Abstract

This work is concentrated on research of torsion properties of TPMS structures, numerically and experimentally. Currently, there are not many works that concentrate on studying torsion properties of TPMS structures. Most of them are concentrated on structures for biomedical applications and structures, printed of Ti6Al4V titanium alloy. In other areas, such as aerospace, automotive, etc. TPMS structures may also find applications. In this work, shear modulus, shear strength and resilience are tested, depending of the following conditions: cell geometries Diamond, Gyroid and Primitive, with relative densities of 30%, 50% and 70%, and unit cell sizes of 10 mm, 15 mm and 20 mm. Sample has a diameter of 20 mm and length of 40 mm. Size of all the samples is the same. For the study, full-factorial design is used, meaning that there all 27 possible conditions are tested. Simulation is done in Abaqus 2022 software. Mesh convergence study is done to define optimal mesh size. Material properties obtained, based on paper review. Test is displacement driven, meaning that torque is applied to the sample and from that, stresses are calculated. Reference points are added to represent the surfaces. One edge was fixed in all translations and rotations. Other was fixed in translations, perpendicular to the sample axis, but axial translation was allowed to prevent the appearance of additional tensile loads on the sample. Rotations in plane with the sample axis were also restricted. Twist is applied around the sample axis. Then, simulation is ran. After that, results are viewed and torque-revolution curves are obtained. To obtain stress-strain curves, minimum moment of inertia is measured on the models. After that, stress-strain curves are calculated. Regarding Von Mises stress distribution, Diamond and Gyroid had an even distribution, while Primitive had areas, where stress was concentrated. Smaller number of unit cell size (more unit cells in the sample) leads to a more even stress distribution in the sample. Regarding effect of cell geometry, Dimond and Gyroid have shown almost identical stress-strain curves, in different configurations one of the samples had slightly higher shear yield strength and shear modulus. Primitive had the highest shear modulus and shear yield strength, with unit cell size of 10 mm and 15 mm. Regarding the effect of relative density, for most samples with its increase, shear modulus and shear yield strength increased. The exception was Primitive, where shear modulus and shear yield strength decreased with the increase of relative density. Regarding the effect of unit cell size, Diamond and Gyroid samples have shown mostly identical stress-strain curves, while Primitive has shown significant difference in properties with change in unit cell size. With the decrease of unit cell size from 20 mm to 15 mm, shear modulus and shear yield strength increased, while further decreased for 10 mm unit cell size. This difference in values increased with decrease of relative density. Regarding resilience, Primitive samples had higher values on average, than Gyroid and Diamond, who had slightly differentiating properties for different configurations. Primitive sample with relative density of 30% and unit cell size of 15 mm has shown the highest resilience, significantly higher than other samples. In summary, Diamond and Gyroid have shown less differentiating properties than Primitive. Also, stresses in Primitive were not as evenly distributed, as in Gyroid and Diamond. For Primitive, increase in relative density and decrease in unit cell size caused more even stress distribution. When there are two or more interconnections between unit cells in redial direction, stress is more evenly distributed. Gyroid and Diamond have shown properties, suitable for torsion application. Primitive can also show good properties in torsion application, but only when there are two or more unit cells in radial direction.

Library of Congress Subject Headings

Torsion--Computer simulation; Additive manufacturing; Porous materials

Publication Date

7-2025

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering

Advisor

Salman Pervaiz

Campus

RIT Dubai

Plan Codes

MECE-MS

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