Mechanical properties and energy–absorption capabilities of thermoplastic sheet gyroid structures

Abstract

Mechanical properties and energy-absorption capabilities of thermoplastic sheet gyroid structuresThe development of additive manufacturing and lattice structures has created opportunities for the development of lightweight impact-absorption structures that can overcome most constraints of previously used materials such as expanded polystyrene foams. However, for the successful application of such structures, the effects of their variables and performance must be established. In this study, the mechanical properties and energy absorption of thermoplastic sheet gyroid structures were investigated and compared with the performance of current materials. Consequently, the specimens were tested after changing the main variables, i.e., cell size and volume fraction, of various thermoplastic materials such as acrylonitrile butadiene styrene, polylactic acid, thermoplastic polyurethane, and polyamide 12. Finally, they were tested in a quasi-static compression test and their deformation stages were photographed. The stressstrain curves of all materials changed after adopting the sheet gyroid structure, exhibiting three distinct regions: linear elastic, long collapse plateau, and densification that made them particularly applicable for energy absorption.Volume fraction affected the layer collapse. The elastic geometrical stiffness increased for higher volume fractions and smaller cells. In addition, the peak and plateau stresses increased at higher volume fractions, and while smaller cells were not directly affected, the area under the curves were. Hence, for most materials, specific energy absorption was larger for higher volume fractions and smaller cells. The constituent material properties contributed significantly to the structural behavior, exhibiting three primary deformation mechanisms, i.e., elastomeric, elastic-plastic, and elastic-brittle, resulting in a wide spectrum of properties for each application requirement. The comparison of the optimal properties with the expanded polystyrene demonstrated the ability of sheet gyroid structures to overcome most of its challenges, exhibiting a superior specific energy absorption, ability to withstand various impacts, letting air flow in its all axes, and being recyclable. Thus, sheet gyroid structures can be considered promising alternatives.

Tunable Metamaterials for Impact Mitigation

“…Owing to their ease of design and fabrication, these structures are well‐characterized in the literature and have been shown to mimic the performance of isotropic foam materials when fabricated from metals, plastics, and elastomers. [ 36 ] In this work, gyroid structures are fabricated using the same base material and print settings as plate lattices and are printed to identical external dimensions and volume density, ensuring that any differences in impact absorption performance can be attributed to the geometry of the samples. These samples permit direct experimental comparison between novel anisotropic plate lattice designs and traditional isotropic foam‐like materials in impact conditions, which is absent from previous investigations of plate lattice behavior.…”

“…Investigation into energy absorptive materials is conducted via distinct experimental methods, depending on the strain rates of interest. Load frames are capable of prescribing quasistatic to moderately dynamic (10 −5 − 10 1 s −1 ) strain rates $$\dot{\varepsilon }$$ with high precision, and are used to study energy absorption in compression for metallic, [ 4,15,31–33 ] elastomeric, [ 34,35 ] and polymeric [ 7,36,37 ] materials. For higher (10 1 − 10 4 s −1 ) strain rates, researchers use impact tests; impact energy is prescribed by controlling the mass and impact velocity of the impacting object.…”

Mechanical performance of carbon fiber‐reinforced polymer cellular structures manufactured via fused filament fabrication

“…The gyroid structure's continuously curved morphology is also advantageous for AM as it eliminates the need for support structures. Through an adjustment of its relative density, the gyroid structure can exhibit a wide range of mechanical properties and energy‐absorption behavior, 54 enabling its tuning according to the requirements of the specific application.…”

Energy Absorption Capability of Graded Hybrid Triply Periodic Minimal Surface Structures Based on Fracture Zone Controlling

“…This makes lightweight and energy absorption design widely used in engineering vehicles, aerospace, and so on. [1] Many researches have studied the energy absorption capacity of various uniform lattice structures, [2][3][4][5][6][7][8][9][10][11][12][13][14][15] mainly including some 2D lattice structures, truss structures, and novel TPMS structures. The energy absorption capacity of lattice structures includes energy absorption and energy absorption efficiency (EAE).…”