Regular, low density cellular structures - rapid prototyping, numerical simulation, mechanical testing (original) (raw)
Related papers
The International Journal of Advanced Manufacturing Technology, 2019
Cellular structures are promising applicants for additive manufacturing (AM), due to their best capabilities over solid ones such as high strength-to-weight ratio, having porosity, and light in weight. New vintile cellular structures and with the existing five different cellular structures namely cubic, tetrahedron, hexagon, octagon, and rhombic dodecahedron were designed and the effect of unit size, lattice topology, porosity, and optimization of cellular structures on the mechanical properties were discussed in this study. Eighty-four samples with different cell sizes, lattice topologies, and porosities were printed using VisiJet M3 Crystal material on Projet 3510 HDMax 3D printer. Then, electro-optical microscopic is used to determine the pore size. Based on predesigned cellular structures, finite element analysis (FEA) and experimental work were performed to estimate and evaluate the mechanical properties of cellular structures. Results shown that the cellular structure with vintile lattice topology performs less stress and less deformation than the other cellular structures. The experiment results were in good conformance with the result obtained from simulation. This study is not only limited to cellular structure design for biomedical applications but also compared the mechanical performance of uniform density and variable density cellular structures. Both non-optimized and optimized vintile cellular structures is finally tested with FEA and experiments have been carried out on samples fabricated by material jetting, and both results have shown that the optimized cellular structure had much less stress and lower deformation than the nonoptimized cellular structure.
Fabrication and moulding of cellular materials by rapid prototyping
International Journal of Materials and Product Technology, 2004
Many biological materials (e.g. wood, cork, bone,. . .) are based on cellular designs, since cellular architectures offer the possibility to optimise the properties (stiffness, density, strength,. . .) of a structure according to the environmental conditions the structure is exposed to. By using Rapid Prototyping it is possible to fabricate cellular materials on a similar size scale as in natural material-structures. By using appropriate moulding techniques, these structures can be fabricated out of a wide variety of materials (polymers, ceramics, composites). In this work, several RP techniques are investigated regarding their suitability for the fabrication of cellular solids. The main focus is on using direct light projection (stereolithography) in combination with gelcasting as moulding technique. Besides using commercial light-sensitive resins, a class of newly developed water-soluble resins has been evaluated regarding its usability as sacrificial mould material.
Effect of Porosity and Cell Topology on Elastic-Plastic Behavior of Cellular Structures
Procedia Structural Integrity, 2019
In this work we study the mechanical behavior of Ti6Al4V cellular structures by varying the randomness in the cell topology from regular cubic to completely random and the porosity of the structure. The porosity of the structure is altered by changing the strut thickness and the pore size to obtain a stiffness value between 0.5-12Gpa. The geometrical deviation in the structures from the asdesigned values is studied by morphological characterization. The samples are subjected to compression and tensile loading to obtain the stiffness and the elastic-plastic behavior of the samples. Finite element modelling (FEM) is carried out on the as-designed structures for both tensile and compressive loading to study the effect of deviation between the as-designed and as-built structures. FEM is also carried out for as-built regular structures, by introducing the geometrical deviation to match the porosity of the as-built structures. Comparison of FEM and experimental results indicated that the effect of cell topology depends on the porosity values. Simulation results of as-built structures demonstrated the importance of defects in the structure.
2017
The aim of this paper is to present the results of experimental investigations concerning a mechanical response of 2D regular cellular structures with different topologies in an aspect of crashworthiness behaviour. Developed by the authors, genuine topologies of 2D regular cellular structures were built with using Fused Deposition Modelling (FDM) additive manufacturing method and afterwards they were subjected to uniaxial compression tests. A wide range of structure topologies made from three commercially available polymeric materials ABSplus, Nylon12 and PC-10 were examined during carried out investigations. One of the commercially available CAD systems was used to define proposed structure topologies. It was found that the energy absorption depends on the elasticity of a structure, where high strength geometries represent linear crashworthiness behaviour with bending and cracking while flexible ones present exponential increase of deformation force due to densification of the stru...
• Triply periodic minimal surfaces (TPMS) are utilized to create new cellular materials (CMs). • The modulus and strength of three types of TPMS-CMs are found experimentally and computationally. • Post-yielding behavior of the three TPMS-CMs is reported and discussed. • Failure (buckling vs. yielding) maps are reported. In this paper, three types of triply periodic minimal surfaces (TPMS) are utilized to create novel polymeric cellular materials (CM). The TPMS architectures considered are Schwarz Primitive, Schoen IWP, and Neovius. This work investigates experimentally and computationally mechanical properties of these three TPMS-CMs. 3D printing is used to fabricate these polymeric cellular materials and their base material. Their properties are tested to provide inputs and serve as validation for finite element modeling. Two finite deformation elastic/hyperelastic-viscoplastic constitutive models calibrated based on the mechanical response of the base material are used in the computational study of the TPMS-CMs. It is shown that the specimen size of the TPMS-CMs affect their mechanical properties. Moreover, the finite element results agree with the results obtained experimentally. The Neovius-CM and IWP-CM have a similar mechanical response, and it is found that they have higher stiffness and strength than the Primitive-CM.
Study of architectural responses of 3D periodic cellular materials
Modelling and Simulation in Materials Science and Engineering, 2013
The functional properties of periodic cellular solids such as photonic and phononic crystals, nanocrystal superlattices and foams may be tuned by an applied inhomogeneous mechanical strain. A fundamental methodology to analyse the structure of periodic cellular materials is presented here and is compared directly with indentation experiments on three-dimensional microframed polymer photonic crystals. The application of single-continuumscale finite-element modelling (FEM) was impossible due to the numerous cells involved and the intricate continuum geometry within each cell. However, a method of dual-scale FEM was implemented to provide stress and displacement values on both scales by applying an upper scale continuum FEM with reference to the lower scale continuum FEM to provide coarse-grained stressstrain relationships. Architecture and orientation dependences of the periodic porous materials on the macro-/microscopic responses were investigated under different loading conditions. Our study revealed a computational tool for exploring elastic strain engineering of photonic crystals and, more broadly, may help the design of metamaterials with mechanical controllability.
IJERT-Optimum Design of Hexagonal Cellular Structures Under Thermal and Mechanical Loads
International Journal of Engineering Research and Technology (IJERT), 2020
https://www.ijert.org/optimum-design-of-hexagonal-cellular-structures-under-thermal-and-mechanical-loads https://www.ijert.org/research/optimum-design-of-hexagonal-cellular-structures-under-thermal-and-mechanical-loads-IJERTV9IS060813.pdf The concept of cellular materials is available long time ago in nature, examples of these cellular materials are, bones, wood, glass sponges, plant stems, and bird beaks. There must be good reasons for it. Researchers showed a great interest in a new class of materials with optimized properties. Two contradicting objectives are considered. A better mechanical, physical, thermal, and acoustic properties are required, as well as, low density. Sandwich structures deliver this combination of properties. They are light weight and compact structures that could be used in various applications. In this paper, the concept of sandwich structures was investigated. They are consisted of a core sandwiched between two substrates. This compact combination can achieve lightness with relatively high rigidity and stiffness. Such structures could be metallic or composite. Sandwich structures are divided into three main groups; Metal foams, periodic cellular metals and lattice structures. The difference between each type is the core formation and orientation. A hexagonal honeycomb cellular structure was studied as a compact heat exchanger that loaded with both thermal and mechanical loads. First, a comparison was carried out between different structure materials and cooling fluids. Then, optimum design curves were constructed to help for selecting the optimum cell size, cell thickness and structure height that maximize thermal and mechanical performances.
Designs
Recent developments in design and manufacturing have greatly expanded the design space for functional part production by enabling control of structural details at small scales to inform behavior at the whole-structure level. This can be achieved with cellular materials, such as honeycombs, foams and lattices. Designing structures with cellular materials involves answering an important question: What is the optimum unit cell for the application of interest? There is currently no classification framework that describes the spectrum of cellular materials, and no methodology to guide the designer in selecting among the infinite list of possibilities. In this paper, we first review traditional engineering methods currently in use for selecting cellular materials in design. We then develop a classification scheme for the different types of cellular materials, dividing them into three levels of design decisions: tessellation, element type and connectivity. We demonstrate how a biomimetic a...
Applied Sciences
Additive manufacturing (AM) has a greater potential to construct lighter parts, having complex geometries with no additional cost, by embedding cellular lattice structures within an object. The geometry of lattice structure can be engineered to achieve improved strength and extra level of performance with the advantage of consuming less material and energy. This paper provides a systematic experimental evaluation of a series of cellular lattice structures, embedded within a cylindrical specimen and constructed according to terms and requirements of ASTMD1621-16, which is standard for the compressive properties of rigid cellular plastics. The modeling of test specimens is based on function representation (FRep) and constructed by fused deposition modeling (FDM) technology. Two different test series, each having eleven test specimens of different parameters, are printed along with their replicates of 70% and 100% infill density. Test specimens are subjected to uniaxial compressive loa...