scholarly journals Using gradient origamis to pre-program curvatures

2021 ◽  
Author(s):  
Reza Hedayati ◽  
Nima Roudbarian ◽  
Sara Tahmasiyan
Keyword(s):  
Lattice Structure ◽  
Unit Cell ◽  
Engineering Applications ◽  
Linear Gradient ◽  
3D Structures ◽  
Radial Gradient ◽  
Japanese Art ◽  
Out Of Plane

Origami structures are a traditional Japanese art which have recently found their way into engineering applications due to their powerful capability to transform flat 2D structures into complex 3D structures along their creases. Here, gradient Miura-ori origamis are introduced as a method to pre-program out-of-plane curvatures. Nine types of unit cell distributions in the origami lattice structure including checkered, linear gradient, concave radial gradient, convex radial gradient, and striped have been considered. These distributions of Miura-ori origami can create twisting, saddling, bending, local inflation, and wavy shapes, as well as their combinations when the origami lattice structure is loaded in compression.

scholarly journals Fabrication and Compressive Behavior of a Micro-Lattice Composite by High Resolution DLP Stereolithography

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 785
Author(s):  
Chow Shing Shin ◽  
Yu Chia Chang
Keyword(s):  
High Resolution ◽  
Lattice Structure ◽  
Low Cost ◽  
Hierarchical Structures ◽  
Dip Coating ◽  
Unit Cell ◽  
Digital Light Processing ◽  
Unit Cell Size ◽  
Wide Range ◽  
And Performance

Lattice structures are superior to stochastic foams in mechanical properties and are finding increasing applications. Their properties can be tailored in a wide range through adjusting the design and dimensions of the unit cell, changing the constituent materials as well as forming into hierarchical structures. In order to achieve more levels of hierarchy, the dimensions of the fundamental lattice have to be small enough. Although lattice size of several microns can be fabricated using the two-photon polymerization technique, sophisticated and costly equipment is required. To balance cost and performance, a low-cost high resolution micro-stereolithographic system has been developed in this work based on a commercial digital light processing (DLP) projector. Unit cell lengths as small as 100 μm have been successfully fabricated. Decreasing the unit cell size from 150 to 100 μm increased the compressive stiffness by 26%. Different pretreatments to facilitate the electroless plating of nickel on the lattice structure have been attempted. A pretreatment of dip coating in a graphene suspension is the most successful and increased the strength and stiffness by 5.3 and 3.6 times, respectively. Even a very light and incomplete nickel plating in the interior has increase the structural stiffness and strength by more than twofold.

Determination of Optimal Unit-Cell Size of Homogeneous Conformal Unit-Cell Lattice Structure Using Solid Shape Matching

2016 ◽  
Author(s):  
Mahmoud A. Alzahrani ◽  
Seung-Kyum Choi
Keyword(s):  
Cell Size ◽  
Solid Body ◽  
Strain Energy ◽  
Lattice Structure ◽  
Weight Ratio ◽  
Unit Cell ◽  
Optimal Size ◽  
Lattice Structures ◽  
Unit Cell Size ◽  
Unit Cells

With rapid developments and advances in additive manufacturing technology, lattice structures have gained considerable attention. Lattice structures are capable of providing parts with a high strength to weight ratio. Most work done to reduce computational complexity is concerned with determining the optimal size of each strut within the lattice unit-cells but not with the size of the unit-cell itself. The objective of this paper is to develop a method to determine the optimal unit-cell size for homogenous periodic and conformal lattice structures based on the strain energy of a given structure. The method utilizes solid body finite element analysis (FEA) of a solid counter-part with a similar shape as the desired lattice structure. The displacement vector of the lattice structure is then matched to the solid body FEA displacement results to predict the structure’s strain energy. This process significantly reduces the computational costs of determining the optimal size of the unit cell since it eliminates FEA on the actual lattice structure. Furthermore, the method can provide the measurement of relative performances from different types of unit-cells. The developed examples clearly demonstrate how we can determine the optimal size of the unit-cell based on the strain energy. Moreover, the computational cost efficacy is also clearly demonstrated through comparison with the FEA and the proposed method.

scholarly journals Experimental and Numerical Analysis of Additively Manufactured Inconel 718 Coupons With Lattice Structure

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Sarwesh Parbat ◽  
Zheng Min ◽  
Li Yang ◽  
Minking Chyu
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Pressure Drop ◽  
Inconel 718 ◽  
Lattice Structure ◽  
Unit Cell ◽  
Common Vertex ◽  
Constant Wall Temperature ◽  
Near Surface ◽  
Smooth Channel

Abstract In the present paper, two lattice geometries suitable for near surface and double wall cooling were developed and tested. The first type of unit cell consisted of six ligaments of 0.5 mm diameter joined at a common vertex near the middle. The second type of unit cell was derived from the first type by adding four mutually perpendicular ligaments in the middle plane. Two lattice configurations, referred to as L1 and L2, respectively, were obtained by repeating the corresponding unit cell in streamwise and spanwise directions in an inline fashion. Test coupons consisting of these lattice geometries embedded inside rectangular cooling channel with dimensions of 2.54 mm height, 38.07 mm width, and 38.1 mm in length were fabricated using Inconel 718 powder and selective laser sintering (SLS) process. The heat transfer and pressure drop performance was then evaluated using steady-state tests with constant wall temperature boundary condition and for channel Reynolds number ranging from 2800 to 15,000. The lattices depicted a higher heat transfer compared with a smooth channel and both the heat transfer and pressure drop increased with a decrease in the porosity from L1 to L2. Steady-state conjugate numerical results revealed formation of prominent vortical structures in the inter-unit cell spaces, which diverted the flow toward the top end wall and created an asymmetric heat transfer between the two end walls. In conclusion, these lattice structures provided an augmented heat transfer while favorably redistributing the coolant within channel.

Rapid Modeling and Design Optimization of Multi-Topology Lattice Structure Based on Unit-Cell Library

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Yuan Liu ◽  
Shurong Zhuo ◽  
Yining Xiao ◽  
Guolei Zheng ◽  
Guoying Dong ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Lattice Structure ◽  
Structure Design ◽  
Parametric Modeling ◽  
Unit Cell ◽  
Element Analysis ◽  
Structure Generation ◽  
Cell Library ◽  
Unit Cells ◽  
Property Space

Abstract Lightweight lattice structure generation and topology optimization (TO) are common design methodologies. In order to further improve potential structural stiffness of lattice structures, a method combining the multi-topology lattice structure design based on unit-cell library with topology optimization is proposed to optimize the parts. First, a parametric modeling method to rapidly generate a large number of different types of lattice cells is presented. Then, the unit-cell library and its property space are constructed by calculating the effective mechanical properties via a computational homogenization methodology. Third, the template of compromise Decision Support Problem (cDSP) is applied to generate the optimization formulation. The selective filling function of unit cells and geometric parameter computation algorithm are subsequently given to obtain the optimum lightweight lattice structure with uniformly varying densities across the design space. Lastly, for validation purposes, the effectiveness and robustness of the optimized results are analyzed through finite element analysis (FEA) simulation.

scholarly journals Thermal Resistance across Interfaces Comprising Dimensionally Mismatched Carbon Nanotube-Graphene Junctions in 3D Carbon Nanomaterials

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Jungkyu Park ◽  
Vikas Prakash
Keyword(s):  
Carbon Nanotube ◽  
Thermal Resistance ◽  
Carbon Nanomaterials ◽  
Single Layer ◽  
Unit Cell ◽  
Single Layer Graphene ◽  
Interfacial Thermal Resistance ◽  
Layer Graphene ◽  
Out Of Plane ◽  
Plane Direction

In the present study, reverse nonequilibrium molecular dynamics is employed to study thermal resistance across interfaces comprising dimensionally mismatched junctions of single layer graphene floors with (6,6) single-walled carbon nanotube (SWCNT) pillars in 3D carbon nanomaterials. Results obtained from unit cell analysis indicate the presence of notable interfacial thermal resistance in the out-of-plane direction (along the longitudinal axis of the SWCNTs) but negligible resistance in the in-plane direction along the graphene floor. The interfacial thermal resistance in the out-of-plane direction is understood to be due to the change in dimensionality as well as phonon spectra mismatch as the phonons propagate from SWCNTs to the graphene sheet and then back again to the SWCNTs. The thermal conductivity of the unit cells was observed to increase nearly linearly with an increase in cell size, that is, pillar height as well as interpillar distance, and approaches a plateau as the pillar height and the interpillar distance approach the critical lengths for ballistic thermal transport in SWCNT and single layer graphene. The results indicate that the thermal transport characteristics of these SWCNT-graphene hybrid structures can be tuned by controlling the SWCNT-graphene junction characteristics as well as the unit cell dimensions.

INTERGROWTH AND OTHER MICROSTRUCTURE FEATURES IN BCSCO SUPERCONDUCTOR

1989 ◽  
Vol 03 (02) ◽  
pp. 275-279 ◽  
Author(s):  
SHULIN WEN ◽  
JINGWEI FENG ◽  
CHENGEN LI
Keyword(s):  
Lattice Structure ◽  
Unit Cell ◽  
X Ray ◽  
Superconducting Ceramics

Three compositions of Bi-Ca-Sr-Cu-O superconducting ceramics were studied and characterized by X-ray, EDS and HREM. In addition to the basic lattice structure A1 with unit-cell of 5.41 Å, B = 5.44 Å and c = 30.8 Å, other 3 kinds of perovskite-related structures A0, A3 and A4 were found. Furthermore, a prominent structural phenomenon, the intergrowth between A1 and other perovskite-related structures (A0, A2 and A4) were found in abundance. We had some difficulties isolating pure 120 K phase; the intergrowth may be an obstacle factor.

Notizen: Molekülstruktur von Re3Cl6(Acac)3 im Feststoff / Molecular Structure of Re3Cl6(Acac)3 in the Solid State

1990 ◽  
Vol 45 (7) ◽  
pp. 1103-1104 ◽  
Author(s):  
Manfred Irmler ◽  
Gerd Meyer
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Single Crystals ◽  
Unit Cell ◽  
Slow Evaporation ◽  
Out Of Plane

Dark red single crystals of Re3Cl6(Acac)3 are obtained from a solution of “ReCl3·2H2O” in acetylacetone by slow evaporation. The unit cell (monoclinic, P21/c, a = 1687.3(9), b = 963.4(5), c = 1664.3(9) pm, β = 108.97(4)°) contains four molecules of Re3Cl6(Acac)3. Each of the bidentate Acac(—) ligands substitutes one of the in-plane terminal and one of the out-of-plane terminal ligands with respect to the Re3 triangle.

Design and Analysis of Lattice Structures for Additive Manufacturing

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Christiane Beyer ◽  
Dustin Figueroa
Keyword(s):  
Additive Manufacturing ◽  
Lattice Structure ◽  
Cost Savings ◽  
Unit Cell ◽  
Cnc Machining ◽  
Numerical Control ◽  
Full Potential ◽  
Lattice Structures ◽  
Cell Structures ◽  
Bending Load

Additive manufacturing (AM) enables time and cost savings in the product development process. It has great potential in the manufacturing of lighter parts or tools by the embedding of cellular/lattice structures that consume less material while still distributing the necessary strength. Less weight and less material consumption can lead to enormous energy and cost savings. Although AM has come a long way over the past 25–30 years since the first technology was invented, the design of parts and tools that capitalize on the technology do not yet encompass its full potential. Designing for AM requires departing from traditional design guidelines and adopting new design considerations and thought structures. Where previous manufacturing techniques (computer numerical control (CNC) machining, casting, etc.) often necessitated solid parts, AM allows for complex parts with cellular and lattice structure implementation. The lattice structure geometry can be manipulated to deliver the level of performance required of the part. The development and research of different cell and lattice structures for lightweight design is of significant interest for realizing the full potential of AM technologies. The research not only includes analysis of existing software tools to design and optimize cell structures, but it also involves design consideration of different unit cell structures. This paper gives a solid foundation of an experimental analysis of additive manufactured parts with diverse unit cell structures in compression and flexural tests. Although the research also includes theoretical finite element analysis (FEA) of the models, the results are not considered here. As an introduction, the paper briefly explains the basics of stress and strain relationship and summarizes the test procedure and methods. The tests concentrate primarily on the analysis of 3D printed polymer parts manufactured using PolyJet technology. The results show the behavior of test specimens with different cell structures under compression and bending load. However, the research has been extended and is still ongoing with an analysis of selective laser melted test specimens in aluminum alloy AlSi10Mg.

scholarly journals Constructing and Visualizing Some Common Materials

2013 ◽  
pp. 186-197
Keyword(s):  
Carbon Nanotube ◽  
Lattice Structure ◽  
3D Structures ◽  
Carbon Molecules

In this exercise, students will learn how to use a modeling program to build a lattice structure. It will teach students how to construct a sheeted material such as graphite, how to construct an intercalated compound, how to construct a fullerene (buckyball, C60) and a aza-fullerene (C48N12), and how to construct a carbon nanotube from chains of carbon molecules. It aims to improve a student’s ability to visualize 3D structures.

scholarly journals Analysis of measurements of defects in multiaxial warp knitted fabrics for CFRP composites

2021 ◽  
Author(s):  
Diane Suk-Ching Liu
Keyword(s):  
Image Analysis ◽  
Standard Deviation ◽  
Carbon Fibre ◽  
Compression Strength ◽  
Cell Model ◽  
Unit Cell ◽  
Sample Standard Deviation ◽  
Cfrp Laminates ◽  
Laboratory Results ◽  
Out Of Plane

Multiaxial Warp Knitted (MWK) Fabrics are used to create Carbon Fibre Reinforced Plastic (CFRP) laminates. In contrast to Prepregs, CFRP laminates made with MWK fabrics are of interest because they could lower costs and processing time by being already constructed with multiple layers and through the use of a hot air oven instead of an autoclave. Defect in the form of fibre angle orientation plays an important role in the compression strength for laminates made with MWK fabrics. The in-plane and out-of-plane waviness of the fibres were characterised by the standard deviation of the angular waviness: sample Standard deviation of Fibre In-plane (SFI) and the sample Standard deviation of Fibre Out-of-plane (SFO). The SFI value was found in two ways: analysis (Multiple Field Image Analysis (MFIA) technique) software and Fibre Image Analysis software. Measurements of the holes in the carbon fibre textile, colloquially known as “fisheyes,” caused by sewing the textile together were also gathered. The SFI, SFO, and “fisheye” dimensions were together used in the FMB-PMB model and the Unit Cell Model to calculate the compression strength. These predicted compression strengths were compared to the laboratory results. Also, a reliability model was developed to find R, the reliability of each textile, to be used as a textile classification tool. It has been found that the compression strength predictions found using analysis and Fibre Image Analysis yielded similar results, with predictions from analysis closer to the laboratory results. The R value yielded a positive correlation with the results from analysis. A large percentage of difference between the predicted and the actual compression strength was observed for some textiles. This could be attributed to the inherent lack of regularity for some of the examined textiles and variability in determining the SFI and “fisheye” parameters. Improvements would involve devising rules and methods to determine the SFI and “fisheye” parameters, modifying the FMB-PMB and Unit Cell Models, and making the analysis process faster and more applicable for on-line quality process control.

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