IMPACT ABSORBING LATTICE STRUCTURES PRODUCED BY ADDITIVE MANUFACTURING

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Roozbeh Neshani-Thesis.pdf

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2022-1-10

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Neshani, Roozbeh

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Recent technological advances rendered additive manufacturing (AM) a disruptive technology for the development and manufacturing of next generation complex parts and lightweight structures. AM of polymeric parts is widely applicable to structural parts ranging from load bearing components to impact absorbing structures. Digital Light Synthesis (DLS) is a recently developed technique that enables the reliable, fast and accurate AM of a wide range of polymeric materials. DLS is especially effective in producing lattice parts – three-dimensional open-cell structures composed of repeating unit cells. This thesis investigates elastomeric polyurethane (EPU) lattice parts produced by DLS and characterizes their mechanical properties. Initial characterization of fully dense EPU demonstrated the nonlinear hyperelastic behavior of this material combined with high elongation at fracture and excellent recovery. A combination of Ogden model and Prony series successfully described the visco-hyperelastic behavior. Next, octet-truss, BCC+CP, and cubic type lattice structures were produced and their energy absorption performances under quasi-static compression were characterized. In general, Octet-truss structures provided a more reliable and effective architecture for absorbing energy due to the balancing effects of buckling and stretching. Accurate control of the truss diameter provided means for tuning the peak stress and energy absorbance capacity of the lattice geometries for the requirements of a wide range of applications. Overall, the findings demonstrated the great potential of the EPU and the DLS technique for the design and implementation of energy-absorbing structures. Additionally, through combining the excellent capabilities of DLS 3D printing method and another type of resin, namely the rigid polyurethane RPU 70, with a novel approach of depositing NiCo (Nickel, Cobalt) metallic alloy, the feasibility of hybrid production of metal-polymer lattice structures was demonstrated. Metal plated polymer honeycomb structure exhibited orders of magnitude increase in compression strength.

Subject Keywords

Digital Light Synthesis, Electroplating, Additive Manufacturing, Lattice Structures, Energy Absorption

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https://hdl.handle.net/11511/96107

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

R. Neshani, “IMPACT ABSORBING LATTICE STRUCTURES PRODUCED BY ADDITIVE MANUFACTURING,” M.S. - Master of Science, Middle East Technical University, 2022.