scholarly journals Minimal Invasive Diagnostic Capabilities and Effectiveness of CFRP-Patches Repairs in Long-Term Operated Metals

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 984
Author(s):  
Grzegorz Lesiuk ◽  
Bruno A. S. Pedrosa ◽  
Anna Zięty ◽  
Wojciech Błażejewski ◽  
Jose A. F. O. Correia ◽  
...  
Keyword(s):  
Minimal Invasive ◽  
Diagnostic Methods ◽  
Metallic Materials ◽  
Intensity Factors ◽  
Fatigue Lifetime ◽  
Historical Materials ◽  
Virgin State ◽  
The Subject ◽  
Diagnostic Capabilities

The paper deals with the subject of diagnostics and the quick repairs of long-term operated metallic materials. Special attention was paid to historical materials, where the structure (e.g., puddle iron) is different from modern structural steels. In such materials, the processes of microstructural degradation occur as a result of several decades of exposure, which could overpass 100 years. In some cases, their intensity can be potentially catastrophic. For this reason, the search for minimally invasive diagnostic methods is ongoing. In this paper, corrosion and fracture toughness tests were conducted, and the results of these studies were presented for two material states: post-operated and normalized (as a state “restoring” virgin state). Moreover, through the use of modern numerical methods, composite crack-resistant patches have been designed to reduce the stress intensity factors under cyclic loads. As a result, fatigue lifetime was extended (propagation phase) by more than 300%.

Inflation of a Thick-Walled Shell Which Exhibits Stress Softening

1998 ◽  
Vol 65 (1) ◽  
pp. 46-50 ◽  
Author(s):  
J. B. Haddow ◽  
J. L. Wegner
Keyword(s):  
Internal Pressure ◽  
Strain Softening ◽  
Complete Removal ◽  
Mullins Effect ◽  
Stress Softening ◽  
Permanent Set ◽  
Virgin State ◽  
Rubberlike Material ◽  
As Stress

The Mullins effect (Mullins, 1947), also known as stress softening, is exhibited by certain rubberlike materials and refers to changes of the mechanical properties, due to prior deformation. Johnson and Beatty (1995) have investigated the Mullins effect in equibiaxial tension by performing cycles of static inflation and deflation experiments on latex balloons. These experiments show that stress softening results in a decrease in the pressure necessary to inflate a balloon, and in addition, indicate inelastic effects of hysteresis and permanent set. The objective of this paper is to investigate the finite deformation static inflation from the virgin state, followed by quasi-static removal of the internal pressure, of a thick-walled homogeneous spherical shell composed of an incompressible isotropic rubberlike material which exhibits stress softening and permanent set. Since the initial inflation of the shell, due to application of an internal pressure, does not result in a homogeneous deformation, a state of residual stress is present after complete removal of the internal pressure. A procedure is presented for the determination of the response of the shell for the first cycle of inflation and deflation from the virgin state, and the analysis includes strain softening and the inelastic effects of hysteresis and permanent set. It is assumed that, for the initial static inflation of the shell from the virgin state, the internal pressure and stress distribution for a monotonically increasing internal or external radius are the same as for a hyperelastic shell, and also that the magnitude of the permanent set of an element of the material is related monotonically to the deformation at the end of the inflation.

scholarly journals Organic Contaminants and Interactions with Micro- and Nano-Plastics in the Aqueous Environment: Review of Analytical Methods

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1164
Author(s):  
Julia Reichel ◽  
Johanna Graßmann ◽  
Oliver Knoop ◽  
Jörg E. Drewes ◽  
Thomas Letzel
Keyword(s):  
Organic Contaminants ◽  
Analytical Methods ◽  
Sorption Kinetics ◽  
Aqueous Environment ◽  
Visible Spectroscopy ◽  
Differential Approach ◽  
Virgin State ◽  
Particle Size And Shape ◽  
Trace Organic Chemicals ◽  
Trace Organic

Micro- and nanoplastic particles are increasingly seen not only as contaminants themselves, but also as potential vectors for trace organic chemicals (TOrCs) that might sorb onto these particles. An analysis of the sorbed TOrCs can either be performed directly from the particle or TOrCs can be extracted from the particle with a solvent. Another possibility is to analyze the remaining concentration in the aqueous phase by a differential approach. In this review, the focus is on analytical methods that are suitable for identifying and quantifying sorbed TOrCs on micro- and nano-plastics. Specific gas chromatography (GC), liquid chromatography (LC) and ultraviolet-visible spectroscopy (UV-VIS) methods are considered. The respective advantages of each method are explained in detail. In addition, influencing factors for sorption in the first place are being discussed including particle size and shape (especially micro and nanoparticles) and the type of polymer, as well as methods for determining sorption kinetics. Since the particles are not present in the environment in a virgin state, the influence of aging on sorption is also considered.

scholarly journals Composition, Temperature and Frequency Dependent Magnetic, Dielectric and Electrical Properties of Magnesium-Zinc Ferrites

2012 ◽  
Vol 36 (2) ◽  
pp. 199-212 ◽  
Author(s):  
M Mahbubur Rahman ◽  
Md Shahin Sheak ◽  
Soheli Pervin ◽  
Nasir Uddin ◽  
Farid Ahmed ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Curie Temperature ◽  
Interfacial Polarization ◽  
Initial Permeability ◽  
Dielectric Behavior ◽  
Dielectric Dispersion ◽  
Cu Content ◽  
Virgin State ◽  
Academy Of Sciences ◽  
Magnetic Dielectric

Polycrystalline spinel MgxZn0.3Cu0.7-2xFe2+xO4, where x = 0.10, 0.20, 0.25, 0.30 and 0.35  ferrites (hereafter abbreviated as Mg-Zn) have been prepared by conventional double sintering technique. The samples were sintered at 1250°C in air for 6 hours. Measurements have been done at temperature and frequency ranges of 0 - 350°C and 0 - 500 kHz, respectively. In this work, some extrinsic magnetic properties such as Curie temperature, initial permeability, loss factor, quality factor, dielectric constant and resistivity of the samples have been studied. The Curie temperature and loss tangent of the samples decreased with increase in Cu-content whereas permeability, Qfactor, resistivity and dielectric constant have been noticed to be increased with the increase in Cucontent.  The decrease in Curie temperature related to fact of weakening the strength of exchange AB  interaction. Maxwell-Wagner type of interfacial polarization might have found correlated with  the normal dielectric behavior of the samples, however no relaxation peaks were observed in the  dielectric dispersion curves of the Mg-Zn samples in virgin state or doped state. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12963 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 199-212, 2012

Real-Time Monitoring of Acoustic Linear and Nonlinear Behavior of Titanium Alloys During Cyclic Loading

1999 ◽  
Vol 591 ◽  
Author(s):  
J. Frouin ◽  
J. Maurer ◽  
S. Sathish ◽  
D. Eylon ◽  
J.K. Na ◽  
...  
Keyword(s):  
Real Time ◽  
Low Cycle Fatigue ◽  
Nonlinear Behavior ◽  
Gradual Change ◽  
Electron Microscopic ◽  
Acoustic Nonlinearity ◽  
Test Conditions ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Virgin State

ABSTRACTVariation in acoustic nonlinearity has been monitored in real time during fatigue, on four dogbone specimens of Ti-6A1-4V, under low cycle fatigue conditions, from the virgin state all the way to fracture. The results of these experiments show that the acoustic nonlinearity undergoes large changes during the fatigue and follows a similar trend for the material under given fatigue test conditions. Transmission electron microscopic (TEM) examination of the samples with similar composition fatigued to different stages indicates a gradual change in the microstructure and dislocation density, which correlates with the changes in acoustic nonlinearity.

ABSENCE OF CO DISSOCIATION ON Mo(110): TPD AND DFT STUDY

2010 ◽  
Vol 17 (05n06) ◽  
pp. 469-475 ◽  
Author(s):  
N. V. PETROVA ◽  
V. D. OSOVSKII ◽  
D. YU BALAKIN ◽  
YU G. PTUSHINSKII ◽  
I. N. YAKOVKIN
Keyword(s):  
Dft Calculations ◽  
Density Functional ◽  
Co Adsorption ◽  
Temperature Programmed Desorption ◽  
Thermally Induced ◽  
First Order ◽  
Co Dissociation ◽  
Virgin State ◽  
Temperature Programmed ◽  
Good Agreement

The problem of the CO dissociation on Mo (110) has been addressed by means of temperature-programmed desorption (TPD) and density-functional (DFT) calculations. The TPD spectra show a first-order CO desorption, which indicates the desorption from a "virgin" state, not a recombinative form of desorption. The height of the potential barrier for the dissociation (2.75 eV), estimated from DFT calculations, substantially exceeds the energy of CO chemisorption (2.1 eV), which makes the thermally induced CO dissociation on Mo improbable. Monte Carlo simulations of TPD spectra, performed using estimated chemisorption energies, are in good agreement with experiment and demonstrate that the two-peak shape of the spectra can be explained without involving the CO dissociation. Thus, the results of the present study finally refute the concept of a dissociative form of CO adsorption on Mo surfaces.

Magnetic Structures of Holmium. I. The Virgin State

1966 ◽  
Vol 151 (2) ◽  
pp. 414-424 ◽  
Author(s):  
W. C. Koehler ◽  
J. W. Cable ◽  
M. K. Wilkinson ◽  
E. O. Wollan
Keyword(s):  
Magnetic Structures ◽  
Virgin State
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