Effective Design of the Graded Strut of BCC Lattice Structure for Improving Mechanical Properties.

Long Bai,Yuanxi Sun,Junfang Zhang,Changyan Yi,Xiaohong Chen

doi:10.3390/ma12132192

Abstract

In order improve the poor mechanical properties of the body-centred cubic (BCC) lattice structure, which suffers from the stress concentration effects at the nodes of the BCC unit cell, a graded-strut design method is proposed to increase the radii corner of the BCC nodes, which can obtain a new graded-strut body-centred cubic (GBCC) unit cell. After the relative density equation and the force model of the structure are obtained, the quasi-static uniaxial compression experiments and finite element analysis (FEA) of GBCC samples and BCC samples are performed. The experimental results show that for the fabricated samples with the same relative density, the GBCC can increase the initial stiffness by at least 38.20%, increase the plastic failure strength by at least 34.12%, compared with the BCC. Coupled experimental and numerical results not only suggest that the GBCC has better mechanical and impact resistance properties than the BCC, but also indicate that as the radii corner increases, the stress concentration effect at the node and the mechanical properties will be improved, which validates the proposed design method for graded-strut unit cells and can provide guidance for the design and future research on ultra-light lattice structures in related fields.

Highlights

With the rapid development of additive manufacturing technology [1,2,3,4,5,6,7,8,9] and metal lattice structure materials [10], lightweight and high-strength multi-functional materials with periodic cellular unit cells that simulate the lattice configuration of a crystal molecule lattice have become the research trends of new materials in recent years
Ptochos et al [15] proposed the shear modulus prediction model of the irregular body-centered cubic (BCC) lattice structure when the structure is shear-loaded in the X, Y- and Z-directions
Shen et al [17], Gümrük et al [18] and Mckown et al [19] examined the differences in mechanical properties of BCC, body-centred cubic with Z-struts (BCCZ)

Summary

Introduction

With the rapid development of additive manufacturing technology [1,2,3,4,5,6,7,8,9] and metal lattice structure materials [10], lightweight and high-strength multi-functional materials with periodic cellular unit cells that simulate the lattice configuration of a crystal molecule lattice have become the research trends of new materials in recent years. The body-centered cubic (BCC) lattice structure is widely used because of its simple configuration, isotropic structure and excellent adaptability to the selective laser melting (SLM) fabrication process [11]. Ushijima et al [12], Gümrük et al [13] and Feng et al [14] established theoretical prediction models of the BCC unit cell in terms of the initial stiffness and the plastic collapse strength under various stress conditions. After establishing the theoretical prediction model for the mechanical properties of BCC, it is necessary to compare and analyze the actual mechanical performance. Shen et al [17], Gümrük et al [18] and Mckown et al [19] examined the differences in mechanical properties of BCC, body-centred cubic with (vertical) Z-struts (BCCZ)

Methods

Results

Conclusion