Mechanical properties and energy absorption of heterogeneous and functionally graded cellular structures

In this paper, the elastic–plastic mechanical properties of regular and functionally graded additively manufactured porous structures made by a double pyramid dodecahedron unit cell are investigated. The elastic moduli and also energy absorption are evaluated via finite element analysis. Experimental compression tests are performed which demonstrated the accuracy of numerical simulations. Next, single and multi-objective optimizations are performed in order to propose optimized structural designs. Surrogated models are developed for both elastic and plastic mechanical properties. The results show that elastic moduli and the plastic behavior of the lattice structures are considerably affected by the cell geometry and relative density of layers. Consequently, the optimization leads to a significantly better performance of both regular and functionally graded porous structures. The optimization of regular lattice structures leads to great improvement in both elastic and plastic properties. Specific energy absorption, maximum stress, and the elastic moduli in x- and y-directions are improved by 24%, 79%, 56%, and 9%, respectively, compared to the base model. In addition, in the functionally graded optimized models, specific energy absorption and normalized maximum stress are improved by 64% and 56%, respectively, in comparison with the base models.

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Impact Resistance and Energy Absorption of Functionally Graded Cellular Structures

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.69.73 ◽

2011 ◽

Vol 69 ◽

pp. 73-78 ◽

Cited By ~ 18

Author(s):

Xiao Kai Wang ◽

Zhi Jun Zheng ◽

Ji Lin Yu ◽

Chang Feng Wang

Keyword(s):

Energy Absorption ◽

Impact Resistance ◽

Functionally Graded ◽

Cellular Structures ◽

Stress Wave Propagation ◽

Initial Kinetic Energy ◽

Gradual Change ◽

Two Dimensional ◽

The One ◽

The Impact

The dynamic response of functionally graded cellular structures subjected to impact of a finite mass was investigated in this paper. Compared to a cellular structure with a uniform cell size, the one with gradually changing cell sizes may improve many properties. Based on the two-dimensional random Voronoi technique, a two-dimensional topological configuration of cellular structures with a linear density-gradient in one direction was constructed by changing the cell sizes. The finite element method using ABAQUS/Explicit code was employed to investigate the energy absorption and the influence of gradient on stress wave propagation. Results show that functionally graded cellular structures studied are superior in energy absorption to the equivalent uniform cellular structures under low initial kinetic energy impacts, and the performance of such structures can be significantly improved when the density difference is enlarged. The stress levels at the impact and support ends may be reduced by introducing a gradual change of density in cellular structures when the initial impact velocity is low.

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Controlling of Distribution of Mechanical Properties in Functionally-Graded Syntactic Foams for Impact Energy Absorption

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.729 ◽

2012 ◽

Vol 706-709 ◽

pp. 729-734 ◽

Cited By ~ 7

Author(s):

Masahiro Higuchi ◽

Tadaharu Adachi ◽

Yuto Yokochi ◽

Kenta Fujimoto

Keyword(s):

Mechanical Properties ◽

Density Distribution ◽

Energy Absorption ◽

Impact Energy ◽

Volume Fraction ◽

Functionally Graded ◽

Syntactic Foams ◽

Compression Tests ◽

Density Distributions ◽

Control Distribution

In the study, novel fabrication processes of functionally-graded (FG) syntactic foams were developed to control distribution of the mechanical properties in the FG foams for highly impact energy absorption. In order to control mechanical properties, the density distributions in FG foams were graded by floating phenomenon of the light-weight micro-balloons in matrix resin during curing process. The density distribution in the foam could be controlled by adjusting the average volume fraction and the turning procedure of the mold before grading the micro-balloons in the foam. The compression tests of the fabricated FG foams suggested that the foams had high absorption of impact energy since the foams collapsed progressively due to the grading of the density distribution.

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Mechanical properties of functionally graded 2-D cellular structures: A finite element simulation

Materials Science and Engineering A ◽

10.1016/j.msea.2008.08.040 ◽

2009 ◽

Vol 499 (1-2) ◽

pp. 434-439 ◽

Cited By ~ 64

Author(s):

A. Ajdari ◽

P. Canavan ◽

H. Nayeb-Hashemi ◽

G. Warner

Keyword(s):

Mechanical Properties ◽

Finite Element ◽

Finite Element Simulation ◽

Functionally Graded ◽

Cellular Structures ◽

Element Simulation

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Mechanical performance of additively manufactured uniform and graded porous structures based on topology-optimized unit cells

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220947119 ◽

2020 ◽

pp. 095440622094711

Author(s):

Mohsen Teimouri ◽

Masoud Asgari

Keyword(s):

Mechanical Properties ◽

Energy Absorption ◽

Mechanical Performance ◽

Functionally Graded ◽

Geometrical Parameters ◽

Lattice Structures ◽

Shell Type ◽

Two Samples ◽

Unit Cells ◽

Thin Walled

A topology optimization (TO) method is used to develop new and efficient unit cells to be used in additively manufactured porous lattice structures. Two types of unit cells including solid and thin-walled shell-type ones are introduced for generating the desired regular and functionally graded (FG) lattice structures. To evaluate structural stiffness and crushing behavior of the proposed lattice structures, their mechanical properties, and energy absorption parameters have been calculated through implementing finite element (FE) simulations on them. To validate the simulations, two samples were fabricated by a stereolithography (SLA) machine. Besides, the effects of geometrical parameters and optimizing scheme of the unit cells on the mechanical properties of the proposed structures are studied. Consequently, energy absorption parameters have been calculated and compared for both the solid and thin-walled lattice structures to evaluate their ability in energy absorption. It was found in general that for the solid lattice structures, the mechanical properties, and the crushing parameters are directly affected by porosity though in shell-type ones superior mechanical properties could be achieved even for a smaller proportion of material usage.

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Mechanical properties and energy absorption capability of functionally graded F2BCC lattice fabricated by SLM

Materials & Design ◽

10.1016/j.matdes.2018.01.059 ◽

2018 ◽

Vol 144 ◽

pp. 32-44 ◽

Cited By ~ 90

Author(s):

Dheyaa S.J. Al-Saedi ◽

S.H. Masood ◽

Muhammad Faizan-Ur-Rab ◽

Amer Alomarah ◽

P. Ponnusamy

Keyword(s):

Mechanical Properties ◽

Energy Absorption ◽

Functionally Graded

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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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Evaluation of energy absorption capabilities and mechanical properties in FDM printed PLA TPMS structures

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211039530 ◽

2021 ◽

pp. 095440622110395

Author(s):

Rakesh Sankineni ◽

Y Ravi Kumar

Keyword(s):

Mechanical Properties ◽

Energy Absorption ◽

Advanced Technology ◽

Morphological Properties ◽

Cellular Structures ◽

Poly Lactic Acid ◽

Static Compression ◽

Failure Patterns ◽

Fused Deposition ◽

The Impact

Additive manufacturing is an advanced technology used to fabricate complex geometries with unique properties like cellular structures which accommodate repeated unit cells located in the x, y and z direction. These structures can be used as infill patterns due to their self-supporting structure. Among the cellular structures, Triply Periodic Minimal Surface (TPMS) structures such as Gyroid, Diamond and Schwarz Primitive (SchwarzP) structures can be tailored to produce complex structures for various applications like tissue engineering scaffolds and replace the conventional polymeric foams. TPMS structures are designed and manufactured by using the Fused Deposition Modelling (FDM) technique using Poly-Lactic Acid (PLA) as material. Among TPMS structures, Gyroid is having a unique property like structurally symmetric which design was modified to enhance the mechanical properties. The modified Gyroid or deformed Gyroid undergone a quasi-static compression test and compare the results with Diamond and SchwarzP structures. Porosity and permeability coefficients are evaluated and an optical microscope is used to verify the fabricated components. As well as, Failure patterns of the structures were evaluated and energy absorption capabilities determined. The main objective of this paper is to evaluate the impact of design and porosity on the mechanical and morphological properties of TPMS structures. In conclusion, the deformed Gyroid has more energy absorption capability up to the 11.6% strain than other TPMS structures. After 11.6% of strain, SchwarzP structure dominates.

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