A User Study on Exploring the Sequencing of Unit Cell Design Guidelines

2017 ◽  
Author(s):  
Mohammad Fazelpour ◽  
Apurva Patel ◽  
Prabhu Shankar ◽  
Joshua D. Summers
Keyword(s):  
User Study ◽  
Cellular Materials ◽  
Design Guidelines ◽  
Unit Cell ◽  
Structural Behavior ◽  
Cell Design ◽  
Unit Cells ◽  
Meso Scale

The objective of this user study is to evaluate the effect of sequencing of unit cell design guidelines. The unit cell design guidelines support engineers in intentionally redesigning the topology and shape of unit cells for a desired structural behavior. In this study, four different unit cell design guidelines are selected to enable designers in increasing the shear flexure in meso-scale periodic cellular materials. These guidelines are not necessarily objective and may result in different modified unit cells when applied by different designers. Therefore, this user study was designed to evaluate the effect of sequencing the guidelines on the subjectivity and the modified unit cells. Twelve different sequencing sets are tested and it is found that certain sequencing of guidelines resulted in more novel ideas than other cases with less subjective guidelines.

Design for Additive Manufacturing: Effectiveness of Unit Cell Design Guidelines As Ideation Tools

2019 ◽  
Author(s):  
I’Shea Boyd ◽  
Mohammad Fazelpour
Keyword(s):  
Additive Manufacturing ◽  
Effective Properties ◽  
Cellular Materials ◽  
Design Guidelines ◽  
Unit Cell ◽  
Cell Design ◽  
Recent Approach ◽  
Wide Range ◽  
Unit Cells ◽  
High Flexibility

Abstract The periodic cellular materials are comprised of repeatable unit cells. Due to outstanding effective properties of the periodic cellular materials such as high flexibility or high stiffness at low relative density, they have a wide range of applications in lightweight structures, crushing energy absorption, compliant structures, among others. Advancement in additive manufacturing has led to opportunities for making complex unit cells. A recent approach introduced four unit cell design guidelines and verified them through numerical simulation and user studies. The unit cell design guidelines aim to guide designers to re-design the shape or topology of a unit cell for a desired structural behavior. While the guidelines were identified as ideation tools, the effectiveness of the guidelines as ideation tools has not been fully investigated. To evaluate the effectiveness of the guidelines as ideation tools, four objective metrics have been considered: novelty, variety, quality, and quantity. The results of this study reveal that the unit cell design guidelines can be considered as ideation tools. The guidelines are effective in aiding engineers in creating novel unit cells with improved shear flexibility while maintaining the effective shear modulus.

Design guidelines as ideation tools – a user study on exploring the subjectivity of unit-cell design guidelines

2018 ◽  
Vol 7 (1-2) ◽  
pp. 50-69 ◽  
Author(s):  
Mohammad Fazelpour ◽  
Apurva Patel ◽  
Prabhu Shankar ◽  
Joshua D. Summers
Keyword(s):  
User Study ◽  
Design Guidelines ◽  
Unit Cell ◽  
Cell Design

Developing Design Guidelines for Meso-Scaled Periodic Cellular Material Structures Under Shear Loading

2016 ◽  
Author(s):  
Mohammad Fazelpour ◽  
Prabhu Shankar ◽  
Joshua D. Summers
Keyword(s):  
Design Process ◽  
Effective Property ◽  
Design Guidelines ◽  
Shear Loading ◽  
Unit Cell ◽  
Cellular Material ◽  
Plane Shear ◽  
Unit Cells ◽  
Cell Topology ◽  
Shape Characteristics

Much research has been conducted on effective elastic properties of meso-scaled periodic cellular material (MPCM) structures; however, limited research is found in the literature for design guidelines to develop a unit cell (UC) topology and shape for multiple loading conditions. The current methods to design topology of unit cells has experienced limitations including numerical modeling challenges and trial-and-error associated with topology optimization and intuitive methods, respectively. To address this limitation this paper aims to develop guidelines for redesign of unit cell topology and shape under in-plane shear loading. The guidelines are intended to use design knowledge for helping engineers by providing recommendations at any stage of the design process. In this paper, the guidelines are developed by changing topology characteristics to achieve a desired effective property of a MPCM structure. The effect of individual members such as side connection and transverse connection of MPCM structure when subjected to in-plane shear loading are investigated through conducting a set of numerical simulation on UCs with similar topology and shape characteristics. Based on the simulation results, the unit cell design guidelines are developed to provide recommendations to engineers on improving shear flexure of MPCM during the design process.

A Unit Cell Design Guideline Development Method for Meso-Scaled Periodic Cellular Material Structures

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Mohammad Fazelpour ◽  
Prabhu Shankar ◽  
Joshua D. Summers
Keyword(s):  
Design Process ◽  
Guideline Development ◽  
Design Guidelines ◽  
Shear Loading ◽  
Unit Cell ◽  
Cellular Material ◽  
Cell Design ◽  
Plane Shear ◽  
Design Guideline ◽  
Development Method

Much research has been conducted on effective elastic properties of meso-scaled periodic cellular material (MPCM) structures; however, there is only limited research providing guidelines on how to develop improved unit cell (UC) topologies and shapes for a given set of loading requirements and conditions. This paper presents guidelines to improve the shear flexibility of the MPCMs while maintaining the effective shear modules by changing the topology or the shape of a unit cell. The guidelines are intended to use design knowledge for helping engineers by providing recommendations at any stage of the design process. In this paper, the guidelines are developed by changing topology characteristics to achieve a desired effective property of the MPCM structure. The effects of individual members, such as side connection, transverse connection, vertical legs, and curved beams of MPCM structure, when subjected to the in-plane shear loading are investigated through conducting a set of numerical simulation on UCs with similar topology and shape characteristics. Based on the simulation results, the unit cell design guidelines are developed to provide recommendations to engineers on improving the shear flexure of MPCM during the design process. Ultimately, a unit cell design guideline development method is offered and demonstrated by developing two new design guidelines.

Bayesian removal of noise for increased sensitivity in vector pattern recognition lattice imaging of interfaces

1993 ◽  
Vol 51 ◽  
pp. 994-995
Author(s):  
L. Fei ◽  
P. Fraundorf
Keyword(s):  
Pattern Recognition ◽  
Perfect Crystal ◽  
Unit Cell ◽  
Ion Milling ◽  
Beam Radiation ◽  
Major Interest ◽  
Unit Cells ◽  
Mapping Process ◽  
Increased Sensitivity ◽  
Electron Microscopes

Interface structure is of major interest in microscopy. With high resolution transmission electron microscopes (TEMs) and scanning probe microscopes, it is possible to reveal structure of interfaces in unit cells, in some cases with atomic resolution. A. Ourmazd et al. proposed quantifying such observations by using vector pattern recognition to map chemical composition changes across the interface in TEM images with unit cell resolution. The sensitivity of the mapping process, however, is limited by the repeatability of unit cell images of perfect crystal, and hence by the amount of delocalized noise, e.g. due to ion milling or beam radiation damage. Bayesian removal of noise, based on statistical inference, can be used to reduce the amount of non-periodic noise in images after acquisition. The basic principle of Bayesian phase-model background subtraction, according to our previous study, is that the optimum (rms error minimizing strategy) Fourier phases of the noise can be obtained provided the amplitudes of the noise is given, while the noise amplitude can often be estimated from the image itself.

scholarly journals Prediction of Effective Thermal Conductivities of Four-Directional Carbon/Carbon Composites by Unit Cells with Different Sizes

2021 ◽  
Vol 11 (3) ◽  
pp. 1171
Author(s):  
Chang Xu ◽  
Zhihong Sun ◽  
Guowei Shao
Keyword(s):  
Carbon Fiber ◽  
Longitudinal Direction ◽  
Unit Cell ◽  
Carbon Composites ◽  
Temperature Boundary ◽  
The Matrix ◽  
Unit Cells ◽  
Experimental Values ◽  
Different Diameters ◽  
Thermal Conductivities

Two-unit cells developed to predict the effective thermal conductivities of four-directional carbon/carbon composites with the finite element method are proposed in this paper. The smaller-size unit cell is formulated from the larger-size unit cell by two 180° rotational transformations. The temperature boundary conditions corresponding to the two-unit cells are derived, and the validity is verified by the temperature and heat flux distributions at specific positions of the larger-size unit cell and the smaller-size unit cell. The thermal conductivities of the carbon fiber bundles and carbon fiber rods are measured firstly. Then, combined with the properties of the matrix, the effective thermal conductivities of the four-directional carbon/carbon composites are numerically predicted. The results in transverse direction predicted by the larger-size unit cell and the smaller-size unit cell are both higher than experimental values, which are 5.8 to 6.2% and 7.3 to 8.2%, respectively. In longitudinal direction, the calculated thermal conductivities of the larger-size unit cell and the smaller-size unit cell are 6.8% and 6.2% higher than the experimental results, respectively. In addition, carbon fiber rods with different diameters are set to clarify the influence on the effective thermal conductivities of the four-directional carbon/carbon composites.

scholarly journals A Multiband Antenna Stacked with Novel Metamaterial SCSRR and CSSRR for WiMAX/WLAN Applications

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 113
Author(s):  
Rajiv Mohan David ◽  
Mohammad Saadh AW ◽  
Tanweer Ali ◽  
Pradeep Kumar
Keyword(s):  
Split Ring Resonator ◽  
Unit Cell ◽  
Ring Resonators ◽  
Split Ring ◽  
Medium Theory ◽  
High Frequency Structure Simulator ◽  
Dimension Analysis ◽  
Unit Cells ◽  
Coaxial Feed ◽  
Triple Band

This paper presents an innovative method for the design of a triple band meta-mode antenna. This unique design of antenna finds application in a particular frequency band of WLAN and WiMAX. This antenna comprises of a square complimentary split ring resonator (SCSRR), a coaxial feed, and two symmetrical comb shaped split ring resonators (CSSRR). The metamaterial unit cell SCSRR independently gains control in the band range 3.15–3.25 GHz (WiMAX), whereas two symmetrical CSSRR unit cell controls the band in the ranges 3.91–4.01 GHz and 5.79–5.94 GHz (WLAN). This design methodology and the study of the suggested unit cells structure are reviewed in classical waveguide medium theory. The antenna has a miniaturized size of only 0.213λ0 × 0.192λ0 × 0.0271λ0 (20 × 18 × 2.54 mm3, where λ0 is the free space wavelength at 3.2 GHz). The detailed dimension analysis of the proposed antenna and its radiation efficiency are also presented in this paper. All the necessary simulations are carried out in High Frequency Structure Simulator (HFSS) 13.0 tool.

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

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.

The Influence of Multiple Inclusions on the Cauchy Stress of a Spherical Particle-Reinforced Composite Under Uniaxial Loading

2014 ◽  
Author(s):  
Ke Niu ◽  
Armin Abedini ◽  
Zengtao Chen
Keyword(s):  
Spherical Particle ◽  
Single Particle ◽  
Volume Fraction ◽  
Unit Cell ◽  
Spherical Particles ◽  
Uniaxial Tensile ◽  
Cauchy Stress ◽  
Particle Volume ◽  
Volume Fractions ◽  
Unit Cells

This paper investigates the influence of multiple inclusions on the Cauchy stress of a spherical particle-reinforced metal matrix composite (MMC) under uniaxial tensile loading condition. The approach of three-dimensional cubic multi-particle unit cell is used to investigate the 15 non-overlapping identical spherical particles which are randomly distributed in the unit cell. The coordinates of the center of each particle are calculated by using the Random Sequential Adsorption algorithm (RSA) to ensure its periodicity. The models with reinforcement volume fractions of 10%, 15%, 20% and 25% are evaluated by using the finite element method. The behaviour of Cauchy stress for each model is analyzed at a far-field strain of 5%. For each reinforcement volume fraction, four models with different particle spatial distributions are evaluated and averaged to achieve a more accurate result. At the same time, single-particle unit cell and analytical model were developed. The stress-strain curves of multi-particle unit cells are compared with single-particle unit cells and the tangent homogenization model coupled with the Mori-Tanaka method. Only little scatters were found between unit cells with the same particle volume fractions. Multi-particle unit cells predict higher response than single particle unit cells. As the volume fraction of reinforcements increases, the Cauchy stress of MMCs increases.

Sign in / Sign up

Export Citation Format

Share Document