Compression performances and failure modes of 3D printed pyramidal lattice truss composite structures

https://doi.org/10.1016/j.coco.2020.100615Get rights and content

Highlights

  • The failure modes of 3D printed pyramidal structures with different strut diameters were analyzed.

  • The 3D printed pyramidal structures prepared in this study have excellent energy absorption capacity.

  • Finite element method was used to simulate compression performances and failures modes of 3D printed pyramidal structures.

Abstract

Lattice structures have several advantageous properties, including light weight, high specific strength, and high specific stiffness. 3D printing technology was used to prepare pyramidal structures with different strut diameters. Here, compression tests were used to study the effect of the relative density on the structural deformation mechanism, compression performance, and energy absorption characteristics. The 3D printed pyramidal structures with different strut diameters have three post-failure modes: fracture, stable deforming, and softening. The compression performance of the structure is greater at higher relative densities. The structure absorbs energy well at appropriate relative densities. The finite element method was used to characterize the compression behaviors of the lattice structures. A comparison of structures prepared by previous studies reveals that the 3D printed pyramidal structures prepared in this study have excellent energy absorption capacity in low-density structures.

Introduction

Lattice structures have attracted increased attention for their light weight, high specific stiffness, high specific strength, strong design, and high energy absorption [[1], [2], [3]]. Liu et al. [4] prepared a hierarchical thermoplastic composite square lattice with the interlocking assembly technique and performed a compression test. The hierarchical structure had a high capacity for energy absorption and several other advantageous properties, including deformation recovery and repeated energy absorption capability. Wang et al. [5] prepared an X-type lattice structure using carbon fiber composite and studied the mechanical properties and failure modes of the X-type structure. Xiong et al. [6] used the molding hot-press technique to prepare carbon fiber composite pyramidal structures; the corresponding failure modes were studied, and theoretical models of different failure modes were proposed. Fan [7] designed and manufactured a multi-level pyramidal structure and found that the fiber-reinforced multi-level structures had higher ductility and superior weight efficiency during energy absorption.

3D printing technology, also known as additive manufacturing (AM) and rapid prototyping (RP), has the advantages of fast speed, low cost, the ability to form complex structures, and the ability to reduce material waste [8]. A major emphasis of recent work is on the use of 3D printing technology to prepare lattice structures. For example, Peng et al. [9] used short carbon fiber reinforced polyamide 6 (CF/PA6) to prepare the honeycomb structure by 3D printing technology. The experimental results showed that the honeycomb structure prepared by CF/PA6 had good energy absorption capacity and rebound behavior. Chen et al. [10] tested the impact performance of graded lattice cylindrical structures prepared by 3D printing technology and found that the relative density had a significant effect on plastic energy absorption. 3D printing technology has also been used to prepare straight column lattice structures by orthogonal experiment to study the influence of core diameter, core length, and core distance on compression performance [11]. Simon et al. [12] used thermoplastic polyurethanes to prepare a honeycomb structure and studied its energy absorption capacity. They found that 3D-printed hyperelastic honeycombs could be used as energy-absorbing structures. Ye et al. [13] used 3D printing technology to study the influence of different printing methods on the mechanical properties of the lattice structure and found that the vertically printed lattice structure had excellent ductility and that the strut is resistant to breakage. Huang [14] et al. used 3D printing technology to prepare aluminum-based pyramidal structures and found that the mechanical properties of the structures were strongly related to the inclination angle of the strut, strut length, and strut diameter.

There are a few researches on the post-failure model of structures, and the failure model of structure is of great significance to the study of structures. In this paper, the lattice structures were prepared by 3D printing technology, and the compression performance, failure modes and energy absorption characteristics of the lattice structures under different relative densities were studied. The failure model was established, and the finite element method simulation was performed on the failure mode of the lattice structure.

Section snippets

Lattice structure design

The pyramidal structure is shown in Fig. 1. The parameters t, d, l, and ω represent the strut distance, strut diameter, strut length, and strut inclination angle, respectively. The parameters of the structure are shown in Table 1, where t = 18 mm, l = 30 mm, and ω = 60°. The strut diameter of the pyramidal structure varies. According to the arrangement of diameters from small to large, the pyramidal structures are named A, B, C, D, E, F, and G.

The relative density of the pyramidal structure is

Compression performances of structures

Fig. 2 shows the typical compression stress-strain curves of the pyramidal structures. There are three post-failure modes: fracturing, stable deformation, and softening. When the strut diameter is 9 mm and 10 mm, the strut is sufficiently stout. After the stress reaches its maximum load, the strain increases, and the stress decreases sharply. As shown in Fig. S2, strut breakage is the structure failure mode. After the lattice structures pass the elastic stage and when the diameter of the strut

Comparison

The energy absorption of the pyramidal lattice structure is shown in Table 4. The energy absorption of the lattice structure first increases and then decreases as the relative density increases (Table 4). When the relative density of the structure and the strut diameter are small, the structure experiences buckling failure or bent hinges that cause the strut to soften, which makes the structure absorb little energy. When the relative density of the structure is too large and the strut diameter

Conclusions

3D printing technology was used to prepare pyramidal lattice structures, and compression experiments were conducted to test the performance of these structures. The conclusions are as follows.

  • 1.

    Strength and elastic modulus increases as the relative density increases. The 3D printed pyramidal structure has good specific strength and specific stiffness.

  • 2.

    The energy absorption performance of the 3D printed lattice structure is related to the relative density. The structure can have great energy

CRediT authorship contribution statement

Gaoyuan Ye: Conceptualization, Data curation, Writing - original draft. Hongjie Bi: Conceptualization, Writing - original draft. Zelong Li: Methodology, Investigation. Yingcheng Hu: Formal analysis, Funding acquisition.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This project was supported by the Fundamental Research Funds for the Central Universities (2572020DR13), and the National Natural Science Foundation of China (31470581).

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These authors contributed equally to this work.

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