scholarly journals Design and Optimization of Graded Cellular Structures With Triply Periodic Level Surface-Based Topological Shapes

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Dawei Li ◽  
Ning Dai ◽  
Yunlong Tang ◽  
Guoying Dong ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Density Distribution ◽  
Relative Density ◽  
Cellular Structure ◽  
Scaling Laws ◽  
Functionally Graded ◽  
Cellular Structures ◽  
Level Surface ◽  
Implicit Functions ◽  
Design And Optimization ◽  
Triply Periodic

Periodic cellular structures with excellent mechanical properties widely exist in nature. A generative design and optimization method for triply periodic level surface (TPLS)-based functionally graded cellular structures is developed in this work. In the proposed method, by controlling the density distribution, the designed TPLS-based cellular structures can achieve better structural or thermal performances without increasing its weight. The proposed technique can be divided into four steps. First, the modified 3D implicit functions of the triply periodic minimal surfaces are developed to design different types of cellular structures parametrically and generate spatially graded cellular structures. Second, the numerical homogenization method is employed to calculate the elastic tensor and the thermal conductivity tensor of the cellular structures with different densities. Third, the optimal relative density distribution of the object is computed by the scaling laws of the TPLS-based cellular structures added optimization algorithm. Finally, the relative density of the numerical results of structure optimization is mapped into the modified parametric 3D implicit functions, which generates an optimum lightweight cellular structure. The optimized results are validated subjected to different design specifications. The effectiveness and robustness of the obtained structures is analyzed through finite element analysis and experiments. The results show that the functional gradient cellular structure is much stiffer and has better heat conductivity than the uniform cellular structure.

scholarly journals The Effect of Microcellular Structure on the Dynamic Mechanical Thermal Properties of High-Performance Nanocomposite Foams Made of Graphene Nanoplatelets-Filled Polysulfone

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 437
Author(s):  
Marcelo Antunes ◽  
Hooman Abbasi ◽  
José Ignacio Velasco
Keyword(s):  
Relative Density ◽  
Supercritical Co2 ◽  
Cellular Structure ◽  
High Performance ◽  
Graphene Nanoplatelets ◽  
Cellular Structures ◽  
Density Range ◽  
Specific Storage ◽  
Glass Transition Temperatures ◽  
Nanocomposite Foams

Polysulfone nanocomposite foams containing variable amounts of graphene nanoplatelets (0–10 wt%) were prepared by water vapor-induced phase separation (WVIPS) and supercritical CO2 (scCO2) dissolution. WVIPS foams with two ranges of relative densities were considered, namely, between 0.23 and 0.41 and between 0.34 and 0.46. Foams prepared by scCO2 dissolution (0.0–2.0 wt% GnP) were obtained with a relative density range between 0.35 and 0.45. Although the addition of GnP affected the cellular structure of all foams, they had a bigger influence in WVIPS foams. The storage modulus increased for all foams with increasing relative density and GnP’s concentration, except for WVIPS PSU-GnP foams, as they developed open/interconnected cellular structures during foaming. Comparatively, foams prepared by scCO2 dissolution showed higher specific storage moduli than similar WVIPS foams (same relative density and GnP content), explained by the microcellular structure of scCO2 foams. As a result of the plasticizing effect of CO2, PSU foams prepared by scCO2 showed lower glass transition temperatures than WVIPS foams, with the two series of these foams displaying decreasing values with incrementing the amount of GnP.

Behaviour of Cellular Structures under Impact Loading a Computational Study

2007 ◽  
Vol 566 ◽  
pp. 53-60 ◽  
Author(s):  
Zoran Ren ◽  
Matej Vesenjak ◽  
Andreas Öchsner
Keyword(s):  
Relative Density ◽  
Impact Loading ◽  
Cellular Structure ◽  
Computational Models ◽  
Computational Study ◽  
Base Material ◽  
Cellular Structures ◽  
Open Cell ◽  
Closed Cell ◽  
Regular Open

New multiphysical computational models for simulation of regular open and closed-cell cellular structures behaviour under compressive impact loading are presented. The behaviour of cellular structures with fluid fillers under uniaxial impact loading and large deformations has been analyzed with the explicit nonlinear finite element code LS-DYNA. The behaviour of closed-cell cellular structure has been evaluated with the use of the representative volume element, where the influence of residual gas inside the closed pores has been studied. Open-cell cellular structure was modelled as a whole to properly account for considered fluid flow through the cells, which significantly influences macroscopic behaviour of cellular structure. The fluid has been modelled by applying a Smoothed Particle Hydrodynamics (SPH) method. Computational simulations showed that the base material has the highest influence on the behaviour of cellular structures under impact conditions. The increase of the relative density and strain rate results in increase of the cellular structure stiffness. Parametrical numerical simulations have also confirmed that filler influences the macroscopic behaviour of the cellular structures which depends on the loading type and the size of the cellular structure. In open-cell cellular structures with higher filler viscosity and higher relative density, increased impact energy absorption has been observed.

Design and optimization of nonuniform cellular structures

2017 ◽  
Vol 232 (7) ◽  
pp. 1280-1293 ◽  
Author(s):  
Xin Jin ◽  
Guo-Xi Li ◽  
Meng Zhang
Keyword(s):  
Topology Optimization ◽  
Cellular Structure ◽  
Mechanical Performance ◽  
Design Method ◽  
Lightweight Design ◽  
Structure Design ◽  
Cellular Structures ◽  
Manufacturing Constraints ◽  
Element Analysis ◽  
Design And Optimization

Topology optimization and cellular structure infilling are two important approaches to achieve a lightweight design while meeting the relevant mechanical property requirements. In this work, we present a density-variable cellular structure design method combined with topology optimization while ensuring the manufacturability. The effective mechanical properties are reported as functions of the relative density to combine cellular structures with the topology optimization model. The manufacturing constraints are analyzed and expressed in topology optimization. In addition, density-variable cellular structures are rapidly modeled by mapping the topology optimization results to the relative densities of cells and via the use of user-defined features. It is shown by means of finite element analysis that the proposed design approach can improve the mechanical performance compared to the uniform cellular structure under the same weight reduction. And the choice of cell size for higher stiffness of the designed structure varies with different values of manufacturing constraints.

scholarly journals Viscoelastic Properties of Cell Structures Manufactured Using a Photo-Curable Additive Technology—PJM

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1895
Author(s):  
Tomasz Kozior ◽  
Czesław Kundera
Keyword(s):  
Viscoelastic Properties ◽  
Cellular Structure ◽  
Material Selection ◽  
Cellular Structures ◽  
Test Results ◽  
Additive Technology ◽  
Polymer Resin ◽  
Cell Structures ◽  
Relaxation Curves ◽  
The Impact

This research paper reviews the test results involving viscoelastic properties of cellular structure models made with the PolyJet Matrix—PJM additive technology. The designed test specimens were of complex cellular structure and made of three various photo-curable polymer resin types. Materials were selected taking into account the so-called “soft” and “tough” material groups. Compressive stress relaxation tests were conducted in accordance with the recommendations of standard ISO 3384, and the impact of the geometric structure shape and material selection on viscoelastic properties, as well as the most favorable geometric variants of the tested cellular structure models were determined. Mathematica and Origin software was used to conduct a statistical analysis of the test results and determine five-parameter functions approximating relaxation curves. The most favorable rheological was adopted and its mean parameters determined, which enables to match both printed model materials and their geometry in the future, to make a component with a specific rheological response. Furthermore, the test results indicated that there was a possibility of modelling cellular structures within the PJM technology, using support material as well.

scholarly journals Preparation and properties of silicone rubber materials with foam/solid alternating multilayered structures

2021 ◽  
Author(s):  
Wenhuan Zhang ◽  
Zhaoping Deng ◽  
Hongwei Yuan ◽  
Shikai Luo ◽  
Huayin Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silicone Rubber ◽  
Cellular Structure ◽  
Cellular Structures ◽  
Compressive Property ◽  
Solid Layer ◽  
Multilayered Structures ◽  
Element Analysis ◽  
Morphology And Mechanical Properties

AbstractIn this paper, silicone rubber materials with foam/solid alternating multilayered structures were successfully constructed by combining the two methods of multilayered hot-pressing and supercritical carbon dioxide (SCCO2) foaming. The cellular morphology and mechanical properties of the foam/solid alternating multilayered silicone rubber materials were systematically studied. The results show that the growth of the cell was restrained by the solid layer, resulting in a decrease in the cell size. In addition, the introduction of the solid layer effectively improved the mechanical properties of the microcellular silicone rubber foam. The tensile strength and compressive strength of the foam/solid alternating multilayered silicone rubber materials reached 5.39 and 1.08 MPa, which are 46.1% and 237.5% of the pure silicone rubber foam, respectively. Finite element analysis (FEA) was applied and the results indicate that the strength and proportion of the solid layer played important roles in the tensile strength of the foam/solid alternating multilayered silicone rubber materials. Moreover, the small cellular structures in silicone rubber foam can provided a high supporting counterforce during compression, meaning that the microcellular structure of silicone rubber foam improved the compressive property compared to that for the large cellular structure of silicone rubber foam.

Control of Hierarchically Ordered Positive and Negative Replicas of Wood Cellular Structures by Surfactant-Directed Sol-Gel Mineralization

2002 ◽  
Vol 726 ◽  
Author(s):  
Yongsoon Shin ◽  
Jun Liu ◽  
Li-Qiong Wang ◽  
Jeong Ho Chang ◽  
William D. Samuels ◽  
...  
Keyword(s):  
Silicic Acid ◽  
Cell Walls ◽  
Cellular Structure ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Silica Particles ◽  
Low Ph ◽  
Cellular Structures ◽  
Inner Surface

AbstractWe here report the synthesis of ordered ceramic materials with hierarchy produced by an in-situ mineralization of ordered wood cellular structures with surfactant-templated sol-gel at different pH. At low pH, a silicic acid is coated onto inner surface of wood cellular structure and it penetrates into pores left, where degraded lignin and hemicellulose are leached out, to form a positive replica, while at high pH the precipitating silica particles due to fast condensation clog the cells and pit structures to form a negative replica of wood. The calcined monoliths produced in different pHs contain ordered wood cellular structures, multi-layered cell walls, pits, vessels well-preserved with positive or negative contrasts, respectively. The surfactant-templated mineralization produces ordered hexagonal nanopores with 20Å in the cell walls after calcination.

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