Title: Fabrication-aware structural optimisation of lattice additive-manufactured with robot-arm

Authors: Kam-Ming Mark Tam; Daniel J. Marshall; Mitchell Gu; Jasmine Kim; Yijiang Huang; Justin Lavallee; Caitlin T. Mueller

Addresses: Department of Architecture, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ' Department of Architecture, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ' Department of Architecture, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ' Segal Design Institute, McCormick School of Engineering, Northwestern University, 2133 Sheridan Road, Room 1.325, Evanston, IL 60208, USA ' Department of Architecture, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ' Department of Architecture, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA ' Department of Architecture, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA

Abstract: Architectural structures achieving high strength and stiffness with intelligent, but intricate geometry may now be materialisable through additive manufacturing (AM). However, conventional layer-based AM also produces parts with inconsistent structural strength - thereby limiting AM's end-use applications. Expanding on robotics-enabled AM techniques addressing this limitation, a novel design-fabrication framework for producing structurally optimised lattices is presented here. Lattices are geometrically morphed to maximise their structural stiffness-to-weight ratio while respecting fabrication constraints imposed by the robotic printing process, and converted into tool-paths for PLA extrusion with a custom-built end effector mounted on an industrial robot arm. The printing process leverages thermal imaging for calibration, and develops a novel joint detail to increase the reliability and load-transfer capabilities of the print. Together, these techniques and methods - validated through comparative structural load testing - show promise for architecture-scale AM that combines structurally driven geometry with complexity-agnostic materialisation in new and exciting ways.

Keywords: cellular material; lattice; additive manufacturing; FDM; fused deposition modelling; robotics; octet lattice truss; conformal lattice; 3-D truss; 3-D printed joints; bonding strength; structural load testing.

DOI: 10.1504/IJRAPIDM.2018.092908

International Journal of Rapid Manufacturing, 2018 Vol.7 No.2/3, pp.120 - 168

Received: 06 May 2017
Accepted: 05 Oct 2017

Published online: 18 Jun 2018 *

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