Investigations on the Mechanical Response of Gradient Lattice Structures Manufactured via SLM

The main aim of the paper is to evaluate the mechanical behavior or lattice specimens subjected to quasi-static and dynamic compression tests. Both regular and three different variants of SS 316L lattice structures with gradually changed topologies (discrete, increase and decrease) have been successfully designed and additively manufactured with the use of the selective laser melting technique. The fabricated structures were subjected to geometrical quality control, microstructure analysis, phase characterization and compression tests under quasi-static and dynamic loading conditions. The mismatch between dimensions in the designed and produced lattices was noticed. It generally results from the adopted technique of the manufacturing process. The microstructure and phase composition were in good agreement with typical ones after the additive manufacturing of stainless steel. Moreover, the relationship between the structure relative density and its energy absorption capacity has been defined. The value of the maximum deformation energy depends on the adopted gradient topology and reaches the highest value for a gradually decreased topology, which also indicates the highest relative density. However, the highest rate of densification was observed for a gradually increasing topology. In addition, the results show that the gradient topology of the lattice structure affects the global deformation under the loading. Both, static and dynamic loading resulted in both barrel- and waisted-shaped deformation for lattices with an increasing and a decreasing gradient, respectively. Lattice specimens with a gradually changed topology indicate specific mechanical properties, which make them attractive in terms of energy absorption applications.

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Energy Absorption of Thermoplastic Polyurethane Lattice Structures via 3D Printing: Modeling and Prediction

International Journal of Applied Mechanics ◽

10.1142/s1758825116400068 ◽

2016 ◽

Vol 08 (07) ◽

pp. 1640006 ◽

Cited By ~ 20

Author(s):

Fei Shen ◽

Shangqin Yuan ◽

Yanchunni Guo ◽

Bo Zhao ◽

Jiaming Bai ◽

...

Keyword(s):

3D Printing ◽

Energy Absorption ◽

Mechanical Response ◽

Thermoplastic Polyurethane ◽

Selective Laser Sintering ◽

Absorption Capacity ◽

Lattice Structures ◽

Energy Absorption Capacity ◽

Cyclic Compression ◽

Manufacturing Testing

This work investigates the energy absorption capacity of polymeric lattice structures through a systemic manufacturing, testing and modeling approaches. The lattice structures are designed to possess periodic cubic geometry with optimized spherical shells located at the cubic corners, and thermoplastic polyurethane (TPU) powders are used to fabricate such structures via selective laser sintering, a type of powder-based 3D printing technology. A hyperelastic model that considers the mullins effect and describes the cyclic compression stress–strain behavior of TPU is developed to simulate the mechanical response of its 3D-printed lattice structures under cyclic compression loading. After the validation of the model for printed structure, it is used to predict the energy absorption capacity of various designed structures.

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A Comparison of Miniature Lattice Structures Produced by Material Extrusion and Vat Photopolymerization Additive Manufacturing

Polymers ◽

10.3390/polym13132163 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2163

Author(s):

Rafael Guerra Silva ◽

María Josefina Torres ◽

Jorge Zahr Viñuela

Keyword(s):

Additive Manufacturing ◽

Energy Absorption ◽

Lattice Structure ◽

Solid Material ◽

Unit Cell ◽

Lattice Structures ◽

Compression Tests ◽

Material Extrusion ◽

Lower Accuracy ◽

Manufacturing Methods

In this paper, we study the capabilities of two additive manufacturing technologies for the production of lattice structures, namely material extrusion and vat photopolymerization additive manufacturing. A set of polymer lattice structures with diverse unit cell types were built using these additive manufacturing methods and tested under compression. Lattice structures built using material extrusion had lower accuracy and a lower relative density caused by the air gaps between layers, but had higher elastic moduli and larger energy absorption capacities, as a consequence of both the thicker struts and the relatively larger strength of the feedstock material. Additionally, the deformation process in lattices was analyzed using sequential photographs taken during the compression tests, evidencing larger differences according to the manufacturing process and unit-cell type. Both additive manufacturing methods produced miniature lattice structures with similar mechanical properties, but vat polymerization should be the preferred option when high geometrical accuracy is required. Nevertheless, as the solid material determines the compressive response of the lattice structure, the broader availability of feedstock materials gives an advantage to material extrusion in applications requiring stiffer structures or with higher energy absorption capabilities.

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Compressive Properties of Functionally Graded Bionic Bamboo Lattice Structures Fabricated by FDM

Materials ◽

10.3390/ma14164410 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4410

Author(s):

Zhou Wen ◽

Ming Li

Keyword(s):

Mechanical Properties ◽

Energy Absorption ◽

Honeycomb Structure ◽

Absorption Capacity ◽

Functionally Graded ◽

Honeycomb Lattice ◽

Lattice Structures ◽

Compression Tests ◽

Uniform Lattice ◽

Static Compression

Bionic design is considered a promising approach to improve the performance of lattice structures. In this work, bamboo-inspired cubic and honeycomb lattice structures with graded strut diameters were designed and manufactured by 3D printing. Uniform lattice structures were also designed and fabricated for comparison. Quasi-static compression tests were conducted on lattice structures, and the effects of the unit cell and structure on the mechanical properties, energy absorption and deformation mode were investigated. Results indicated that the new bionic bamboo structure showed similar mechanical properties and energy absorption capacity to the honeycomb structure but performed better than the cubic structure. Compared with the uniform lattice structures, the functionally graded lattice structures showed better performance in terms of initial peak strength, compressive modulus and energy absorption.

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Mechanical response of TiAl6V4 lattice structures manufactured by selective laser melting in quasistatic and dynamic compression tests

Journal of Laser Applications ◽

10.2351/1.4898835 ◽

2015 ◽

Vol 27 (S1) ◽

pp. S17006 ◽

Cited By ~ 35

Author(s):

S. Merkt ◽

C. Hinke ◽

J. Bültmann ◽

M. Brandt ◽

Y. M. Xie

Keyword(s):

Selective Laser Melting ◽

Mechanical Response ◽

Dynamic Compression ◽

Lattice Structures ◽

Compression Tests ◽

Laser Melting

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Mechanical Characteristics of Superimposed 316L Lattice Structures under Static and Dynamic Loading

Advanced Engineering Materials ◽

10.1002/adem.202001536 ◽

2021 ◽

pp. 2001536

Author(s):

Chao Chang ◽

Wei Wu ◽

Hui Zhang ◽

Jianjun Chen ◽

Yongze Xu ◽

...

Keyword(s):

Dynamic Loading ◽

Mechanical Characteristics ◽

Lattice Structures ◽

Static And Dynamic Loading

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Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00251-1 ◽

2021 ◽

Vol 21 (3) ◽

Author(s):

S. Talebi ◽

R. Hedayati ◽

M. Sadighi

Keyword(s):

Surface Area ◽

Dynamic Behavior ◽

Energy Absorption ◽

Peak Stress ◽

Absorption Capacity ◽

Unit Cell ◽

Lattice Structures ◽

Energy Absorption Capacity ◽

Closed Cell ◽

Unit Cells

AbstractClosed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

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Mechanical Response of Porous Copper Manufactured by Lost Carbonate Sintering Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.1863 ◽

2007 ◽

Vol 539-543 ◽

pp. 1863-1867 ◽

Cited By ~ 6

Author(s):

X.F. Tao ◽

Li Ping Zhang ◽

Y.Y. Zhao

Keyword(s):

Particle Size ◽

Flexural Strength ◽

Relative Density ◽

Mechanical Response ◽

Compaction Pressure ◽

Absorption Capacity ◽

Energy Absorption Capacity ◽

Three Point Bending ◽

Porous Copper ◽

The Impact

This paper investigated the mechanical response of porous copper manufactured by LCS under three-point bending and Charpy impact conditions. The effects of the compaction pressure and K2CO3 particle size used in producing the porous copper samples and the relative density of the samples were studied. The apparent modulus, flexural strength and energy absorption capacity in three-point bending tests increased exponentially with increasing relative density. The impact strength was not markedly sensitive to relative density and had values within 7 – 9 kJ/m2 for the relative densities in the range 0.17 – 0.31. The amount of energy absorbed by a porous copper sample in the impact test was much higher than that absorbed in the three-point bending test, impling that loading strain rate had a significant effect on the deformation mechanisms. Increasing compaction pressure and increasing K2CO3 particle size resulted in significant increases in the flexural strength and the bending energy absorption capacity, both owing to the reduced sintering defects.

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An experimental investigation on mechanical performances of 3D printed lightweight ABS pipes with different cellular wall thickness

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.15.2.2021.16.0641 ◽

2021 ◽

Vol 15 (2) ◽

pp. 8169-8177

Author(s):

Berkay Ergene ◽

İsmet ŞEKEROĞLU ◽

Çağın Bolat ◽

Bekir Yalçın

Keyword(s):

Compressive Strength ◽

Energy Absorption ◽

Wall Thickness ◽

Lattice Structure ◽

Honeycomb Structure ◽

Cellular Structures ◽

Compression Tests ◽

Absorbed Energy ◽

Great Opportunity ◽

3D Printed

In recent years, cellular structures have attracted great deal of attention of many researchers due to their unique properties like exhibiting high strength at low density and great energy absorption. Also, the applications of cellular structures (or lattice structures) such as wing airfoil, tire, fiber and implant, are mainly used in aerospace, automotive, textile and biomedical industries respectively. In this investigation, the idea of using cellular structures in pipes made of acrylonitrile butadiene styrene (ABS) material was focused on and four different pipe types were designed as honeycomb structure model, straight rib pattern model, hybrid version of the first two models and fully solid model. Subsequently, these models were 3D printed by using FDM method and these lightweight pipes were subjected to compression tests in order to obtain stress-strain curves of these structures. Mechanical properties of lightweight pipes like elasticity modulus, specific modulus, compressive strength, specific compressive strength, absorbed energy and specific absorbed energy were calculated and compared to each other. Moreover, deformation modes were recorded during all compression tests and reported as well. The results showed that pipe models including lattice wall thickness could be preferred for the applications which don’t require too high compressive strength and their specific energy absorption values were notably capable to compete with fully solid pipe structures. In particular, rib shape lattice structure had the highest elongation while the fully solid one possessed worst ductility. Lastly, it is pointed out that 3D printing method provides a great opportunity to have a foresight about production of uncommon parts by prototyping.

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A Proof of Concept Study of the Mechanical Behavior of Lattice Structures Used to Design a Shoulder Hemi-Prosthesis

Journal of Engineering and Science in Medical Diagnostics and Therapy ◽

10.1115/1.4051419 ◽

2021 ◽

Author(s):

Marinela Peto ◽

Oscar Aguilar-Rosas ◽

Erick Erick Ramirez-Cedillo ◽

Moises Jimenez ◽

Adriana Hernandez ◽

...

Keyword(s):

Mechanical Behavior ◽

Mechanical Response ◽

Mechanical Performance ◽

Cell Attachment ◽

Lattice Structure ◽

Material Model ◽

Patient Specific ◽

Hexagonal Prism ◽

Lattice Structures ◽

Proof Of Concept

Abstract Lattice structures offer great benefits when employed in medical implants for cell attachment and growth (osseointegration), minimization of stress shielding phenomena, and weight reduction. This study is focused on a proof of concept for developing a generic shoulder hemi-prosthesis, from a patient-specific case of a 46 years old male with a tumor on the upper part of his humerus. A personalized biomodel was designed and a lattice structure was integrated in its middle portion, to lighten weight without affecting humerus’ mechanical response. To select the most appropriate lattice structure, three different configurations were initially tested: Tetrahedral Vertex Centroid (TVC), Hexagonal Prism Vertex Centroid (HPVC), and Cubic Diamond (CD). They were fabricated in resin by digital light processing and its mechanical behavior was studied via compression testing and finite element modeling (FEM). The selected structure according to the results was the HPVC, which was integrated in a digital twin of the biomodel to validate its mechanical performance through FEM but substituting the bone material model with a biocompatible titanium alloy (Ti6Al4V) suitable for prostheses fabrication. Results of the simulation showed acceptable levels of Von Mises stresses (325 MPa max.), below the elastic limit of the titanium alloys, and a better response (52 MPa max.) in a model with equivalent elastic properties, with stress performance in the same order of magnitude than the showed in bone’s material model.

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