DETERMINING THE ELASTIC PROPERTIES OF FLEXIBLE 3D PRINTED BEAMS WITH VARIABLE INFILL DENSITIES AND PATTERNS

Anirudha Bhattacharjee; Pancho Dachkinov; Bishakh Bhattacharya; Hiroaki Wagatsuma

Anirudha Bhattacharjee Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, INDIA
Pancho Dachkinov Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu, JAPAN
Bishakh Bhattacharya Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, INDIA
Hiroaki Wagatsuma Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu, JAPAN

Abstract

Flexible non-linear 3D printed materials are rapidly gaining popularity in various engineering applications such as soft robotics, actuators, medical devices, etc. Due to their wide applicability, there is an increased research interest in characterization of their mechanical properties and performance. Unlike the conventional manufacturing processes, 3D printing has an additive character and allows for the geometry to be controlled from inside. The internal geometry and density corresponding to a given model can be tuned to a desired stiffness. In this study we investigate the effect of the infill percentage and infill geometry on the mechanical properties of 3D printed samples from flexible material by using a desktop type FDM 3D printer. The analyzed samples have the same shape and geometry – a beam with a square cross-section but the infill percentage is varied from 10 % to a 100 % with an increment of 15 %. The effects of three different types of infill geometries– rectangular, square and honeycomb have also been analytically determined. The approach for the analytical formulation adopts the methodology for calculating the in-plane properties and stiffnesses in cellular solids. The results for the mechanical properties for the different infill densities and infill geometries have been compared for all configurations. Despite the common external geometry of all beams, there is a significant change in their stiffness with the variation of the infill patterns and densities. Finally, a non-linear FEA study for the fully solid beam was conducted and compared with the analytical results. The method, used in this study can be applied for optimization of the stiffness to weight ratio during the design process of flexible 3D printed parts undergoing larger deformations.

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