Design of low-density high performing lattices

Shrestha, Ashesh (2022) Design of low-density high performing lattices. [USQ Project]

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The objective of this research project is to design a new topology of lattice structure and investigate the relative density and its relationship with the fracture toughness of the lattice. This thesis has undertaken research mostly on self-similar triangular lattice of multiple geometries and multiple order of hierarchies. This thesis has further investigated a hybrid lattice structures to compare and contrast with self-similar hierarchical structures. The research project was initiated with literature reviews on different lattice topology, their individual properties, different materials used on additive manufacturing, methods and modes of testing the structure.

The research began with initial simple triangular lattice design then stepped up the design by increasing the hierarchy of the lattices with small variation on design and defects on AutoCAD software. Three samples were printed of all the topologies for consistency in result using a 3D printers and PLA material. The properties of PLA material were confirmed by conducting a tensile test on dog bone specimens of the material. All the printed lattice structures were put under four-point bending test Mode I loading condition until fracture of the structure was observed. Simultaneously, the CAD files were imported into ANSYS – finite element modelling software and simulated the standard four-point bend test. The results from two methods of analysis were compared and confirmed for a concrete result.

From the experiments and simulations, it is concluded that the relative density and fracture toughness are directly related to each other, meaning, when the relative density was increased, the fracture toughness was also seen to increase. From the experimented model, the second order single layer triangular lattice performed better in terms of stress intensity factor and relative density. It was also noted that maintaining the relative density but increasing the order of hierarchy with change in topology effected the fracture toughness.

There were some constrains while conducting this research project, mostly related to manufacturing process, such as restraint in overall dimension and minimum thickness of cell wall. Hence, the experiments were carried out within these restrictions and result and analysis are based the experiment and simulation of four-point bend test.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Current – Faculty of Health, Engineering and Sciences - School of Engineering (1 Jan 2022 -)
Supervisors: Banerjee, Sourish
Qualification: Bachelor of Engineering (Honours) (Civil)
Date Deposited: 19 Jun 2023 01:14
Last Modified: 20 Jun 2023 01:04
Uncontrolled Keywords: lattice; density; fracture toughness

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