Параметры акустической неоднородности для неразрушающей оценки влияния технологии изготовления и эксплуатационной поврежденности на структуру металла

2020 ◽  
pp. 24-36
Author(s):  
Л.А. Пасманик ◽  
А.В. Камышев ◽  
А.В. Радостин ◽  
В.Ю. Зайцев
Keyword(s):  
Acoustic Method ◽  
Physical Parameters ◽  
Acoustic Parameters ◽  
Ultrasound Waves ◽  
Microstructural Alterations ◽  
The Difference ◽  
Manufacturing Technologies ◽  
Metal Microstructure ◽  
Non Destructive ◽  
Baseline State

In this paper, we propose a non-destructive acoustic method for assessing microstructural alterations produced in metals as a result of processing and exploitation damage. The method is based on measuring ratios of longitudinal and shear ultrasound waves velocities with subsequent normalization of these ratios to their counterparts corresponding to a “baseline state” of the metal. The choice of the baseline state depends of the particular problem and corresponds to either the pre-exploitation metal state for the object to be monitored, or the state of reference samples, for which the strength characteristics fall into acceptable range according to the results of conventional strength-evaluation methods. For the introduced Microstructure-Sensitive Acoustic parameters (MSA-parameters) characterizing alterations in the metal microstructure, we discuss the reasons of the difference between the baseline and current states of the metal in terms of the total values of the normal and tangential compliances imparted to the metal due to the appearance of microstructural heterogeneities. The efficiency of utilization of the proposed acoustic diagnostic parameters is demonstrated using experimental data for two types of metal samples with essentially different microstructure (isotropic and anisotropic heterogeneity). Measurements of the proposed microstructure-sensitive acoustic parameters can be used in a variety of applications: (i) non-destructive quality control of manufacturing technologies in metallurgy and mechanical engineering (ii) evaluation of damage accumulation during exploitation manufactured constructions/samples; (iii) evaluation of mechanical properties, fracture resistance and other physical parameters of metals.

scholarly journals Nonlinear stability of two-layer shallow water flows with a free surface

2020 ◽  
Vol 476 (2236) ◽  
pp. 20190594
Author(s):  
Francisco de Melo Viríssimo ◽  
Paul A. Milewski
Keyword(s):  
Free Surface ◽  
Initial Data ◽  
Nonlinear Stability ◽  
Mathematical Proof ◽  
Passive Layer ◽  
Physical Parameters ◽  
Immiscible Fluid ◽  
Dimensional System ◽  
The Cauchy Problem ◽  
The Difference

The problem of two layers of immiscible fluid, bordered above by an unbounded layer of passive fluid and below by a flat bed, is formulated and discussed. The resulting equations are given by a first-order, four-dimensional system of PDEs of mixed-type. The relevant physical parameters in the problem are presented and used to write the equations in a non-dimensional form. The conservation laws for the problem, which are known to be only six, are explicitly written and discussed in both non-Boussinesq and Boussinesq cases. Both dynamics and nonlinear stability of the Cauchy problem are discussed, with focus on the case where the upper unbounded passive layer has zero density, also called the free surface case. We prove that the stability of a solution depends only on two ‘baroclinic’ parameters (the shear and the difference of layer thickness, the former being the most important one) and give a precise criterion for the system to be well-posed. It is also numerically shown that the system is nonlinearly unstable, as hyperbolic initial data evolves into the elliptic region before the formation of shocks. We also discuss the use of simple waves as a tool to bound solutions and preventing a hyperbolic initial data to become elliptic and use this idea to give a mathematical proof for the nonlinear instability.

scholarly journals Acoustic Characterization of Some Steel Industry Waste Materials

2021 ◽  
Vol 11 (13) ◽  
pp. 5924
Author(s):  
Elisa Levi ◽  
Simona Sgarbi ◽  
Edoardo Alessio Piana
Keyword(s):  
Thermal Characteristic ◽  
Environmental Benefits ◽  
Acoustic Properties ◽  
Physical Parameters ◽  
Industry Waste ◽  
Acoustic Characterization ◽  
Minimization Procedure ◽  
The Difference ◽  
By Products

From a circular economy perspective, the acoustic characterization of steelwork by-products is a topic worth investigating, especially because little or no literature can be found on this subject. The possibility to reuse and add value to a large amount of this kind of waste material can lead to significant economic and environmental benefits. Once properly analyzed and optimized, these by-products can become a valuable alternative to conventional materials for noise control applications. The main acoustic properties of these materials can be investigated by means of a four-microphone impedance tube. Through an inverse technique, it is then possible to derive some non-acoustic properties of interest, useful to physically characterize the structure of the materials. The inverse method adopted in this paper is founded on the Johnson–Champoux–Allard model and uses a standard minimization procedure based on the difference between the sound absorption coefficients obtained experimentally and predicted by the Johnson–Champoux–Allard model. The results obtained are consistent with other literature data for similar materials. The knowledge of the physical parameters retrieved applying this technique (porosity, airflow resistivity, tortuosity, viscous and thermal characteristic length) is fundamental for the acoustic optimization of the porous materials in the case of future applications.

Non-Destructive Measurements of III-V Semiconductor Device Structure by a Hard X-ray Microprobe

1991 ◽  
Vol 240 ◽  
Author(s):  
F. Uchida ◽  
J. Shigeta ◽  
Y. SUZUKI
Keyword(s):  
Semiconductor Device ◽  
Film Structure ◽  
Device Structure ◽  
X Ray ◽  
Model Sample ◽  
Device Structures ◽  
The Difference ◽  
X Ray Absorption ◽  
Non Destructive ◽  
Non Destructive Characterization

ABSTRACTA non-destructive characterization technique featuring a hard X-ray Microprobe is demonstrated for lll-V semiconductor device structures. A GaAs FET with a 2 μm gate length is measured as a model sample of a thin film structure. X-ray scanning microscopic images of the FET are obtained by diffracted X-ray and fluorescence X-ray detection. Diffracted X-ray detection measures the difference in gate material and source or drain material as a gray level difference on the image due to the X-ray absorption ratio. Ni Ka fluorescence detection, on the other hand, provides imaging of 500 Å thick Ni layers, which are contained only in the source and drain metals, through non-destructive observation.

Analytical Limit Load Procedure for The Axial Complex Shaped Defect in a Pressurized Pipe

2021 ◽  
Author(s):  
Igor Orynyak ◽  
Julia Bai ◽  
Roman Mazuryk
Keyword(s):  
General Procedure ◽  
Limit Load ◽  
Admissible Solution ◽  
Experimental Comparison ◽  
Physical Parameters ◽  
Equilibrium Equations ◽  
Axial Complex ◽  
The Difference ◽  
Full Scale Tests ◽  
Distribution Of Stress

Abstract The paper is devoted to elaboration of the analytical O-procedure for limit load analysis of complex shaped axial defect in a pressurized pipe. It is based on the classical lower bound theorem of the theory of plasticity, and consists in construction of the statically admissible solution, where distribution of stress satisfies to the equilibrium equations and strength conditions. O-procedure is an optimization process to get the most favorable stress distribution for providing the maximal pressure. It allows to explicitly account for the variable geometrical and physical parameters. Contrary to other approaches, the derived formula for rectangular defect is only a particular case of the general procedure application. Four different methods for the complex defects are compared. They are: first, ASME, A-, rectangular defect formula combined with RSTRENG, R-, procedure, i.e., A-R approach; second, PCORRC, P-, formula with R-procedure, P-R approach; third, Orynyak's, O-, formula with R-procedure, O-R approach; and fourth, our universal O-procedure. The verification begins for rectangular defects where both theoretical and experimental comparison is performed for A-, P-, and O- formulas. The difference between them is small, provided that all three employ the same characteristic of material, here the ultimate strength. Then theoretical comparison for A-R, P-R, O-R approaches and O-procedure is performed for the artificial complex defects, for two symmetrical rectangular defects, for triangular defect. Experimental comparison between four methods is made based on the well-known University of Waterloo full scale tests.

scholarly journals Research on the Difference of Physical Parameters of Concrete in Saline-alkali Environment

2020 ◽  
Vol 143 ◽  
pp. 01014
Author(s):  
Yumao Qi ◽  
Junge Huang ◽  
Yu Liu ◽  
Jian Pei
Keyword(s):  
Reinforced Concrete ◽  
Sodium Sulfate ◽  
Rock Specimen ◽  
Test Block ◽  
Control Group ◽  
Physical Parameters ◽  
Significant Difference ◽  
Specimen Test ◽  
Water Test ◽  
The Difference

In order to better study the corrosion of concrete in saline-alkali area, the model tests of concrete and reinforced concrete with different ions and different ion concentrations were constructed. Taking the test blocks mixed with water as the control group, the resistance and polarizability of the test block during the maintenance period were measured by rock specimen tester and rock specimen test frame. The one-way variance analysis of the measured values of each test block was carried out by spss software, investigating the difference of electrical parameters of each concrete. The results show that there is significant difference in the resistance between the clear water concrete test block and the 3% sodium sulfate concrete test block at the level of significance ≤ 0.05. For reinforced concrete test blocks, the resistivity difference between water test block and 3% sodium sulfate test block and 6% sodium sulfate test block is not significant, and the resistivity difference between water test block and 15% sodium sulfate test block and 3% sodium chloride test block is significant. No matter concrete or reinforced concrete, the polarizability of test blocks mixed with water and test blocks mixed with each solution is significantly different. Therefore, the polarizability parameters can be used to distinguish whether the concrete is corroded by salt and alkali. It is feasible to use polarizability parameter to detect concrete erosion by salt and alkali.

scholarly journals Detection of Internal Holes in Additive Manufactured Ti-6Al-4V Part Using Laser Ultrasonic Testing

2020 ◽  
Vol 10 (1) ◽  
pp. 365 ◽  
Author(s):  
Jie Yu ◽  
Dongqi Zhang ◽  
Hui Li ◽  
Changhui Song ◽  
Xin Zhou ◽  
...  
Keyword(s):  
Ultrasonic Testing ◽  
Laser Doppler Vibrometer ◽  
Laser Ultrasonic ◽  
Ultrasound Waves ◽  
Hole Defect ◽  
X Ray Computed ◽  
Hole Defects ◽  
Pulse Echo ◽  
The Relationship ◽  
Non Destructive

For a non-contact, non-destructive quality evaluation, laser ultrasonic testing (LUT) has received increasing attention in complex manufacturing processes, such as additive manufacturing (AM). This work assessed the LUT method for the inspection of internal hole defects in additive manufactured Ti-6Al-4V part. A Q-switched pulsed laser was utilized to generate ultrasound waves on the top surface of a Ti-6Al-4V alloy part, and a laser Doppler vibrometer (LDV) was utilized to detect the ultrasound waves. Sub-millimeter (0.8 mm diameter) internal hole defect was successfully detected by using the established LUT system in pulse-echo mode. The method achieved a relatively high resolution, suggesting significant application prospects in the non-destructive evaluation of AM part. The relationship between the diameter of the hole defects and the amplitude of the laser-generated Rayleigh waves was studied. X-ray computed tomography (XCT) was conducted to validate the results obtained from the LUT system.

scholarly journals Tool Wear Assessment Approach Based on the Neighborhood Rough Set Model and Nearest Neighbor Model

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ren Sheng ◽  
Xiaoran Zhu
Keyword(s):  
Rough Set ◽  
Nearest Neighbor ◽  
Milling Process ◽  
Two Dimension ◽  
Assessment Approach ◽  
Intersection Area ◽  
Neighborhood Rough Set ◽  
The Difference ◽  
Boundary Curves ◽  
Baseline State

In order to assess the degree of wear of tool for milling process quantitatively, a new assessment approach is proposed. Firstly, making full use of the neighbor information, two sensitive features are selected by using the neighborhood rough set model, and then, boundary curves are established by using the nearest neighbor model with noncounter data in two dimension spaces. Secondly, the intersection area or expanding area is used to describe the difference between two boundary models because the intersection area or expanding area can consider the effect of distance and angle simultaneously in two dimension spaces. Thirdly, after determining a baseline state, a new quantitative assessment indicator (QAI) can be calculated based on the intersection area or expanding area. The QAI can directly measure the difference between the model of baseline state and the model of unknown state and indirectly measure the degree of wear of tool. Finally, the effectiveness of the assessment approach is proven by using the Milling Dataset which was provided by the NASA Ames Research Center.

scholarly journals Physical parameters and chemical abundances of Planetary Nebulae in the large Magellanic Cloud

1997 ◽  
Vol 180 ◽  
pp. 471-471 ◽  
Author(s):  
R. E. Carlos Reyes ◽  
J. E. Steiner ◽  
F. Elizalde
Keyword(s):  
Planetary Nebulae ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Physical Parameters ◽  
Chemical Abundances ◽  
The Difference

In the present work we have computed the physical parameters and chemical abundances for 45 planetary nebulae (PN) in the Large Magellanic Cloud (LMC) using the photoionization code CLOUDY, developed by Ferland (1993). CLOUDY is used as a subroutine in the code DIANA, developed by Elizalde & Steiner (1996), which minimises indices that measures the difference between the calculated and real nebula.

scholarly journals Variations of the snow physical parameters and their effects on albedo in Sapporo, Japan

2007 ◽  
Vol 46 ◽  
pp. 375-381 ◽  
Author(s):  
Teruo Aoki ◽  
Hiroki Motoyoshi ◽  
Yuji Kodama ◽  
Teppei J. Yasunari ◽  
Konosuke Sugiura
Keyword(s):  
Grain Size ◽  
Near Infrared ◽  
Mineral Dust ◽  
Radiation Budget ◽  
Radiative Transfer Model ◽  
Physical Parameters ◽  
Transfer Model ◽  
Infrared Wavelengths ◽  
The Difference ◽  
Impurity Models

AbstractContinuous measurements of the radiation budget and meteorological components, along with frequent snow-pit work, were performed in Sapporo, Hokkaido, Japan, during two winters from 2003 to 2005. The measured relationships between broadband albedos and the mass concentration of snow impurities were compared with theoretically predicted relationships calculated using a radiative transfer model for the atmosphere–snow system in which different types (in light absorption) of impurity models based on mineral dust and soot were assumed. The result suggests that the snow in Sapporo was contaminated not only with mineral dust but also with more absorptive soot. A comparison of the measured relationships between broadband albedos and snow grain size for two different layers with the theoretically predicted relationships revealed that the visible albedo contains information about the snow grain size in deeper snow layers (10 cm), and the near-infrared albedo contains only surface information. This is due to the difference in penetration depth of solar radiation into snow between the visible and the near-infrared wavelengths.

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