Browsing by Author "Blomfelt, Andreas"

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    The concepts of systems engineering
    (2021-05-02) Blomfelt, Andreas; Jaakma, Kaur; Insinööritieteiden korkeakoulu; Pietola, Matti
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    The effect of nodal dispersion on the strength and ductility of the finite triangular lattice using ductile material.
    (2024-06-10) Blomfelt, Andreas; Kivelä, Eetu; Insinööritieteiden korkeakoulu; St-Pierre, Luc
    Lattice materials are engineered structures with repeating patterns, offering high stiffness, strength, and fracture toughness with low density, making them valuable in various engineering applications. This thesis investigates the behaviour of finite triangular lattices made from ductile materials under imperfections of varying degrees of nodal dispersion. This research addresses a gap in existing literature concerning the impact of nodal dispersion imperfections on ductile lattice materials, a topic with significant implications for practical applications where manufacturing imperfections are inevitable. The study aims to understand how nodal dispersion affects the ductility, ultimate tensile strength, and work of fracture of the triangular lattice. Explicit finite element analysis is used to evaluate these properties, with model parameters optimized through sensitivity analyses of specimen width, mesh size, mass scaling, and the number of repetitions. Implicit simulations are also conducted to compare the modulus behaviour with established literature. Key findings reveal that while tensile strength remains relatively insensitive to nodal dispersion, both ductility and work of fracture significantly decrease with increased dispersion. A nodal dispersion magnitude of 0,1 strut lengths results in around 40% reduction in ductility and work of fracture, whereas tensile strength is reduced by less than 5%. The study also examines how variations in lattice relative density, parent material fracture strain, and strain hardening exponent influence these properties, highlighting their complex relationship with normalized ductility and normalized tensile strength. The results emphasize the need to consider multiple material properties when predicting the behaviour of ductile lattices with imperfections. Future research should validate these findings experimentally and explore models with periodic boundary conditions for further analysis.