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A new uniaxial testing apparatus that has been proposed takes advantage of less costly methods such as 3D printing of tensile fixtures and image reference markers for accurate data acquisition. The purpose of this research is to find methods to improve the resolution, accuracy, and repeatability of this newly designed testing apparatus. The first phase of the research involved building a program that optimized the testing apparatus design depending on the sample being tested. It was found that the design program allowed for quick modifications on the apparatus in order to test a wide variety of samples. The second phase of research was conducted using Finite Elements to determine which sample geometry reduced the impact of misalignment error most. It found that a previously proposed design by Dr. Wonmo Kang when combined with the testing apparatus lead to a large reduction in misalignment errors.
ContributorsAyoub, Yaseen (Author) / Kang, Wonmo (Thesis director) / Kashani, Hamzeh (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2022-12
Description
This thesis investigates auxetic structures' specific energy absorption properties, characterized by their negative Poisson's Ratio (NPR). Auxetics, derived from natural materials and engineered designs, are increasingly applied in automotive, aerospace, and defense industries due to their enhanced material properties like indentation resistance and fracture toughness.
The research commenced with a thorough literature review to gather relevant methodologies and insights into auxetic geometries. This was followed by analytical experiments and simulations focused on the re-entrant auxetic pattern, known for its simplicity and effectiveness. The study tested modifications to this pattern, aiming to enhance energy absorption by adjusting parameters like base thickness and adding filets.
Simulations were performed using ANSYS 2023 R2, modeling the materials under plane stress conditions to assess their mechanical responses. Two main variants were examined: the Enhanced Stiffness pattern, which alters thickness, and the Filet Re-entrant pattern, which incorporates fillets to reduce stress concentrations. Results indicated that both modifications improved energy absorption compared to the standard re-entrant design, with Filet patterns showing superior performance due to their efficient stress distribution.
This work extends the understanding of auxetic materials, demonstrating significant potential to improve safety and functionality in engineering applications through advanced material design.
ContributorsSastriawan, Yoga (Author) / Kang, Wonmo (Thesis director) / Safari, Hamid (Committee member) / Mahmoudi, Mohammadreza (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Dean, W.P. Carey School of Business (Contributor)
Created2024-05