scholarly journals On the Critical Resolved Shear Stress and its Importance in the Fatigue Performance of Steels and other Metals with Different Crystallographic Structures

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 883 ◽  
Author(s):  
Marijo Mlikota ◽  
Siegfried Schmauder
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Fatigue Limit ◽  
Crystallographic Structure ◽  
Face Centered Cubic ◽  
High Fatigue ◽  
Steel Aisi ◽  
Crystallographic Structures ◽  
Set Up ◽  
Critical Resolved Shear Stress

This study deals with the numerical estimation of the fatigue life represented in the form of strength-life (S-N, or Wöhler) curves of metals with different crystallographic structures, namely body-centered cubic (BCC) and face-centered cubic (FCC). Their life curves are determined by analyzing the initiation of a short crack under the influence of microstructure and subsequent growth of the long crack, respectively. Micro-models containing microstructures of the materials are set up by using the finite element method (FEM) and are applied in combination with the Tanaka-Mura (TM) equation in order to estimate the number of cycles required for the crack initiation. The long crack growth analysis is conducted using the Paris law. The study shows that the crystallographic structure is not the predominant factor that determines the shape and position of the fatigue life curve in the S-N diagram, but it is rather the material parameter known as the critical resolved shear stress (CRSS). Even though it is an FCC material, the investigated austenitic stainless steel AISI 304 shows an untypically high fatigue limit (208 MPa), which is higher than the fatigue limit of the BCC vanadium-based micro-alloyed forging steel AISI 1141 (152 MPa).

On the Critical Resolved Shear Stress and its Importance in the Fatigue Performance of Steels and other Metals with Different Crystallographic Structures

2022 ◽  
pp. 37-65
Author(s):  
M. Mlikota
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Fatigue Limit ◽  
High Fatigue ◽  
Steel Aisi ◽  
Crystallographic Structures ◽  
Face Centered ◽  
Set Up ◽  
Number Of Cycles ◽  
Critical Resolved Shear Stress

This study deals with the numerical estimation of the fatigue life represented in the form of strength-life (S-N, or Wöhler) curves of metals with different crystallographic structures, namely body-centered cubic (BCC) and face-centered cubic (FCC). Their life curves are determined by analyzing the initiation of a short crack under the influence of microstructure and subsequent growth of the long crack, respectively. Micro-models containing microstructures of the materials are set up by using the finite element method (FEM) and are applied in combination with the Tanaka-Mura (TM) equation in order to estimate the number of cycles required for the crack initiation. The long crack growth analysis is conducted using the Paris law. The study shows that the crystallographic structure is not the predominant factor that determines the shape and position of the fatigue life curve in the S-N diagram, but it is rather the material parameter known as the critical resolved shear stress (CRSS). Even though it is an FCC material, the investigated austenitic stainless steel AISI 304 shows an untypically high fatigue limit (208 MPa), which is higher than the fatigue limit of the BCC vanadium-based micro-alloyed forging steel AISI 1141 (152 MPa).

scholarly journals Neighborhood M-Polynomial of Crystallographic Structures

2020 ◽  
Vol 11 (2) ◽  
pp. 9372-9381
Keyword(s):  
Cuprous Oxide ◽  
Topological Indices ◽  
Crystallographic Structure ◽  
Face Centered Cubic ◽  
Mathematical Chemistry ◽  
Fcc Lattice ◽  
The Face ◽  
Crystallographic Structures ◽  
Face Centered

The mathematical chemistry is wealthy, having tools such as polynomials and functions that can predict the properties of compounds. The M-polynomial is one of them which yields degree-based topological indices. In this work, we define the neighborhood M-polynomial to obtain neighborhood degree-based topological indices. Further, we compute some neighborhood degree-based topological indices of the face-centered cubic (fcc) lattice and the crystallographic structure of cuprous oxide (〖Cu〗_2 O) using the neighborhood M-polynomial approach. Also, the results are shown graphically.

A Heparin-coated Circuit Maintains Platelet Aggregability in Response to Shear Stress in an In Vitro Model of Cardiopulmonary Bypass

1998 ◽  
Vol 80 (09) ◽  
pp. 437-442 ◽  
Author(s):  
I. Hioki ◽  
K. Onoda ◽  
T. Shimono ◽  
H. Shimpo ◽  
K. Tanaka ◽  
...  
Keyword(s):  
Shear Stress ◽  
Cardiopulmonary Bypass ◽  
Membrane Skeleton ◽  
Platelet Glycoprotein ◽  
Platelet Surface ◽  
Platelet Aggregability ◽  
Vitro Model ◽  
Platelet Defects ◽  
Set Up

SummaryAlterations in platelet aggregability may play a role in the pathogenesis of qualitative platelet defects associated with cardiopulmonary bypass (CPB). We circulated fresh heparinized whole blood through tubing sets coated with heparin (C group, n = 10) and through non-coated sets (N group, n = 10) as a simulated CPB circuit. Shear stress (108 dyne/cm2)-induced platelet aggregation (hSIPA), plasma von Willebrand factor (vWF) activity and platelet glycoprotein (GP) Ib expression were measured, before, during, and after this in vitro set up of circulation. In the two groups, the extent of hSIPA significantly decreased during circulation and was partially restored after circulation. Decreases in the extent of hSIPA were significantly less with use of heparin-coated circuits. There was an equivalent reduction in plasma vWF activity, in the two groups. Expression of platelet surface GP Ib decreased significantly during circulation and recovered after circulation. Reduction of surface GP Ib expression during circulation was significantly less in the C group than that in the N group. Decrease in surface GP Ib expression correlated (r = 0.88 in either group) with the magnitude of hSIPA, in the two groups. The progressive removal of surface GP Ib was mainly attributed to redistribution of GP Ib from the membrane skeleton into the cytoskeleton. Our observations suggest that use of heparin-coated circuits partly blocks the reduction of hSIPA, as a result of a lesser degree of redistribution of GP Ib.

scholarly journals Enhanced lattice distortion, yield strength, critical resolved shear stress, and improving mechanical properties of transition-metals doped CrCoNi medium entropy alloy

RSC Advances ◽  
2021 ◽  
Vol 11 (38) ◽  
pp. 23719-23724
Author(s):  
Md. Lokman Ali
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Transition Metals ◽  
Yield Strength ◽  
Lattice Distortion ◽  
Critical Resolved Shear Stress

The effect of transition-metals (TM) addition on the mechanical properties of CrCoNi medium entropy alloys (MEAs) was investigated.

scholarly journals Green Synthesis and Characterization of Pullulan Mediated Silver Nanoparticles through Ultraviolet Irradiation

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2382 ◽  
Author(s):  
Muhammad Jamshed Khan ◽  
Suriya Kumari ◽  
Kamyar Shameli ◽  
Jinap Selamat ◽  
Awis Qurni Sazili
Keyword(s):  
Silver Nanoparticles ◽  
Uv Irradiation ◽  
Irradiation Time ◽  
Edible Films ◽  
Crystallographic Structure ◽  
Face Centered Cubic ◽  
Selected Area Electron Diffraction ◽  
Vis Spectroscopy ◽  
Face Centered ◽  
Average Lattice

Nanoparticles (NPs) are, frequently, being utilized in multi-dimensional enterprises. Silver nanoparticles (AgNPs) have attracted researchers in the last decade due to their exceptional efficacy at very low volume and stability at higher temperatures. Due to certain limitations of the chemical method of synthesis, AgNPs can be obtained by physical methods including sun rays, microwaves and ultraviolet (UV) radiation. In the current study, the synthesis of pullulan mediated silver nanoparticles (P-AgNPs) was achieved through ultraviolet (UV) irradiation, with a wavelength of 365 nm, for 96 h. P-AgNPs were formed after 24 h of UV-irradiation time and expressed spectra maxima as 415 nm, after 96 h, in UV-vis spectroscopy. The crystallographic structure was “face centered cubic (fcc)” as confirmed by powder X-ray diffraction (PXRD). Furthermore, high resolution transmission electron microscopy (HRTEM) proved that P-AgNPs were covered with a thin layer of pullulan, with a mean crystalline size of 6.02 ± 2.37. The average lattice fringe spacing of nanoparticles was confirmed as 0.235 nm with quasi-spherical characteristics, by selected area electron diffraction (SAED) analysis. These green synthesized P-AgNPs can be utilized efficiently, as an active food and meat preservative, when incorporated into the edible films.

scholarly journals A New Set-Up to Investigate Plastic Deformation of Face Centered Cubic Metals in High Strain Rate Loading

2014 ◽  
Vol 8 (2) ◽  
Author(s):  
Ehsan Etemadi ◽  
Jamal Zamani ◽  
Alessandro Francesconi ◽  
Mohammad V. Mousavi ◽  
Cinzia Giacomuzzo
Keyword(s):  
Plastic Deformation ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Face Centered Cubic ◽  
Cubic Metals ◽  
Face Centered ◽  
Set Up ◽  
Strain Rate Loading

The Influencing Factors and Assessment Rule of Fatigue Life of Shaft Based on Product Lifecycle Management

2007 ◽  
Vol 561-565 ◽  
pp. 2253-2256 ◽  
Author(s):  
You Tang Li ◽  
Ping Ma ◽  
Jun Tian Zhao
Keyword(s):  
Fatigue Life ◽  
Influencing Factors ◽  
Axial Stress ◽  
Assessment Method ◽  
Product Lifecycle Management ◽  
Product Lifecycle ◽  
Fatigue Design ◽  
Main Factors ◽  
Set Up ◽  
Lifecycle Management

Product lifecycle management is one of the main developmental aspects of advanced manufacturing technology. Anti-fatigue design is the key content in product lifecycle management. For designing the fatigue life of shaft exactly and determining the assessment method, the influencing factors must be realized roundly. The mechanical model of shaft is set up at first, and then the main factors that affect the fatigue life of shaft is discussed, the interrelations of the main factors and the framework are founded. The assessment equation of fatigue life for shaft is put forward and the influencing coefficient of multi-axial stress to fatigue life is analyzed. The results of this paper will establish the base of anti-fatigue and assessment life of shaft.

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