scholarly journals An Extended Drucker Yield Criterion to Consider Tension–Compression Asymmetry and Anisotropy on Metallic Materials: Modeling and Verification

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 20
Author(s):  
Bingtao Tang ◽  
Zhongmei Wang ◽  
Ning Guo ◽  
Qiaoling Wang ◽  
Peixing Liu
Keyword(s):  
Aluminum Alloys ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Yield Function ◽  
Close Packing ◽  
Bending Test ◽  
Rolled Plate ◽  
Face Centered Cubic ◽  
Metallic Materials ◽  
Stress Invariant

Pressure sensitive asymmetric Drucker yield criterion is developed to deal with pressure dependent sheet metals for instance steels and aluminum alloys. The sensitivity to pressure is conserved by introducing three-dimensional anisotropic parameters in the first stress invariant; while the third deviatoric stress invariant is remained in odd function form to consider the strength differential effect (SDE). To describe the flow stress directionalities of metallic materials, the Drucker yield function is extended using two transformation matrix consisting of anisotropic parameters. The proposed Drucker yield criterion is utilized to predict the anisotropic yield and plastic deformation of aluminum alloys with weak SDE: AA 2090-T3 with face-centered cubic (FCC) crystal systems and AA 2008-T4 with body-centered cubic (BCC) crystal systems as well as metals with strong SDE: Zirconium clock-rolled plate with hexagonal close packing (HCP) crystal systems. The comparison between the predicted anisotropic behavior and experimental results reveals that the extended anisotropic Drucker yield criterion can precisely model the anisotropy for FCC, BCC and HCP metals. The proposed function is implemented into ABAQUS VUMAT subroutines to describe the four-point bending test which is used to consider the effect of various yield functions and material orientations on deformation behavior. The obtained contours of the cross-section, strain components distribution and also the shift of neutral layer indicate that the extended Drucker yield function can well predict the final geometric configuration of the deformed Zirconium beam.

Electromagnetic Thermal Energy Transfer in Nanoparticle Assemblies Below Diffraction Limit

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Anil Yuksel ◽  
Edward T. Yu ◽  
Michael Cullinan ◽  
Jayathi Murthy
Keyword(s):  
Three Dimensional ◽  
Close Packing ◽  
Face Centered Cubic ◽  
Copper Nanoparticle ◽  
Colloidal Solutions ◽  
Plasmonic Coupling ◽  
Nanoparticle Assemblies ◽  
Enhanced Absorption ◽  
Face Centered ◽  
Insight Into

Abstract Fabrication of micro- and nanoscale electronic components has become increasingly demanding due to device and interconnect scaling combined with advanced packaging and assembly for electronic, aerospace, and medical applications. Recent advances in additive manufacturing have made it possible to fabricate microscale, 3D interconnect structures but heat transfer during the fabrication process is one of the most important phenomena influencing the reliable manufacturing of these interconnect structures. In this study, optical absorption and scattering by three-dimensional (3D) nanoparticle packings are investigated to gain insight into micro/nano heat transport within the nanoparticles. Because drying of colloidal solutions creates different configurations of nanoparticles, the plasmonic coupling in three different copper nanoparticle packing configurations was investigated: simple cubic (SC), face-centered cubic (FCC), and hexagonal close packing (HCP). Single-scatter albedo (ω) was analyzed as a function of nanoparticle size, packing density, and configuration to assess effect for thermo-optical properties and plasmonic coupling of the Cu nanoparticles within the nanoparticle packings. This analysis provides insight into plasmonically enhanced absorption in copper nanoparticle particles and its consequences for laser heating of nanoparticle assemblies.

scholarly journals A Micromechanical Model of Additively Manufactured Aluminum Alloys

2019 ◽  
Vol 221 ◽  
pp. 01016
Author(s):  
Evgeniya Emelianova ◽  
Varvara Romanova ◽  
Olga Zinovieva ◽  
Ruslan Balokhonov ◽  
Aleksandr Zinoviev ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Plastic Anisotropy ◽  
Micromechanical Model ◽  
Three Dimensional ◽  
Face Centered Cubic ◽  
Melt Pool ◽  
Grain Structures ◽  
Face Centered ◽  
Three Dimensional Models ◽  
Packing Method

A micromechanical model is developed to predict the deformation behavior of additively manufactured aluminum alloys. Three-dimensional models of grain structures typical for different microregions of the melt pool are generated by the step-by-step packing method. A crystal plasticity-based constitutive model accounting for the elastic-plastic anisotropy of face-centered cubic crystals is employed to simulate the microscale deformation in an additively manufactured aluminum alloy under loading. The grain shape and texture effects on the plastic strain localization patterns are analyzed.

Thermal Energy Transport Below the Diffraction Limit in Close-Packed Metal Nanoparticles

2017 ◽  
Author(s):  
Anil Yuksel ◽  
Michael Cullinan ◽  
Jayathi Murthy
Keyword(s):  
Energy Transport ◽  
Three Dimensional ◽  
Close Packing ◽  
Face Centered Cubic ◽  
Copper Nanoparticle ◽  
Colloidal Solutions ◽  
Plasmonic Coupling ◽  
Enhanced Absorption ◽  
Face Centered ◽  
Insight Into

Fabrication of micro and nanoscale electronic components has become increasingly demanding due to device and interconnect scaling combined with advanced packaging and assembly for electronic, aerospace and medical applications. Recent advances in additive manufacturing have made it possible to fabricate microscale, 3D interconnect structures but heat transfer during the fabrication process is one of the most important phenomena influencing the reliable manufacturing of these interconnect structures. In this study, optical absorption and scattering by three-dimensional (3D) nanoparticle packings are investigated to gain insight into micro/nano heat transport within the nanoparticles. Because drying of colloidal solutions creates different configurations of nanoparticles, the plasmonic coupling in three different copper nanoparticle packing configurations were investigated: simple cubic (SC), face-centered cubic (FCC) and hexagonal close packing (HCP). Single-scatter albedo (ω) was analyzed as a function of nanoparticle size, packing density, and configuration to assess effect for thermo-optical properties and plasmonic coupling of the Cu nanoparticles within the nanoparticle packings. This analysis provides insight into plasmonically enhanced absorption in copper nanoparticle particles and its consequences for laser heating of nanoparticle assemblies.

Epitaxial Ni nanoparticles on CaF2(001), (110) and (111) surfaces studied by three-dimensional RHEED, GIXD and GISAXS reciprocal-space mapping techniques

2017 ◽  
Vol 50 (3) ◽  
pp. 830-839 ◽  
Author(s):  
S. M. Suturin ◽  
V. V. Fedorov ◽  
A. M. Korovin ◽  
N. S. Sokolov ◽  
A. V. Nashchekin ◽  
...  
Keyword(s):  
Lattice Structure ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
High Energy ◽  
Reciprocal Space ◽  
Mapping Technique ◽  
Face Centered Cubic ◽  
X Ray ◽  
Cubic Lattice ◽  
Face Centered

The development of growth techniques aimed at the fabrication of nanoscale heterostructures with layers of ferroic 3dmetals on semiconductor substrates is very important for their potential usage in magnetic media recording applications. A structural study is presented of single-crystal nickel island ensembles grown epitaxially on top of CaF2/Si insulator-on-semiconductor heteroepitaxial substrates with (111), (110) and (001) fluorite surface orientations. The CaF2buffer layer in the studied multilayer system prevents the formation of nickel silicide, guides the nucleation of nickel islands and serves as an insulating layer in a potential tunneling spin injection device. The present study, employing both direct-space and reciprocal-space techniques, is a continuation of earlier research on ferromagnetic 3dtransition metals grown epitaxially on non-magnetic and magnetically ordered fluorides. It is demonstrated that arrays of stand-alone faceted nickel islands with a face-centered cubic lattice can be grown controllably on CaF2surfaces of (111), (110) and (001) orientations. The proposed two-stage nickel growth technique employs deposition of a thin seeding layer at low temperature followed by formation of the islands at high temperature. The application of an advanced three-dimensional mapping technique exploiting reflection high-energy electron diffraction (RHEED) has proved that the nickel islands tend to inherit the lattice orientation of the underlying fluorite layer, though they exhibit a certain amount of {111} twinning. As shown by scanning electron microscopy, grazing-incidence X-ray diffraction (GIXD) and grazing-incidence small-angle X-ray scattering (GISAXS), the islands are of similar shape, being faceted with {111} and {100} planes. The results obtained are compared with those from earlier studies of Co/CaF2epitaxial nanoparticles, with special attention paid to the peculiarities related to the differences in lattice structure of the deposited metals: the dual-phase hexagonal close-packed/face-centered cubic lattice structure of cobalt as opposed to the single-phase face-centered cubic lattice structure of nickel.

scholarly journals Convolutional neural network-assisted recognition of nanoscale L12 ordered structures in face-centred cubic alloys

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yue Li ◽  
Xuyang Zhou ◽  
Timoteo Colnaghi ◽  
Ye Wei ◽  
Andreas Marek ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Chemical Species ◽  
Atom Probe ◽  
Local Order ◽  
Face Centered Cubic ◽  
Ordered Structure ◽  
Ordered Structures ◽  
Distribution Maps ◽  
Structure Recognition ◽  
Fcc Alloys

AbstractNanoscale L12-type ordered structures are widely used in face-centered cubic (FCC) alloys to exploit their hardening capacity and thereby improve mechanical properties. These fine-scale particles are typically fully coherent with matrix with the same atomic configuration disregarding chemical species, which makes them challenging to be characterized. Spatial distribution maps (SDMs) are used to probe local order by interrogating the three-dimensional (3D) distribution of atoms within reconstructed atom probe tomography (APT) data. However, it is almost impossible to manually analyze the complete point cloud (>10 million) in search for the partial crystallographic information retained within the data. Here, we proposed an intelligent L12-ordered structure recognition method based on convolutional neural networks (CNNs). The SDMs of a simulated L12-ordered structure and the FCC matrix were firstly generated. These simulated images combined with a small amount of experimental data were used to train a CNN-based L12-ordered structure recognition model. Finally, the approach was successfully applied to reveal the 3D distribution of L12–type δ′–Al3(LiMg) nanoparticles with an average radius of 2.54 nm in a FCC Al-Li-Mg system. The minimum radius of detectable nanodomain is even down to 5 Å. The proposed CNN-APT method is promising to be extended to recognize other nanoscale ordered structures and even more-challenging short-range ordered phenomena in the near future.

scholarly journals Three-dimensional organization of Drosophila melanogaster interphase nuclei. I. Tissue-specific aspects of polytene nuclear architecture.

1987 ◽  
Vol 104 (6) ◽  
pp. 1455-1470 ◽  
Author(s):  
M Hochstrasser ◽  
J W Sedat
Keyword(s):  
Drosophila Melanogaster ◽  
Three Dimensional ◽  
Nuclear Architecture ◽  
Close Packing ◽  
Prothoracic Gland ◽  
Cell Type ◽  
Interphase Chromosome ◽  
Tissue Specific ◽  
Spatial Domains ◽  
Four Levels

Interphase chromosome organization in four different Drosophila melanogaster tissues, covering three to four levels of polyteny, has been analyzed. The results are based primarily on three-dimensional reconstructions from unfixed tissues using a computer-based data collection and modeling system. A characteristic organization of chromosomes in each cell type is observed, independent of polyteny, with some packing motifs common to several or all tissues and others tissue-specific. All chromosomes display a right-handed coiling chirality, despite large differences in size and degree of coiling. Conversely, in each cell type, the heterochromatic centromeric regions have a unique structure, tendency to associate, and intranuclear location. The organization of condensed nucleolar chromatin is also tissue-specific. The tightly coiled prothoracic gland chromosomes are arrayed in a similar fashion to the much larger salivary gland chromosomes described previously, having polarized orientations, nonintertwined spatial domains, and close packing of the arms of each autosome, whereas hindgut and especially the unusually straight midgut chromosomes display striking departures from these regularities. Surprisingly, gut chromosomes often appear to be broken in the centric heterochromatin. Severe deformations of midgut nuclei observed during gut contractions in living larvae may account for their unusual properties. Finally, morphometric measurements of chromosome and nuclear dimensions provide insights into chromosome growth and substructure and also suggest an unexpected parallel with diploid chromatin organization.

Coupled Thermomechanical Modeling of Small Volume FCC Metals

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Danial Faghihi ◽  
George Z. Voyiadjis ◽  
Taehyo Park
Keyword(s):  
Small Volume ◽  
Bulk Material ◽  
Yield Function ◽  
Face Centered Cubic ◽  
State Variables ◽  
Transient Time ◽  
Cubic Model ◽  
Temperature Variable ◽  
Fast Transient ◽  
Face Centered

The mechanical and thermal behavior of small volume metallic compounds on the fast transient time are addressed in this work through developing a thermodynamically consistent nonlocal framework. In this regard, an enhanced gradient plasticity theory is coupled with the application of the micromorphic approach to the temperature variable. The yield function of the VA–FCC (Voyiadjis Abed Face Centered Cubic) model based on the concept of thermal activation energy and the dislocations interaction mechanisms including nonlinear hardening is taken into consideration in the derivation. The effect of the material microstructural interface between two materials is also incorporated in the formulation with both temperature and rate effects. In order to accurately address the strengthening and hardening mechanisms, the theory is developed based on the decomposition of the mechanical state variables into energetic and dissipative counterparts which provided the constitutive equations to have both energetic and dissipative gradient length scales for the bulk material and the interface. Moreover, the nonlocal evolution of temperature is addressed by incorporating the microstructural interaction effect in the fast transient process using two time scales in the microscopic heat equation.

Overstraining of flush plain cross-bored cylinders

2004 ◽  
Vol 218 (2) ◽  
pp. 143-153 ◽  
Author(s):  
J M Kihiu ◽  
G O Rading ◽  
S M Mutuli
Keyword(s):  
Finite Element Method ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Yield Condition ◽  
Solution Technique ◽  
Stress Distributions ◽  
Dimensional Finite Element ◽  
Von Mises ◽  
Three Dimensional Finite Element ◽  
Incremental Theory Of Plasticity

A three-dimensional finite element method computer program was developed to establish the elastic-plastic, residual and service stress distributions in thick-walled cylinders with flush and non-protruding plain cross bores under internal pressure. The displacement formulation and eight-noded brick isoparametric elements were used. The incremental theory of plasticity with a 5 per cent yield condition (an element is assumed to have yielded when the effective stress is within 5 per cent of the material yield stress) and von Mises yield criterion were assumed. The frontal solution technique was used. The incipient yield pressure and the pressure resulting in a 0.3 per cent overstrain ratio were established for various cylinder thickness ratios and cross bore-main bore radius ratios. For a thickness ratio of 2.25 and a cross bore-main bore radius ratio of 0.1, the stresses were determined for varying overstrain and an optimum overstrain ratio of 37 per cent was established. To find the accuracy of the results, the more stringent yield condition of 0.5 per cent was also considered. The benefits of autofrettage were presented and alternative autofrettage and yield condition procedures proposed.

scholarly journals Utilization of rapid prototyping technology for the fabrication of an orthopedic shoe inserts for foot pain reprieve using thermo-softening viscoelastic polymers: A novel experimental approach

2020 ◽  
Vol 53 (3-4) ◽  
pp. 519-530
Author(s):  
Shubham Sharma ◽  
Jujhar Singh ◽  
Harish Kumar ◽  
Abhinav Sharma ◽  
Vivek Aggarwal ◽  
...  
Keyword(s):  
Rapid Prototyping ◽  
Thermoplastic Polyurethane ◽  
Research Work ◽  
Testing Machine ◽  
Three Dimensional ◽  
Hardness Test ◽  
Thermoplastic Elastomer ◽  
Bending Test ◽  
Foot Orthosis ◽  
Orthotic Insoles

This research work has been completed by concentrating on the structure of inserts for foot orthosis fabricated by utilizing rapid prototyping technology. Thermoplastic elastomer and thermoplastic polyurethane are the most commonly used materials that are being used in customized three-dimensional printed orthotic insoles, which are comfortable and prevent the user in many foot disorders. Thermo-softening viscoelastic polymers, explicitly Filaflex and Ninjaflex, have been printed by utilizing Flash Forge three-dimensional printers to evaluate the mechanical properties of specimens with alterations of the percentage rate fill-up design replicas. The results are compared on the basis of hardness test, flexural/bending test, and tensile test using Durometer and Universal Testing Machine (UTM). It has also been observed that the most significant effecting factor is infill density.

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