Numerical Investigation on Polar Effects in Localized Shear Zone

2010 ◽  
Vol 452-453 ◽  
pp. 381-384
Author(s):  
Babak Ebrahimian ◽  
Asadollah Noorzad
Keyword(s):  
Shear Zone ◽  
Granular Layer ◽  
Large Deformations ◽  
Characteristic Length ◽  
Granular Soil ◽  
Volume Changes ◽  
Mean Grain Size ◽  
The Mean ◽  
Updated Lagrangian ◽  
Cosserat Rotations

Numerical simulations related to polar effects in an infinite extended granular layer under shearing movement and constant vertical pressure are presented. The mechanical behavior of cohesionless granular soil is described within the framework of micro-polar (Cosserat) continuum and using an elasto-plastic constitutive relation. The influence of Cosserat rotations and couple stresses are taken into account using the mean grain size as characteristic length. Finite element method in Updated Lagrangian (UL) frame is used to consider large deformations during calculations. The numerical results demonstrate that for large shearing movement, the shear deformations within the granular layer are localized into a narrow zone. The FE-calculations indicate that the polar effects manifest by the appearance of noticeable grain rotations, high void ratios, pronounced volume changes within the localized shear zone.

Digital volumetric measurements based on 3D scans of the lower limb: A valid and reproducible method for evaluation in lymphedema therapy. (Preprint)

2019 ◽  
Author(s):  
Daniel Schiltz ◽  
Natalie Kiermeier ◽  
Dominik Eibl ◽  
Christoph Koch ◽  
Karolina Müller ◽  
...  
Keyword(s):  
Lower Limb ◽  
Lower Leg ◽  
T Test ◽  
Volume Changes ◽  
Quick Method ◽  
Reproducible Method ◽  
The Mean ◽  
3D Scans ◽  
Paired T Test ◽  
Volumetric Measurements

BACKGROUND Exact quantification of volumetric changes of the extremities is difficult. There are several direct and indirect methods to assess extremity volume. As water displacement volumetry is rarely viable in a clinical setting and circumference measurements are prone to errors due to poor reproducibility and high inter- and intra-observer variability, an objective and easily reproducible method is indispensable. OBJECTIVE The aim of this study was to establish a standardized method based on 3D scans with defined caudal and cranial landmarks of the lower leg which allows for measurements of exactly the same body area. Furthermore, this study tests the method in terms of reproducibility and evaluates volume changes after surgical therapy in patients suffering from lymphedema. METHODS 3D-scans of the lower limb were performed with a mobile 3D-scanner. Volumetric calculation was done digitally. “Repeatability“ and “Inter-observer reliability” of digital volumetry were tested. Furthermore, the method was applied on 31 patients suffering from chronic lymphedema. ANOVA (analyses of variance) was conducted to compare the digital volumetric measurements. To assess the sensitivity to changes in digital volumetry, the mean volume of 31 patients before and 3 months after therapy were compared by a paired t-Test. RESULTS Calculations of repeatability of the volume based on 20 3D-scans of the same lower leg showed a mean volume of 2,488 ± 0,011 liters (range: 2,470 – 2,510). The mean volume of the 7 measurements of the 3 examiners did not differ significantly (F(2,18) = 1,579, p = .233). The paired t-Test showed a significant mean volume decrease of 375ml (95% CI = 245/505ml) between pre and post treatment (t (30) =5,892, p < .001). CONCLUSIONS 3D-Volumetry is a noninvasive, easy and quick method to assess volume changes of the lower leg. Other than the costs, it is reproducible and precise and therefore ideal for evolution of therapy in lymphedema.

scholarly journals Preparation of high-entropy carbides by different sintering techniques

2021 ◽  
Vol 56 (19) ◽  
pp. 11237-11247 ◽  
Author(s):  
Johannes Pötschke ◽  
Manisha Dahal ◽  
Mathias Herrmann ◽  
Anne Vornberger ◽  
Björn Matthey ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
X Ray ◽  
High Entropy ◽  
Mean Grain Size ◽  
The Mean ◽  
Gas Pressure Sintering ◽  
Hardness Values

AbstractDense (Hf, Ta, Nb, Ti, V)C- and (Ta, Nb, Ti, V, W)C-based high-entropy carbides (HEC) were produced by three different sintering techniques: gas pressure sintering/sinter–HIP at 1900 °C and 100 bar Ar, vacuum sintering at 2250 °C and 0.001 bar as well as SPS/FAST at 2000 °C and 60 MPa pressure. The relative density varied from 97.9 to 100%, with SPS producing 100% dense samples with both compositions. Grain size measurements showed that the substitution of Hf with W leads to an increase in the mean grain size of 5–10 times the size of the (Hf, Ta, Nb, Ti, V,)C samples. Vacuum-sintered samples showed uniform grain size distribution regardless of composition. EDS mapping revealed the formation of a solid solution with no intermetallic phases or element clustering. X-ray diffraction analysis showed the structure of mostly single-phase cubic high-entropy carbides. Hardness measurements revealed that (Hf, Ta, Nb, Ti, V)C samples possess higher hardness values than (Ta, Nb, Ti, V, W)C samples.

scholarly journals Fabrication of (SiC-AlN)/ZrB2 Composite with Nano-Micron Hybrid Microstructure via PCS-Derived Ceramics Route

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 334
Author(s):  
Aidong Xia ◽  
Jie Yin ◽  
Xiao Chen ◽  
Zhengren Huang ◽  
Xuejian Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Raw Materials ◽  
Secondary Phase ◽  
Pressing Temperature ◽  
Xrd Pattern ◽  
Mean Grain Size ◽  
The Mean

In this work, a (SiC-AlN)/ZrB2 composite with outstanding mechanical properties was prepared by using polymer-derived ceramics (PDCs) and hot-pressing technique. Flexural strength reached up to 460 ± 41 MPa, while AlN and ZrB2 contents were 10 wt%, and 15 wt%, respectively, under a hot-pressing temperature of 2000 °C. XRD pattern-evidenced SiC generated by pyrolysis of polycarbosilane (PCS) was mainly composed by 2H-SiC and 4H-SiC, both belonging to α-SiC. Micron-level ZrB2 secondary phase was observed inside the (SiC-AlN)/ZrB2 composite, while the mean grain size (MGS) of SiC-AlN matrix was approximately 97 nm. This unique nano-micron hybrid microstructure enhanced the mechanical properties. The present investigation provided a feasible tactic for strengthening ceramics from PDCs raw materials.

The Study on the Fabrication of Nano-Structured Steel by Cold Rolling and Annealing of Martensite

2013 ◽  
Vol 634-638 ◽  
pp. 1807-1810
Author(s):  
Guang Xu ◽  
Jing Yang ◽  
Tao Xiong ◽  
Peng Deng ◽  
Long Fei Cao
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
High Strength ◽  
Total Elongation ◽  
Plain Carbon Steel ◽  
Mean Grain Size ◽  
Cold Rolling And Annealing ◽  
The Mean ◽  
Martensite Microstructure ◽  
Very High

Sub-nano structured steel was obtained by cold rolling and annealing martensite microstructure for a plain carbon steel. The mean grain size is several hundreds nanometer. The steel has very high strength and also good total elongation.

scholarly journals Paleolimnology of Lake Yamanaka as reflected on particle-size distribution

1970 ◽  
Vol 14 ◽  
pp. 35-42 ◽  
Author(s):  
Danda Pani Adhikari
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Size Distribution ◽  
Central Japan ◽  
Size Frequency Distribution ◽  
Factors Affecting ◽  
Mean Grain Size ◽  
The Mean ◽  
Main Factors ◽  
Lake Size

A 17.63 m long bore-hole core extracted from the deepest part of Lake Yamanaka, one of the Fuji-five Lakes at the northeasternfoot of Mount Fuji, central Japan, composed of sediment with intercalations of scoria fallout deposits. The sediment of the upper11.4 m was investigated for grain-size distribution by using a laser diffraction particle size analyser. The mean grain-size profileshowed various degrees of fluctuations, both short-and long-terms, and the size-frequency distribution revealed unimodal-trimodalmixing of sediments. Changes in lake size and water depth appear to be the main factors affecting the variability in the grain-sizedistribution and properties. The lake level appears low during 7000–5000 cal BP and 2800–1150 cal BP and relatively high during5000–2800 cal BP and 1150 cal BP– present.DOI: http://dx.doi.org/10.3126/bdg.v14i0.5437Bulletin of the Department of Geology Vol.14 2011, pp.35-42 

Microstructure and Mechanical Performance of AZ31-1.7 Wt.% Si Alloy Processed by Cyclic Channel Die Compression

2010 ◽  
Vol 667-669 ◽  
pp. 457-461
Author(s):  
Wei Guo ◽  
Qu Dong Wang ◽  
Man Ping Liu ◽  
Tao Peng ◽  
Xin Tao Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Mechanical Performance ◽  
Chinese Script ◽  
Cast State ◽  
Microstructure And Mechanical Properties ◽  
Mean Grain Size ◽  
The Matrix ◽  
The Mean

Cyclic channel die compression (CCDC) of AZ31-1.7 wt.% Si alloy was performed up to 5 passes at 623 K in order to investigate the microstructure and mechanical properties of compressed alloys. The results show that multi-pass CCDC is very effective to refine the matrix grain and Mg2Si phases. After the alloy is processed for 5 passes, the mean grain size decreases from 300 μm of as-cast to 8 μm. Both dendritic and Chinese script type Mg2Si phases break into small polygonal pieces and distribute uniformly in the matrix. The tensile strength increases prominently from 118 MPa to 216 MPa, whereas the hardness of alloy deformed 5 passes only increase by 8.4% compared with as-cast state.

Evaluation of Static Liquefaction Characteristics of Saturated Loose Sand Through the Mean Grain Size and Extreme Grain Sizes

2017 ◽  
Vol 35 (5) ◽  
pp. 2079-2105 ◽  
Author(s):  
Leila Hazout ◽  
Zein El-Abidine Zitouni ◽  
Mostefa Belkhatir ◽  
Tom Schanz
Keyword(s):  
Grain Size ◽  
Loose Sand ◽  
Grain Sizes ◽  
Static Liquefaction ◽  
Mean Grain Size ◽  
The Mean

Magnetite/Nickel andMagnetite/Cobalt Multilayer Nanostructures Obtained by Pulsed Laser Deposition

2003 ◽  
Vol 777 ◽  
Author(s):  
Monica Sorescu ◽  
Agnieszka Grabias ◽  
Lucian Diamandescu
Keyword(s):  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
X Ray Diffraction ◽  
Multilayer Nanostructures ◽  
Mean Grain Size ◽  
Different Temperatures ◽  
The Mean ◽  
Metal Layers ◽  
Magnetite Phase

AbstractNanostructured magnetite/T multilayers, with T = Ni, Co, Cr, have been prepared by pulsed laser deposition. The thickness of individual magnetite and metal layers takes values in the range of 5 - 40 nm with a total multilayer thickness of 100 -120 nm. X-ray diffraction has been used to study the phase characteristics as a function of thermal treatment up to 550 °C. Small amounts of maghemite and hematite were identified together with prevailing magnetite phase after treatments at different temperatures. The mean grain size of magnetite phase increases with temperature from 12 nm at room temperature to 54 nm at 550 °C. The thermal behavior of magnetite in multilayers in comparison with powder magnetite is discussed.

Effects of Deposition Time on the Structure and Properties of AZO Thin Films Deposited on Quartz Glass by Magnetron Sputtering

2019 ◽  
Vol 807 ◽  
pp. 63-67
Author(s):  
Jing Kang Ba ◽  
Yun Zhang ◽  
Xiao Jing Wang
Keyword(s):  
Magnetron Sputtering ◽  
Quartz Glass ◽  
Deposition Time ◽  
Diffraction Peak ◽  
Visible Light Region ◽  
Structure And Properties ◽  
Light Region ◽  
Average Transmittance ◽  
Mean Grain Size ◽  
The Mean

The AZO films deposited on quartz glass by magnetron sputtering with different deposition time various from 30min to 120min.All of the obtained samples had a (002) diffraction peak range from 34.31 to 34.52°, while the mean grain size increased from 30.1nm (30min) to 56.1nm (120min) respectively. The XPS survey indicated the photoelectron peaks of Zn ,O and C elements occured. The optimal transmittance of the films reduced obviously from about 92% to 78% near 550nm with deposition time increased from 30min to 120min. And the average transmittance of AZO films prepared at 30, 60 and 90min was about 85% in the visible light region.

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