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Determination of a Shape- and Size-Independent Material Modulus for Honeycomb Structures made by Fused Deposition Modeling

Description

The purpose of the project is to study how the mechanical properties of cellular structures made by Fused Deposition Modeling (FDM) change depending on the number of unit cells and

The purpose of the project is to study how the mechanical properties of cellular structures made by Fused Deposition Modeling (FDM) change depending on the number of unit cells and the cell geometry. Specimens with three geometries of regular hexagon, square, and equilateral triangle were produced by FDM. The number of cells was varied systematically in each of the three geometries. The samples were tested for compressive strength. The specimens were laser-scanned to determine the actual dimensions, and those values were used in calculations to reduce the dimensional errors. Based on the calculations and analysis, it was concluded that for each geometry, the material modulus converged to a limiting value as the number of unit cells approached "infinity", and the convergent values of the material modulus were approximately the same (within 10% of error) for the three geometries. The convergent values for the material modulus of the hexagon, square, and triangle geometries were 273ksi, 248ksi, and 262ksi respectively. The percentages of error of the square and triangle geometries with respect to the hexagon geometry were 4.0%, and 9.2%, respectively.

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Date Created
  • 2016-12

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Sample Preparation Device for Testing of Ice-Metal Interfacial Fracture

Description

This thesis document outlines the construction of a device for preparation of cylindrical ice-aluminum specimens. These specimens are for testing in a uniaxial load cell with the goal of determining

This thesis document outlines the construction of a device for preparation of cylindrical ice-aluminum specimens. These specimens are for testing in a uniaxial load cell with the goal of determining properties of the ice-metal interface, as part of research into spray ice material properties and how such ice might be better removed from maritime vessels operating in sub-freezing temperatures. The design of the sample preparation device is outlined, justifications for design and component choices given and discussion of the design process and how problems which arose were tackled are included. Water is piped into the device through the freezers lid and sprayed by a full cone misting nozzle onto an aluminum sample rod. The sample rod is supported with Ultra High Molecular Weight Polyethylene pillars which allow for free rotation. A motor, timing belt and pulley assembly is used to rotate this metal rod at 1.25 RPM. The final device produces samples though intermittent flow in a 5 minutes on, 20 minutes off cycle. This intermittent flow is controlled through the use of a solenoid valve which is wired into the compressor. When the thermostat detects that the freezer is too warm, the compressor kicks on and the flow of water is stopped. Additional modifications to the freezer unit include the addition of a fan to cool the compressor during device operation. Recommendations are provided towards the end of the thesis, including suggestions to change the device to allow for constant flow and that deionized water be used instead of tap water due to hard water concerns.

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Date Created
  • 2016-12