The effect of fillets and crossbars on mechanical properties of lattice structures fabricated using additive manufacturi
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ORIGINAL ARTICLE
The effect of fillets and crossbars on mechanical properties of lattice structures fabricated using additive manufacturing Ahmad Bin Arshad 1,2 & Aamer Nazir 1,2 & Jeng-Ywan Jeng 1,2 Received: 23 June 2020 / Accepted: 1 September 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract The mechanical properties of lattice structure are affected by the properties of the parent material, the relative density, and the topology of the unit cell. In many applications, the goal is to have a lightweight and stiff structure. Increase in stiffness can be achieved by increasing relative density but this also increases the mass. The second method to enhance the mechanical properties is by tailoring the topology of the unit cell. This method has an advantage over the previous method as it results in an increase in stiffness without any increase in mass of the structure. Periodic lattice structures can be designed for multiple constraints such as optimization of stiffness and energy absorption. Presence of sharp corners and edges causes stress concentrations which lead to lower energy absorption efficiency. This can be rectified by adding fillets. In this paper, two methods are shown to increase the stiffness and the specific energy absorption efficiency of the lattice structures without increasing the mass or relative density. Improvement in mechanical properties can be achieved by addition of fillets at the edges and by placing beams parallel to the loading direction. These improvements were applied to two lattice structures: Kelvin and Octet truss. Multi-jet fusion additive manufacturing was used to fabricate the samples for performing uniaxial compression testing. The results show a marked improvement in stiffness and energy absorption efficiency in the structures which incorporate fillets and vertical beams in the unit cells. Stiffness of Kelvin was improved by 32% by adding fillets and 70% by adding crossbars. The energy absorption efficiency was increased by 50% in Kelvin by adding fillets. Furthermore, the post-yield behavior and failure mechanism were also changed due to the addition of these elements. Keywords Additive manufacturing (AM) . Lattice structure . Fillets . Design for AM . Unit cell . Energy absorption efficiency . Stiffness
1 Introduction Optimal energy absorption along with high stiffness and lightweight is a crucial requirement for many industries. Lattice structures are an excellent choice for applications where stiffness is required to be as high as it can be for a given mass [1]
* Aamer Nazir [email protected] * Jeng-Ywan Jeng [email protected] 1
Department of Mechanical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 10607, Taiwan, Republic of China
2
High Speed 3D Printing Research Center, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 106, Taiwan, Republic of China
and multiple researches have been conducted to achieve this goal [2–4]. Th
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