Article
Geometrical Scaling Effects in the Mechanical Properties of
3D-Printed Body-Centered Cubic (BCC) Lattice Structures
Alia Ruzanna Aziz
1,
*, Jin Zhou
2
, David Thorne
3
and Wesley James Cantwell
3
Citation: Aziz, A.R.; Zhou, J.;
Thorne, D.; Cantwell, W.J.
Geometrical Scaling Effects in the
Mechanical Properties of 3D-Printed
Body-Centered Cubic (BCC) Lattice
Structures. Polymers 2021, 13, 3967.
https://doi.org/10.3390/
polym13223967
Academic Editors: Clemens Holzer
and Ludwig Cardon
Received: 20 September 2021
Accepted: 2 November 2021
Published: 17 November 2021
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Attribution (CC BY) license (https://
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4.0/).
1
Advanced Materials Research Centre, Technology Innovation Institute,
Abu Dhabi 9639, United Arab Emirates
2
School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China; jin.zhou@xjtu.edu.cn
3
Aerospace Research and Innovation Center (ARIC), Khalifa University of Science and Technology,
Abu Dhabi 127788, United Arab Emirates; david.thorne@ku.ac.ae (D.T.); wesley.cantwell@ku.ac.ae (W.J.C.)
* Correspondence: alia.aziz@tii.ae
Abstract:
This paper investigates size effects on the mechanical response of additively manufactured
lattice structures based on a commercially available polylactic acid (PLA) polymer. Initial attention
is focused on investigating geometrical effects in the mechanical properties of simple beams and
cubes. Following this, a number of geometrically scaled lattice structures based on the body-centered
cubic design were manufactured and tested in order to highlight size effects in their compression
properties and failure modes. A finite element analysis was also conducted in order to compare the
predicted modes of failure with those observed experimentally. Scaling effects were observed in the
compression response of the PLA cubes, with the compression strength increasing by approximately
19% over the range of scale sizes investigated. Similar size-related effects were observed in the
flexural samples, where a brittle mode of failure was observed at all scale sizes. Here, the flexural
strength increased by approximately 18% when passing from the quarter size sample to its full-
scale counterpart. Significant size effects were observed following the compression tests on the
scaled lattice structures. Here, the compression strength increased by approximately 60% over
the four sample sizes, in spite of the fact that similar failure modes were observed in all samples.
Finally, reasonably
good agreement was observed between the predicted failure modes and those
observed experimentally. However, the FE models tended to over-estimate the mechanical properties
of the lattice structures, probably as a result of the fact that the models were assumed to be
defect free
.
Keywords:
scaling effects; additive manufacturing; PLA polymer; lattice structures; compression
tests; failure modes; finite element
1. Introduction
In recent years, there has been an unprecedented increase in the use of additively man-
ufactured parts in a range of engineering applications [
1
–
5
]. Additive manufacturing offers
engineers new opportunities to produce components of great complexity that were hith-
erto impossible to manufacture using conventional techniques. Additive manufacturing
offers many other advantages, including reduced lead times, on-demand manufacturing,
increased supply chain proficiency, shorter times to market and reduced waste [
6
–
10
].
Individual build
times for complex components can be relatively long, often being mea-
sured in many hours or even days. As a result, there is a need to develop robust approaches
that can deliver rapid answers regarding the ability to manufacture specific designs for
given applications. One way to achieve this is to build smaller components and vary the
key parameters in the manufacturing process (such as geometric parameters) to identify
how they impact the subsequent printability and performance of the finished part.
Bell and Siegmund [
11
] investigated size effects in the strength of notched 3D-printed
acrylic beams. The authors observed size effects in the strength and fracture toughness of
Polymers 2021, 13, 3967. https://doi.org/10.3390/polym13223967 https://www.mdpi.com/journal/polymers
