Browsing by Author "Rahman, Muhammad M"

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    Additive Manufacturing of Bio-inspired Sustainable Composites
    (2024-08-08) Thakur, Md Shajedul Hoque; Rahman, Muhammad M; Ajayan, Pulickel M
    Material efficiency is a key element of sustainable development. This can be achieved by recycling and reducing material waste, as well as through innovative designs that optimize material usage. Nature has many examples of complex hierarchical designs yielding lightweight efficient structural materials. Additive manufacturing enables the fabrication of material-optimized structures and material recycling at the product’s end-of-life. Thus, addressing both aspects- sustainable materials and sustainable design. We transform waste wood into ink to facilitate the first-ever 3D printing of recyclable wood structures, and we also 3D print material efficient origami designs for the first time using a brittle material. Natural wood has long been essential in construction and furniture but traditionally wood shaping has relied on subtractive manufacturing, which leads to substantial wood waste, raising critical sustainability concerns. Herein we extract lignin and cellulose from waste wood to formulate a water-based ink that facilitates the 3D printing of wood. The printed structures, after heat treatment, closely mimic natural wood’s properties, including aesthetics and mechanical characteristics. This method also allows for incorporating reinforcements, such as natural fibers. Adding natural fibers substantially improves the mechanical properties of 3D-printed wood. iii We also add fire retardants into the wood composite, which takes the structures very close to fire-safety standards, offering a sustainable pathway for the future development of fire-resistant and recyclable 3D-printed wood structures. The ancient art of origami is attractive in modern engineering for its material- efficiency. While origami-inspired metamaterials research often focuses on flexible materials, this study investigates the use of brittle materials, with the aim to change their failure mode through origami and bio-inspired soft material coatings. A ceramic based origami structure was 3D printed and coated with a biocompatible hyperelastic polymer. Mechanical tests, both experimental and numerical simulations, revealed that the origami design imparts its anisotropic behavior to the ceramic. The hyperelastic coating distributes tensile load throughout and hinders crack propagation, increasing damage tolerance and preventing catastrophic failure. This research opens the pathway to utilizing origami engineering in brittle materials. Overall, the goal is to take a step toward sustainable materials and design through additive manufacturing of bio-inspired composites.
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    Fabrication and Characterization of Advanced Epoxy-based Composites and Nanocomposites
    (2023-08-08) Khater, Ali Zein; Ajayan, Pulickel M; Rahman, Muhammad M
    We live in the age of development. The age of new technology. Of automated manufacturing and processing. Transportation is breaking new limits, passing the boundaries of the sky towards the heavens. Soon, travel across the world in minutes will become a reality with hypersonic travel. Automated and self-driving vehicles might one day be a relied means of transportation. With these advancements in technology, a new era of materials and manufacturing are necessary. Advanced materials must be developed that can reduce weight, reduce production and manufacturing time, respond intelligently or with design and intent, and reduce waste to thrust aviation, automotives, energy, technologies, and automation of technologies into this age of automation dubbed the fourth industrial revolution (IR4.0). Herein, this thesis discusses the development and testing of epoxy composites showing how additive manufacturing (AM) can be used to better process carbon nanotubes (CNTs), how the shape memory properties of epoxy can be tuned using polyrotaxane (PR), and impact tolerance of a PR epoxy. From these efforts, it has been shown that AM facilitates the processing of CNTs thus improving the processing dynamics of CNTs in epoxy in comparison to the mold cast counterpart via void reduction and CNT dispersion, wetting, and partial alignment. Likewise, this work shows that the addition of PR to a shape memory epoxy improves the strain to failure and improves shape recovery time with increased PR loading. Lastly, the effects of PR on epoxy are investigated to show how the addition of PR affects the impact resistance under repeated low velocity impacts of incrementally increasing energies. These collective works are united by the demand for advanced materials and manufacturing developments in IR4.0 where polymers provide lightweight and mechanically robust alternatives to heavy and dense metal components. Thus, this thesis will add to the body of literature and understanding necessary to continue growing the field of materials engineering and science.