Investigation of the structure and mechanical properties of additively manufactured Ti-6Al-4V biomedical scaffolds designed with a Schwartz primitive unit-cell

2019 ◽  
Vol 745 ◽  
pp. 195-202 ◽  
Author(s):  
Nicolas Soro ◽  
Hooyar Attar ◽  
Xinhua Wu ◽  
Matthew S. Dargusch
Keyword(s):  
Mechanical Properties ◽  
Unit Cell ◽  
Primitive Unit Cell

scholarly journals Untethered control of functional origami microrobots with distributed actuation

2020 ◽  
Vol 117 (39) ◽  
pp. 24096-24101 ◽  
Author(s):  
Larissa S. Novelino ◽  
Qiji Ze ◽  
Shuai Wu ◽  
Glaucio H. Paulino ◽  
Ruike Zhao
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Design Space ◽  
Unit Cell ◽  
Magnetic Control ◽  
Origami Engineering ◽  
Multifunctional Devices

Deployability, multifunctionality, and tunability are features that can be explored in the design space of origami engineering solutions. These features arise from the shape-changing capabilities of origami assemblies, which require effective actuation for full functionality. Current actuation strategies rely on either slow or tethered or bulky actuators (or a combination). To broaden applications of origami designs, we introduce an origami system with magnetic control. We couple the geometrical and mechanical properties of the bistable Kresling pattern with a magnetically responsive material to achieve untethered and local/distributed actuation with controllable speed, which can be as fast as a tenth of a second with instantaneous shape locking. We show how this strategy facilitates multimodal actuation of the multicell assemblies, in which any unit cell can be independently folded and deployed, allowing for on-the-fly programmability. In addition, we demonstrate how the Kresling assembly can serve as a basis for tunable physical properties and for digital computing. The magnetic origami systems are applicable to origami-inspired robots, morphing structures and devices, metamaterials, and multifunctional devices with multiphysics responses.

A MeshFree Micromechanical Analysis for Twill Composite

2016 ◽  
Vol 713 ◽  
pp. 338-341
Author(s):  
L. Li ◽  
M.H. Ferri Aliabadi
Keyword(s):  
Mechanical Properties ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Cell Stress ◽  
Unit Cell ◽  
Woven Composites ◽  
Stress Distributions ◽  
Cell Models ◽  
Stress Strain ◽  
Stress Strain Relation

This paper presents homogenization of twill woven composites. It includes presenting formulated geometrical unit cell models, establishing meshfree micromechanical and CDM models for twill woven composites. The results cover meshfree nodal distributions, meshfree yarn geometries, predicted mechanical properties, effectiveness of yarn waviness, non-linear stress-strain relation of unit cell, stress distributions inside unit cell volume, and necessary comparisons with existing literatures.

Structure of ζ-phase plutonium–uranium

1996 ◽  
Vol 52 (1) ◽  
pp. 32-37 ◽  
Author(s):  
A. C. Lawson ◽  
J. A. Goldstone ◽  
B. Cort ◽  
R. J. Martinez ◽  
F. A. Vigil ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Powder Diffraction ◽  
General Pattern ◽  
Neutron Powder Diffraction ◽  
Unit Cell ◽  
Asymmetric Unit ◽  
Space Group ◽  
Elastic Data ◽  
Primitive Unit Cell

The structure of the ζ-phase in the Pu—U system has been determined by neutron powder diffraction. The phase crystallizes in space group R{\bar 3}m with 58 atoms in the primitive unit cell and 10 atoms in the asymmetric unit. The structure is characterized by many short bonds and fits the general pattern of the light actinides. Thermal expansion and elastic data were obtained from the diffraction experiments.

Prediction of Mechanical Properties of Microcellular Plastics Using the Variational Asymptotic Method for Unit Cell Homogenization (VAMUCH) Method

2013 ◽  
Author(s):  
Emily Yu ◽  
Lih-Sheng Turng
Keyword(s):  
Mechanical Properties ◽  
Asymptotic Method ◽  
Thermoplastic Polyurethane ◽  
Three Dimensional ◽  
Unit Cell ◽  
Element Analysis ◽  
Microcellular Plastics ◽  
Variational Asymptotic ◽  
Variational Asymptotic Method ◽  
Injection Molded

This work presents the application of the micromechanical variational asymptotic method for unit cell homogenization (VAMUCH) with a three-dimensional unit cell (UC) structure and a coupled, macroscale finite element analysis for analyzing and predicting the effective elastic properties of microcellular injection molded plastics. A series of injection molded plastic samples — which included polylactic acid (PLA), polypropylene (PP), polystyrene (PS), and thermoplastic polyurethane (TPU) — with microcellular foamed structures were produced and their mechanical properties were compared with predicted values. The results showed that for most material samples, the numerical prediction was in fairly good agreement with experimental results, which demonstrates the applicability and reliability of VAMUCH in analyzing the mechanical properties of porous materials. The study also found that material characteristics such as brittleness or ductility could influence the predicted results and that the VAMUCH prediction could be improved when the UC structure was more representative of the real composition.

scholarly journals A New Biomimetic Composite Structure with Tunable Stiffness and Superior Toughness via Designed Structure Breakage

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 636
Author(s):  
Xiaohan Wang ◽  
Dongxu Li
Keyword(s):  
Mechanical Properties ◽  
Composite Structure ◽  
Composite Structures ◽  
Structure Design ◽  
Unit Cell ◽  
Geometrical Parameters ◽  
Representative Unit Cell ◽  
New Ideas ◽  
Traditional Structures ◽  
Tunable Stiffness

Mimicking natural structures has been highly pursued recently in composite structure design to break the bottlenecks in the mechanical properties of the traditional structures. Bone has a remarkable comprehensive performance of strength, stiffness and toughness, due to the intricate hierarchical microstructures and the sacrificial bonds within the organic components. Inspired by the strengthening and toughening mechanisms of cortical bone, a new biomimetic composite structure, with a designed progressive breakable internal construction mimicking the sacrificial bond, is proposed in this paper. Combining the bio-composite staggered plate structure with the sacrificial bond-mimicking construction, our new structure can realize tunable stiffness and superior toughness. We established the constitutive model of the representative unit cell of our new structure, and investigated its mechanical properties through theoretical analysis, as well as finite element modeling (FEM) and simulation. Two theoretical relations, respectively describing the elastic modulus decline ratio and the unit cell toughness promotion, are derived as functions of the geometrical parameters and the material parameters, and validated by simulation. We hope that this work can lay the foundation for the stiffness tunable and high toughness biomimetic composite structure design, and provide new ideas for the development of sacrificial bond-mimicking strategies in bio-inspired composite structures.

Twinning in A-15 Compounds

1988 ◽  
Vol 133 ◽  
Author(s):  
M. Khantha ◽  
V. Vitek ◽  
D. P. Pope
Keyword(s):  
Deformation Twinning ◽  
Unit Cell ◽  
Formula Unit ◽  
Topologically Close Packed ◽  
Primitive Unit Cell

ABSTRACTTwinning modes in topologically close-packed A-15 compounds are examined from a geometrical viewpoint. The crystallographically possible twinning modes with a shear less than a certain maximum are tabulated along with the percentage of shuffles involved for each of the modes. Based on some simple criteria, two of the most likely modes for deformation twinning are discussed in detail. The shuffle parameters usually employed to determine the percentage of lattice shuffles for a given mode have not been found to be useful in these structures because the primitive unit cell typically contains more than one formula unit. One has to examine the distribution of atoms in detail in order to determine the percentage of shuffles involved.

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