine to yield unprecedented combinations of superior physical properties. While well-defined data representation and quantitative models have been developed in material science domains such as metallic alloys, polymer nanocomposites have remained a largely untouched...
The rapid development of flexible electronics enables a huge amount of bio-integrated applications with advantages of the mechanical compliance, stretchability and comformability of the devices. My dissertation further advances this area by a series of projects, which include designing and optimizing novel compliant structures, proposing novel elastomer encapsulation process for...
Nanoelectromechanical (NEMS) systems fabricated using atomically-thin materials have low mass and high stiffness and are thus ideal candidates for force and mass sensing applications. Transition metal dichalcogenides (TMDCs) offer certain unique properties in their few-layered form – such as piezoelectricity and a direct band gap in some cases – and...
The dissertation systematically delineates the mechanically-guided deterministic assembly of three-dimensional (3D) mesostructures by compressive buckling, covering topics from mechanics concepts, design and analysis, fabrication techniques, to application opportunities. The development of approaches to form complex 3D functional mesostructures in advanced materials is a topic of broad interest, thanks to the...
Additive manufacturing (AM) processes have advanced rapidly over the last three decades to the point where they have the potential to fundamentally change the way complex parts will be designed and fabricated in the future. Additive methods leverage the ability to join metal particles or molten droplets in a layer-by-layer...
The heart of computational materials science lies in providing fundamental insights and understanding of materials behavior and properties across different scales. The significance of this task is highlighted by the Materials Genome Initiative and the emergence of computational tools and frameworks such as materials by design, microstructure sensitive design, and...
To relate the mechanical responses of hard-soft copolymer systems with their microstructures, a coarse-grained molecular dynamics (CGMD) approach is employed. With the generic bead-spring polymer model mapped from atomistic simulations, this dissertation first studies the morphology of structures with various hard-soft compositions and interactions between hard beads. Following that, this...
The presence of unwanted biofilms on surfaces is a great concern for industrial, naval, and healthcare fields, and many other settings. To better inhibit, remove, or harness the properties of biofilms, an explanation of how specific structural or chemical features of biofilm matrix components leads to enhanced adhesion and persistence...
Flowing granular mixtures with species differing in some property, such as size, shape or density of the grains, tend to segregate (de-mix) during flow. Since flowing granular materials are common in industry, and since segregation is often unwanted and costly, understanding and mitigating segregation is an important concern in industrial...
The tension-spoke bicycle wheel owes its stiffness and strength to a cooperative relationship between the rim and the spokes: the rim holds the spokes in tension to prevent them from buckling under external loads, while the spokes channel external forces to the hub and prevent the rim from becoming severely...
Using carbon fiber reinforced plastics (CFRPs) to reduce vehicle weight has received growing attentions because it can effectively curtail greenhouse gas emissions and slow down global warming. The thermoforming process is among the most promising techniques for mass production of CFRP parts because it is highly automated and has relatively...
Additive manufacturing is a promising process that has the capability to build components with complex geometries for structural and biomedical applications. Due to the rapid and localized directional solidification of molten metallic alloys, unique phase transformations occur at the melt pool that can provide for components with greater strength and...
Modeling the mechanical performance of metal produced with additive manufacturing (AM) has proven to be a challenging task. In the as-built state, these materials have been shown to exhibit strong heterogeneity and anisotropy. Even after post-processing, such as heat treatment or hot isostatic pressing and depending on the alloy, some...
Metal Additive manufacturing (AM) processes build 3D objects by heating and consolidating material in a point-by-point manner. Unlike traditional manufacturing methods, AM allows the material properties of each point in the build to vary by controlling process conditions locally. The process parameters can be considered as inputs to the AM...
Understanding structure-property relationships for polymer nanocomposites is one of the primary challenges in discovering new, light weight, multifunctional advanced materials. Polymer nanocomposites are a class of advanced materials comprised of soft polymer matrix and nano-filler inclusions. While it has been found qualitatively that enhancements of material properties could be achieved...
Hollow biopsy needles are widely adopted medical devices for the removal of biological tissue to better identify a lesion or an abnormality observed through a physical exam or a radiology scan. These procedures can provide significantly more information than most medical tests, and they are usually performed on dermis layers,...