Monitoring of environmental loading effect on the steel with different plastic deformation by diffuse ultrasound

2018 ◽  
Vol 18 (2) ◽  
pp. 602-609 ◽  
Author(s):  
Fan Xie ◽  
Weibin Li ◽  
Yuxiang Zhang
Keyword(s):  
Plastic Deformation ◽  
Mechanical Load ◽  
Early Stage ◽  
Coda Wave ◽  
Temperature Dependent ◽  
Plastic Deformations ◽  
Highly Sensitive ◽  
High Manganese Steels ◽  
Velocity Changes ◽  
Diffuse Ultrasound

Diffuse ultrasound is highly sensitive to changes in mechanical properties. Based on the coda wave interferometry analysis, we investigate the environmental temperature-induced wave velocity variations in high-manganese steels with plastic deformations by diffuse ultrasound. We observe the velocity changes in the materials at test with [Formula: see text] relative resolution. We propose the temperature-dependent coefficient as the key parameter for damage assessment in the specimens with different plastic deformations. The results show that the early-stage damage caused by plastic deformation in the specimens at test varying from 6% to 14% are successfully characterized by temperature-dependent coefficients in the absence of external mechanical load. The theoretical analysis on the sensitivity of the temperature-dependent coefficient to plastic deformation as well as the potential on-site application is discussed in this article.

scholarly journals Characterizing mechanical change in metals using amplitude-modulated diffuse ultrasound

2020 ◽  
Vol 19 (6) ◽  
pp. 1894-1904
Author(s):  
Fan Xie ◽  
Yuxiang Zhang ◽  
Eric Larose ◽  
Aroune Duclos ◽  
Su Chen ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Early Stage ◽  
Ultrasonic Method ◽  
Excitation Amplitude ◽  
Coda Wave ◽  
Metallic Materials ◽  
Velocity Change ◽  
Coda Wave Interferometry ◽  
Mechanical Change ◽  
Diffuse Ultrasound

In this article, we present an ultrasonic method based on diffuse ultrasound with successive excitation amplitudes. This method provides amplitude-dependent parameters of diffuse ultrasound using coda wave interferometry, and these parameters can be used to characterize mechanical change in metallic materials. The localized mechanical change caused by an instantaneous 400°C thermal shock in a meter-scale aluminum alloy slab was characterized by measuring the diffuse-wave velocity change and decorrelation coefficient as functions of the excitation amplitude. The potential mechanisms and spatial distribution that cause the observed amplitude-dependent diffuse waveform modification are discussed. Combining the method presented here with complementary approaches will enhance the ability to nondestructively detect early-stage damage in the laboratory or in the field.

Low-Energy Ion Irradiated Silicon Nanowires: Anomalous Plastic Deformation

2018 ◽  
Vol 4 (2) ◽  
Author(s):  
Chu Rainer Kwang-Hua
Keyword(s):  
Plastic Deformation ◽  
Silicon Nanowires ◽  
Room Temperature ◽  
Transition State Theory ◽  
State Theory ◽  
Si Nanowires ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Si Nanowire ◽  
Dependent Viscosity

We adopted the verified transition state theory, which originates from the quantum chemistry approach to explain the anomalous plastic flow or plastic deformation for Si nanowires irradiated with 100 keV (at room temperature regime) Ar+ ions as well as the observed amorphization along the Si nanowire (Johannes, et al. 2015, “Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires,” Nano Lett., 15, pp. 3800–3807). We shall illustrate some formulations which can help us calculate the temperature-dependent viscosity of flowing Si in nanodomains.

Microstructure Evolution and Deformation Mechanisms of Harmonic Structure Designed Materials

2016 ◽  
Vol 879 ◽  
pp. 145-150
Author(s):  
Kei Ameyama ◽  
Sanjay Kumar Vajpai ◽  
Mie Ota
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Powder Metallurgy ◽  
Early Stage ◽  
High Strength ◽  
Plastic Instability ◽  
Structure Design ◽  
Harmonic Structure ◽  
Homogeneous Microstructure ◽  
Macro Scale

This paper presents the novel microstructure design, called Harmonic Structure, which gives structural metallic materials outstanding mechanical properties through an innovative powder metallurgy process. Homogeneous and ultra-fine grain (UFG) structure enables the materials high strength. However, such a “Homo-“ and “UFG” microstructure does not, usually, satisfy the need to be both strong and ductile, due to the plastic instability in the early stage of the deformation. As opposed to such a “Homo-and UFG“ microstructure, “Harmonic Structure” has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the harmonic structure is heterogeneous on micro-but homogeneous on macro-scales. In the present work, the harmonic structure design has been applied to pure metals and alloys via a powder metallurgy route consisting of controlled severe plastic deformation of the corresponding powders by mechanical milling or high pressure gas milling, and subsequent consolidation by SPS. At a macro-scale, the harmonic structure materials exhibited superior combination of strength and ductility as compared to their homogeneous microstructure counterparts. This behavior was essentially related to the ability of the harmonic structure to promote the uniform distribution of strain during plastic deformation, leading to improved mechanical properties by avoiding or delaying localized plastic instability.

Experimental Verification of Constitutive Equations for Creep and Plasticity Based on Overlay Models

1983 ◽  
Vol 105 (3) ◽  
pp. 277-284 ◽  
Author(s):  
P. Meijers ◽  
F. Roode
Keyword(s):  
Plastic Deformation ◽  
Room Temperature ◽  
304 Stainless Steel ◽  
Model Parameters ◽  
General Description ◽  
Time Effects ◽  
Plastic Deformations ◽  
Biaxial Load ◽  
Theoretical Predictions ◽  
Good Agreement

A general description of creep and plastic deformation based on overlay models is presented. This includes the description of time effects during plastic deformation at room temperature. A detailed procedure to obtain the model parameters is also discussed. The description has been evaluated for a large number of uniaxial and biaxial load histories on thin walled tubes. The materials involved are a 2 1/4 Cr-1 Mo steel stabilized with Niobium (WN 1.6770) and a 304 stainless steel (WN 1.4948). The theoretical predictions of the plastic deformations are found to be sufficiently accurate. The evaluation of the phenomenological description for creep shows a fairly good agreement with the real creep deformation process. Special attention requires the description of softening due to microstructural changes.

scholarly journals Orientation Dependent Mechanical Responses and Plastic Deformation Mechanisms of ZnSe Nano Films under Nanoindentation

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3014
Author(s):  
Chao Xu ◽  
Futi Liu ◽  
Chunmei Liu ◽  
Pei Wang ◽  
Huaping Liu
Keyword(s):  
Plastic Deformation ◽  
Elastic Recovery ◽  
Structural Evolution ◽  
Atomic Displacement ◽  
Deformation Mechanisms ◽  
Formation Mechanisms ◽  
Plastic Deformations ◽  
Mechanical Responses ◽  
Displacement Vectors ◽  
Dynamics Simulations

Although ZnSe has been widely studied due to its attractive electronic and optoelectronic properties, limited data on its plastic deformations are available. Through molecular dynamics simulations, we have investigated the indentations on the (001), (110), and (111) planes of ZnSe nano films. Our results indicate that the elastic modulus, incipient plasticity, elastic recovery ratio, and the structural evolutions during the indenting process of ZnSe nano films show obvious anisotropy. To analyze the correlation of structural evolution and mechanical responses, the atomic displacement vectors, atomic arrangements, and the dislocations of the indented samples are analyzed. Our simulations revealed that the plastic deformations of the indented ZnSe nano films are dominated by the nucleation and propagation of 1/2<110> type dislocations, and the symmetrically distributed prismatic loops emitted during the indenting process are closely related with the mechanical properties. By studying the evolutions of microstructures, the formation process of the dislocations, as well as the formation mechanisms of the emitted prismatic loops under the indented crystalline planes are discussed. The results presented in this work not only provide an answer for the questions about indentation responses of ZnSe nano films, but also offer insight into its plastic deformation mechanisms.

Effect of snowfalls on relative seismic velocity changes measured by ambient noise correlation

2021 ◽  
Author(s):  
Antoine Guillemot ◽  
Alec Van Herwijnen ◽  
Laurent Baillet ◽  
Eric Larose
Keyword(s):  
Snow Cover ◽  
Solid Earth ◽  
Ambient Noise ◽  
Seismic Velocity ◽  
Coda Wave ◽  
Noise Correlation ◽  
Geophysical Research ◽  
Seismic Velocity Changes ◽  
Velocity Changes ◽  
Seismic Measurements

&lt;p&gt;Seismic noise correlation is a broadly used method to monitor the subsurface, in order to detect physical processes into the surveyed medium such changes in rigidity, fluid injection or cracking &lt;sup&gt;(1)&lt;/sup&gt;. The influence of several environmental variables on measured seismic observables were studied, such as temperature, groundwater level fluctuations, and freeze-thawing cycles &lt;sup&gt;(2)&lt;/sup&gt;. In mountainous, cold temperate and polar sites, the presence of a snowcover can also affect relative seismic velocity changes (dV/V), but this relation is relatively poorly documented and ambiguous &lt;sup&gt;(3)(4)&lt;/sup&gt;. In this study, we analyzed raw seismic recordings from a snowy flat field site located above Davos (Switzerland), during one entire winter season (from December 2018 to June 2019). Our goal was to better understand the effect of snowfall and snowmelt events on dV/V measurements through both seismic and meteorological instrumentation.&lt;/p&gt;&lt;p&gt;We identified three snowfall events with a substantial response of dV/V measurements (drops of several percent between 15 and 25 Hz), suggesting a detectable change in elastic properties of the medium due to the additional fresh snow.&lt;/p&gt;&lt;p&gt;To better interpret the measurements, we used a physical model to compute frequency dependent changes in the Rayleigh wave velocity computed before and after the events. Elastic parameters of the ground subsurface were obtained from a seismic refraction survey, whereas snow cover properties were obtained from the snow cover model SNOWPACK. The decrease in dV/V due to a snowfall were well reproduced, with the same order of magnitude than observed values, confirming the importance of the effect of fresh and dry snow on seismic measurements.&lt;/p&gt;&lt;p&gt;We also observed a decrease in dV/V with snowmelt periods, but we were not able to reproduce those changes with our model. Overall, our results highlight the effect of the snowcover on seismic measurements, but more work is needed to accurately model this response, in particular for the presence of liquid water in the snowcover.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;ul&gt;&lt;li&gt;(1) Larose, E., Carri&amp;#232;re, S., Voisin, C., Bottelin, P., Baillet, L., Gu&amp;#233;guen, P., Walter, F., et al. (2015) Environmental seismology: What can we learn on earth surface processes with ambient noise? Journal of Applied Geophysics, &lt;strong&gt;116&lt;/strong&gt;, 62&amp;#8211;74. doi:10.1016/j.jappgeo.2015.02.001&lt;/li&gt; &lt;li&gt;(2) Le Breton, M., Larose, &amp;#201;., Baillet, L., Bontemps, N. &amp; Guillemot, A. (2020) Landslide Monitoring Using Seismic Ambient Noise Interferometry: Challenges and Applications. Earth-Science Reviews&lt;/li&gt; &lt;li&gt;(3) Hotovec&amp;#8208;Ellis, A.J., Gomberg, J., Vidale, J.E. &amp; Creager, K.C. (2014) A continuous record of intereruption velocity change at Mount St. Helens from coda wave interferometry. Journal of Geophysical Research: Solid Earth, &lt;strong&gt;119&lt;/strong&gt;, 2199&amp;#8211;2214. doi:10.1002/2013JB010742&lt;/li&gt; &lt;li&gt;(4) Wang, Q.-Y., Brenguier, F., Campillo, M., Lecointre, A., Takeda, T. &amp; Aoki, Y. (2017) Seasonal Crustal Seismic Velocity Changes Throughout Japan. Journal of Geophysical Research: Solid Earth, &lt;strong&gt;122&lt;/strong&gt;, 7987&amp;#8211;8002. doi:10.1002/2017JB014307&lt;/li&gt; &lt;/ul&gt;

scholarly journals Clinical Impact of Circulating Tumor Cells in Patients with Localized Prostate Cancer

Cells ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 676 ◽  
Author(s):  
Broncy ◽  
Paterlini-Bréchot
Keyword(s):  
Prostate Cancer ◽  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Early Stage ◽  
Clinical Impact ◽  
Localized Prostate Cancer ◽  
Aggressive Cancer ◽  
Highly Sensitive ◽  
Prostate Cancers ◽  
Suitable Marker

The main issue concerning localized prostate cancers is the lack of a suitable marker which could help patients’ stratification at diagnosis and distinguish those with a benign disease from patients with a more aggressive cancer. Circulating Tumor Cells (CTC) are spread in the blood by invasive tumors and could be the ideal marker in this setting. Therefore, we have compiled data from the literature in order to obtain clues about the clinical impact of CTC in patients with localized prostate cancer. Forty-three publications have been found reporting analyses of CTC in patients with non-metastatic prostate cancer. Of these, we have made a further selection of 11 studies targeting patients with clinical or pathological stages T1 and T2 and reporting the clinical impact of CTC. The results of this search show encouraging data toward the use of CTC in patients with early-stage cancer. However, they also highlight the lack of standardized methods providing a highly sensitive and specific approach for the detection of prostate-derived CTC.

Numerical Analysis for Influence of Plastic and Elastic Deformation of Rough Surfaces on PEHL for Line Contacts

Tribology ◽  
2005 ◽  
Author(s):  
R. J. Niu ◽  
P. Huang
Keyword(s):  
Plastic Deformation ◽  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Paper Analysis ◽  
Line Contact ◽  
Plastic Deformations ◽  
Rolling Contacts ◽  
Line Contacts ◽  
Elastic And Plastic Deformations ◽  
Strain Relationship

In the present paper, analysis of elasto-plasto-hydrodynamic lubrication (PEHL) in the line contact is carried out to investigate the effect of heavily loaded roll-over on the change in profile of indents. The pressure and film thickness profiles are obtained to solve the Reynolds and film thickness equations simultaneously. And, both the elastic and plastic deformations of the contact, featured with an indent, have been considered. A multi-grid numerical algorithm used in EHL of line contacts is modified and then used for the oil lubricated rolling contacts. In the program, stress and plastic deformation of the indent profile are calculated with the hardening plastic stress-strain relationship according to the theories of plasticity when pressure excesses the yield stress. The results, with and without considering plastic deformation, are compared to show the different influences on the pressure and film thickness. Analysis shows that since the plastic deformation will change the surface roughness, it will significantly change the pressure but film thickness.

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