Mechanical Behaviour of New and Novel Types of Spinoidal Cellular Materials

Abstract

The progression of additive manufacturing has paved the way for in-depth studies of various plate- or sheet-based cellular materials. Despite their promising mechanical and physical properties, these materials often display anisotropic properties and are highly sensitive to imperfections. This study explores the mechanical behaviour of cellular materials featuring isotropic spinodal-like topologies, through numerical analysis and experimental testing. Spinodal-like, Stochastic TPMS sheet-based lattices, based on Schwarz-Diamond, Schoen−IWP, and Fischer Koch S shapes, as well as their periodic equivalents, are created. A broad range of relative densities is investigated in each instance. Finite element meshes are constructed for every model, and properties such as the Elastic Modulus, Yield Strength, Plateau Strength, and Energy absorption are determined. On the experimental front, flawed samples were created using Laser Powder Bed Fusion and Ti-64 powder to evaluate sensitivity to imperfections. Spinodal-like materials demonstrated remarkable resistance to imperfections. At lower relative densities, the mechanical behaviour of stochastic TPMS is superior to that of Periodic TPMS, primarily due to their imperfection insensitivity. Numerical simulation results indicated that, in the absence of imperfections, the optimized topology of the Periodic TPMS displays superior mechanical properties to Stochastic TPMS at all relative densities. A significant impact of the original topology is observed, with Fischer Koch S producing the best performing stochastic structures. Aspects of the design are improved, and Stochastic IWP, Stochastic Primitive, and Sheet-based Gaussian Random Field lattices are numerically tested, and show dramatic improvement over the initial design, with mechanical properties matching those of Periodic IWP lattices, while retaining isotropy and imperfection insensitivity. This work expands on the understanding of stochastic TPMS structures and facilitates further improvements in their design and potential applications in various engineering fields.

Date of Award	Aug 2023
Original language	American English
Supervisor	Rashid Abu Al Rub (Supervisor)