Browsing by Author "Marko, Carl"

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    Design of an Advanced Layered Composite for Energy Dissipation using a 3D-Lattice of Micro Compliant Mechanism
    (SAE, 2016-04) Gokhale, Vaibhav V.; Marko, Carl; Alam, Tanjimul; Chaudhari, Prathamesh; Tovar, Andres; Mechanical and Energy Engineering, School of Engineering and Technology
    This work introduces a new Advanced Layered Composite (ALC) design that redirects impact load through the action of a lattice of 3D printed micro-compliant mechanisms. The first layer directly comes in contact with the impacting body and its function is to prevent an intrusion of the impacting body and uniformly distribute the impact forces over a large area. This layer can be made from fiber woven composites imbibed in the polymer matrix or from metals. The third layer is to serve a purpose of establishing contact between the protective structure and body to be protected. It can be a cushioning material or a hard metal depending on the application. The second layer is a compliant buffer zone (CBZ) which is sandwiched between two other layers is responsible for the dampening of most of the impact energy. The compliant buffer zone, comprised by the lattice of micro-compliant mechanism, is designed using topology optimization to dynamically respond by distributing localized impact in the normal direction into a distributed load in the radial direction (perpendicular to the normal direction). The compliant buffer zone depicts a large radial deformation in the middle but not on the surface, which only moves in the normal direction. The effect is a significant reduction of the interfacial shear stress with two adjacent layered phases. A low interfacial shear stress translates into a reduced delamination. The ALC’s response to the impact is tested by using dynamic finite element analysis. The proposed ALC design is intended to be used for the design of protective devices such as helmets and crashworthy components in vehicle structures.
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    DETERMINING OPTIMAL CHARACTERISTICS OF FILAMENT FOR FUSED FILAMENT FABRICATION (FFF) 3D PRINTING TECHNOLOGY
    (Office of the Vice Chancellor for Research, 2016-04-08) Isaacs, Aaron; Rodriguez, Daniel G.; Cardona, Carolina S.; Marko, Carl; Zongying, Xu
    Filament Fused Fabrication (FFF) is a 3D printing method that uses a heated nozzle to deposit partially melted material (i.e. thermoplastic filament) under software control that form layers to create a 3D part. This study analyzes optimal characteristics of filament for FFF 3D printing. Commercial filament suppliers, 3D printer manufacturers, and end-users regard filament diameter tolerance as an important indicator of 3D print quality. Despite the important role of the diameter consistency in the FFF process, few studies have addressed acceptable tolerance levels to achieve the highest 3D printing quality. The objective of this study is to investigate the impact of filament diameter tolerance on 3D printing quality. Drive gears bite into filament and force it into the heated nozzle and produces a pressure responsible for filament flow rate. Physic’s demonstrates that varying a cross sectional area (i.e. filament diameter) under a force will affect pressure. Previous studies have shown flow rate can impact surface quality, printer performance, and the mechanical properties of 3D parts. This study hypothesizes a consequence of robust nozzle designs capable of handling diameter variance do so at the expense of 3D printing quality. A pelletbased extruder is utilized to fabricate acrylonitrile butadiene styrene (ABS) filament samples using a nozzle of 1.75 mm in diameter. Temperature and extrusion rate are controlled parameters. An optical comparator and an array of digital calipers are used to measure and select fabricated samples based on filament diameter. A Self-Replicating Rapid Prototype (RepRap) 3D Printer is used and under software control print test samples into pre-defined line widths sensitive to flow rate fluctuation. The anticipated outcome of test sample line width error against its respective filament diameter tolerance will determine the acceptable filament tolerance on 3D printing quality. This study was sponsored by the Indiana University-Purdue University Indianapolis Multidisciplinary Undergraduate Research Institute (MURI)