scholarly journals A Multi-Scale Approach to Predict the Impact Resistance of Braided Composites using Progress Failure

2017 ◽  
Vol 26 (1) ◽  
pp. 096369351702600
Author(s):  
Xu Lei ◽  
Khazar Hayat ◽  
Sung Kyu Ha
Keyword(s):  
Effective Properties ◽  
Impact Resistance ◽  
Unit Cell ◽  
Braided Composites ◽  
Damage Models ◽  
Multi Scale ◽  
Constituent Material ◽  
Unit Cells ◽  
Plastic Resin ◽  
The Impact

A novel multi-scale approach based on micromechanics of failure together with the progressive damage models of the fibre and matrix constituents is presented to predict the impact resistance of braided composites. The meso- and micro-scale unit-cells of the braided composites with both thermosetting and thermos-plastic resin systems, were employed, and the effective properties of the braided tows, in the meso unit cell, were updated using the micro unit cell for which the degradation of constituent material properties were incorporated.

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.

scholarly journals Multiscale Evaluation of The Elastic Behavior for The Metal-Coated Lattice Structures

2020 ◽  
Author(s):  
Sina Soleimanian ◽  
Xiang Wang ◽  
Min Chen ◽  
Yanqing Yu ◽  
Ji Li ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Film Thickness ◽  
Volume Fraction ◽  
Effective Properties ◽  
Unit Cell ◽  
Homogenization Theory ◽  
Elastic Behavior ◽  
Coating Film ◽  
Specific Modulus ◽  
The Impact

Abstract Well-developed Additive Manufacturing leads to a variety of material and structure design. With the combination of 3D printing and plating technique, metal-coated resin lattice is investigated to achieve a light weight design with minimal economic cost and admirable material properties. In this paper, numerical approaches integrated with classical homogenization theory is adopted to study the effective mechanical characterizations of the BCC (Body-Centered-Cubic) metal-coated lattices. The selection of RVE (Representative Volume Element) is discussed for obtaining objective effective properties. Moreover, the impact of unit cell rod diameter and coating film thickness are investigated. A sensitivity analysis of these two parameters is conducted based on the advanced hypercube sampling methods. The results reveal that multiple-unit-cells lead to more stable homogenized properties than single unit cell. The Increase of volume fraction may improve the elastic modulus and specific modulus remarkably. However, the increase of thickness of coating film only leads to monotonously increased elastic modulus. For this reason, there exists an optimal coating film thickness for the specific modulus of the lattice structure.

scholarly journals Aluminum Matrix Composites with Weak Particle Matrix Interfaces: Effective Elastic Properties Investigated Using Micromechanical Modeling

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6083
Author(s):  
Aharon Farkash ◽  
Brigit Mittelman ◽  
Shmuel Hayun ◽  
Elad Priel
Keyword(s):  
Elastic Properties ◽  
Effective Properties ◽  
Aluminum Matrix ◽  
Unit Cell ◽  
Micromechanical Modeling ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Element Analysis ◽  
Effective Elastic Properties ◽  
The Impact

The impact of weak particle-matrix interfaces in aluminum matrix composites (AMCs) on effective elastic properties was studied using micromechanical finite-element analysis. Both simplified unit cell representations (i.e., representative area or volume elements) and “real” microstructure-based unit cells were considered. It is demonstrated that a 2D unit cell representation provides accurate effective properties only for strong particle-matrix bond conditions, and underpredicts the effective properties (compared to 3D unit cell computations) for weak interfaces. The computations based on real microstructure of an Al–TiB2 composite fabricated using spark plasma sintering (SPS) show that, for weak interfaces, the effective elastic properties under tension are different from those obtained under compression. Computations show that differences are the result of the local stress and strain fields, and contact mechanics between particles and the matrix. Preliminary measurements of the effective elastic properties using the ultrasonic pulse-echo technique and compression experiments support the trends observed in computational analysis.

scholarly journals The impact of cryosolution thermal contraction on proteins and protein crystals: volumes, conformation and order

2018 ◽  
Vol 74 (9) ◽  
pp. 922-938 ◽  
Author(s):  
Douglas H. Juers ◽  
Christopher A. Farley ◽  
Christopher P. Saxby ◽  
Rosemary A. Cotter ◽  
Jackson K. B. Cahn ◽  
...  
Keyword(s):  
Crystal Packing ◽  
Unit Cell ◽  
Thermal Contraction ◽  
X Ray Diffraction ◽  
Solvent Content ◽  
X Ray ◽  
Macromolecular Conformation ◽  
Unit Cells ◽  
The Impact ◽  
Cell Volumes

Cryocooling of macromolecular crystals is commonly employed to limit radiation damage during X-ray diffraction data collection. However, cooling itself affects macromolecular conformation and often damages crystals via poorly understood processes. Here, the effects of cryosolution thermal contraction on macromolecular conformation and crystal order in crystals ranging from 32 to 67% solvent content are systematically investigated. It is found that the solution thermal contraction affects macromolecule configurations and volumes, unit-cell volumes, crystal packing and crystal order. The effects occur through not only thermal contraction, but also pressure caused by the mismatched contraction of cryosolvent and pores. Higher solvent-content crystals are more affected. In some cases the solvent contraction can be adjusted to reduce mosaicity and increase the strength of diffraction. Ice formation in some crystals is found to cause damage via a reduction in unit-cell volume, which is interpreted through solvent transport out of unit cells during cooling. The results point to more deductive approaches to cryoprotection optimization by adjusting the cryosolution composition to reduce thermal contraction-induced stresses in the crystal with cooling.

Effective properties of a periodic chiral arrangement of identical biaxially dielectric plates

1989 ◽  
Vol 4 (6) ◽  
pp. 1511-1514 ◽  
Author(s):  
A. Lakhtakia ◽  
V. K. Varadan ◽  
V. V. Varadan
Keyword(s):  
Electromagnetic Fields ◽  
Effective Properties ◽  
Unit Cell ◽  
Characteristic Matrix ◽  
Periodic Medium ◽  
Lyapunov Theorem ◽  
Anisotropic Plates ◽  
Left Handed ◽  
Unit Cells ◽  
Cell Thickness

A periodically inhomogeneous medium is constructed by stacking up unit cells made of (identical) structurally chiral slabs. Each structurally chiral slab is comprised of a certain number of identical biaxially anisotropic plates, the consecutive optic axes describing either a right- or a left-handed spiral. The characteristic matrix of the unit cell is obtained and used with the Floquet-Lyapunov theorem to obtain the electromagnetic fields in the periodic medium. When the unit cell thickness is very small compared to the principal wavelengths in the biaxial plates, the periodically inhomogeneous biaxial medium is shown to be equivalent to a homogeneous biaxial medium, the two optic axes of the equivalent medium being dependent on the handedness of the periodic medium.

A New Geometric Model for Three-Dimensional Braided Composites

2014 ◽  
Vol 662 ◽  
pp. 15-19 ◽  
Author(s):  
Chen Bing Ni ◽  
Gao Feng Wei
Keyword(s):  
Cross Section ◽  
Geometric Model ◽  
Geometric Analysis ◽  
Three Dimensional ◽  
Structural Features ◽  
Unit Cell ◽  
Braided Composites ◽  
Unit Cells ◽  
Analysis Models ◽  
Surface Unit Cell

According to the structural features of 3-D braided composites, the whole structure is divided into three types of sub-unit cells, these are the interior unit cell, the surface unit cell and the corner unit cell. Considering the bending of fiber bundle and the deformation of cross-section which are caused by the space fiber extrusion and twist together, the corresponding geometric analysis models for every type of sub-unit cell are established, and the engineering elastic constants of the 3-D braided composites are predicted. The results show that the calculated results well agree with the experimental results, and the effectiveness of the model is verified.

scholarly journals Influence of unit cell parameters of tetrachiral mechanical metamaterial on its effective properties

2021 ◽  
Vol 8 (1) ◽  
pp. 150-157
Author(s):  
Linar R. Akhmetshin ◽  
◽  
Igor Yu. Smolin ◽  
◽  
◽  
...  
Keyword(s):  
Rotation Angle ◽  
Effective Properties ◽  
Three Dimensional ◽  
Unit Cell ◽  
The Finite Element Method ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Chiral Structures ◽  
Unit Cells ◽  
Loading Axis

In the paper, we study the mechanical behavior of a three-dimensional chiral mechanical metamaterial using numerical modeling. A feature of chiral structures is that during their uniaxial loading a twisting is observed along the loading axis. A rod of the mechanical metamaterial composed of 3 × 3 × 9 unit cells along the corresponding three orthogonal axes. The relative strain of uniaxial compression of the sample in the simulation did not exceed 3.3%. The simulation was performed by the finite element method in a threedimensional case. Original results on the dependencies of the rotation angle and the reaction of the rigidly fixed support of the metamaterial sample on the parameters characterizing the structure of the unit cell of the metamaterial are presented in this context. All the dependencies, except one, are nonlinear with portions of large and small changes.

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.

Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Indirect Tensile ◽  
The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    

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