A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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Subject: search.filters.subject.Energy Absorption

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    Tailorable Energy Absorbing Cellular Materials via Sintering of Dry Powder Printed Hollow Glass Microspheres
    (2024-05-01) Wereley, Norman; Park, Jungjin; Howard, John; DeMay, Matthew; Edery, Avi; Wereley, Norman
    This article examines amorphous glass-based foams as lightweight core materials for crash-resistant structures that offer tailorable energy absorption capabilities. Hollow glass microspheres (HGMs) of different densities are layered using dry powder printing (DPP), an additive manufacturing process, and subsequently sintered to consolidate these microspheres into a cellular foam structure. The tailoring of energy absorption is achieved in these foams by layering hollow microspheres with different densities and different thickness ratios of the layers. The mechanical response to quasi-static uniaxial compression of the bilayer foams is also investigated. Bilayer samples exhibit a distinctive two-step stress-strain profile that includes first and second plateau stress, as opposed to a single constant density which does not. The strain at which the second plateau occurs can be tailored by adjusting the thickness ratio of the two layers. The resulting stress-strain profiles demonstrate tailorable energy absorption. Tailorability is found to be more significant if the density values of each layer differ greatly. For comparison, bilayer samples are fabricated using epoxy at the interface instead of the co- sintering process. Epoxy-bonded samples show a different mechanical response from the co-sintered sample with a different stress-strain profile. Designing the bilayer foams enables tailoring of the stress-strain profile, so that energy-absorption requirements can be met for a specific impact condition. The implementation of these materials for energy absorption, crashworthiness, and buoyancy applications will be discussed.
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    Experimental Study of Segmented Constrained Layer Damping in Rectangular and Sinusoidal Beams
    (2020) Ude, Chinonso Oscar; Wereley, Norman M; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In the aerospace engineering field, structures are constantly subjected to vibrations that are detrimental to the effectiveness and lifespan of the technology in use. In this work the performance of segmented constrained layer damping (SCLD) treatments for reducing vibration amplitudes is experimentally evaluated. In addition, two methods of manufacture and application are presented that employ 3D printed approaches. SCLD performance is evaluated by observing the bending response of cantilevered beams and the axial response of straight and sinuous springs. Measurements show that precise sample construction using a multi-jet modeling 3D printing approach and segment spacing based on a genetic optimization algorithm, leads to SCLD treatments that are effective for reducing vibration in cantilevered beams. Results also show that curved structures can also exploit SCLD treatments to enhance damping in axial springs, but that different algorithms for optimum segment size and spacing would be needed to create treatments that are tailored to the more complex spring structures.