CALCULATION METHOD OF IMPEDANCE MODULE FOR CORROSION MONITORING  OF SURFACE STATE OF CHROMONICKEL STEELS

In discussed issue the additional criterion for chromium-nickel steels surface state assessment is proposed. It is used in periodic potentiostatic regime of stainless steels surface state monitoring under the condition of pitting corrosion origin. Electrochemical investigations were carried out with pitting corrosion resistant austenitic (12Х18Н10Т) and austenitic-ferritic chromium-nickel steels 10Х17Н13М2Т in chloride solutions of 0.1 mol/L NaCl and 0.5 mol/l NaCl with the additional oxidant K2Cr2O7. Polarization curves were recorded under potentiostatic mode of polarization in the electrochemical three-electrode cell using the ZIVE SP2 workstation and a personal computer. The fast Fourier transformation method was used for conducting the spectral analysis, as this method is more effective in terms of the algorithmic complexity when processing a large amount of the initial data. It is established that scalar impedance angular coefficient shows the current oscillation frequencies change concerned with the pitting occurrence and passivation process. The scalar impedance angular coefficient allows to estimate the pitting corrosion evaluation processes boundaries: passivity; metal dissolution due to the development of metastable pittings; the metastable nucleation and passivation processes concurred with the stable pitting development. The algorithm based on the statistical method of spectral analyses for scalar impedance angular coefficient calculation is developed. It is established that the decrease in passive film total resistance corresponds to the breakdown process and first metastable, and then stable local surface destructions that reflect on the higher the scalar impedance angular coefficient value. The boundary values of an additional criterion for surface state assessment were proposed, on the basis of which an interval scale was constructed to determine the current state of the surface of chromium-nickel steels. It is shown that the boundary values of the scalar impedance angular coefficient correspond to the metallographic studies of investigated steels.

Download Full-text

An Integrated Architecture for Corrosion Monitoring and Testing, Data mining, Modeling and Diagnostics/Prognostics

International Journal of Prognostics and Health Management ◽

10.36001/ijphm.2017.v8i1.2531 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Honglei Li ◽

Margaret R Garvan ◽

Jiaming Li ◽

Javier Echauz ◽

George J. Vachtsevanos ◽

...

Keyword(s):

Data Mining ◽

Image Processing ◽

Pitting Corrosion ◽

Particle Filtering ◽

Propagation Model ◽

Corrosion Monitoring ◽

Modeling Framework ◽

Process Detection ◽

The Impact ◽

Detection And Quantification

It has been established that corrosion is one of the most important factors causing deterioration and decreased performance and reliability in critical aerospace and industrial systems. Corrosion monitoring, detection, and quantification are recognized as key enabling technologies to reduce the impact of corrosion on the integrity of aircraft and industrial assets. Accurate and reliable detection of corrosion initiation and propagation, with specified false alarm rates, requires novel tools and methods, including verifiable simulation and modeling methods. This paper reports an experimental investigation of the detection and quantification of pitting corrosion on aluminum alloy panels using 3D surface metrology methods and image processing techniques. Panel surfaces were evaluated by laser microscopy and stylus-based profilometry to characterize global and local surface features. Promising imaging and texture features were extracted and compared between coated and uncoated aluminum panels at different exposure times under accelerated corrosion conditions. Image processing, information processing, and data mining techniques were utilized to evaluate the presence and extent of pitting corrosion. A new modeling framework for corrosion stages is introduced that emphasizes the representation of pitting corrosion and ultimately the crack formation process. Detection and prediction of the evolution of corrosion stages relies on data, a particle filtering method, and the corrosion propagation model. Results from these experimental studies demonstrate the efficacy of this proposed methodology.

Download Full-text

Acoustic waves in two-fraction mixtures of liquid with vapor-gas bubbles

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2012.1.011 ◽

2012 ◽

Vol 9 (1) ◽

pp. 65-68

Author(s):

R.N. Gafiyatov

Keyword(s):

Acoustic Waves ◽

Gas Bubbles ◽

Transformation Method ◽

Fast Fourier Transformation ◽

Fourier Transformation Method ◽

Impulse Pressure ◽

Pressure Perturbations ◽

The Mathematical Model ◽

Different Gases ◽

Fractional Mixture

The mathematical model of two-fractional mixture of liquid with vapor-gas bubbles of different gases and sizes with phase transformations is presented. The dispersive equation is received, dispersive curves that determine the propagation of acoustic disturbances was plotted. Calculations on the propagation of impulse pressure perturbations were performed by means of a fast Fourier transformation method.

Download Full-text

A small box Fast Fourier Transformation method for fast Poisson solutions in large systems

Computer Physics Communications ◽

10.1016/j.cpc.2013.07.010 ◽

2013 ◽

Vol 184 (12) ◽

pp. 2693-2702 ◽

Cited By ~ 1

Author(s):

Xiang-Wei Jiang ◽

Shu-Shen Li ◽

Lin-Wang Wang

Keyword(s):

Fourier Transformation ◽

Transformation Method ◽

Fast Fourier Transformation ◽

Large Systems ◽

Fourier Transformation Method ◽

Fast Fourier Transformation Method

Download Full-text

Fast Fourier Transformation method for computing the permeability of periodic porous media

Vietnam Journal of Mechanics ◽

10.15625/0866-7136/8444 ◽

2017 ◽

Vol 39 (2) ◽

pp. 121-133

Author(s):

Nguyen Trung Kien ◽

Nguyen Duy Hung

Keyword(s):

Porous Media ◽

Fourier Transformation ◽

Linear Problem ◽

Stokes Equations ◽

Solid Phase ◽

Transformation Method ◽

Fast Fourier Transformation ◽

Fourier Space ◽

Fourier Transformation Method ◽

Rigid Skeleton

A Fourier-based method is adopted to determine the permeability of periodic porous media made up of a rigid skeleton saturated by viscous fluid. The flow, induced by a prescribed macroscopic gradient of pressure, adopts the Stokes equations with incorporating a condition of adherence at the surface of the solid. The permeability is determined by solving a linear problem on a unit cell for which we determine the local velocity fields due to a prescribed gradient of pressure. The method uses the Fourier Transformation and exact expressions of the periodic Green tensor in the Fourier space. It is shown that the resolution of the problem requires an introducing of undetermined forces acting within the solid phase.

Download Full-text

FFT simulations and multi-coated inclusion model for macroscopic conductivity of 2D suspensions of compound inclusions

Vietnam Journal of Mechanics ◽

10.15625/0866-7136/37/3/5096 ◽

2015 ◽

Vol 37 (3) ◽

pp. 169-176

Author(s):

Nguyen Van Luat ◽

Nguyen Trung Kien

Keyword(s):

Approximation Method ◽

Fourier Transformation ◽

Dimensional Space ◽

Transformation Method ◽

Fast Fourier Transformation ◽

Two Dimensional ◽

Random Models ◽

Coated Inclusion ◽

Fourier Transformation Method ◽

Fast Fourier Transformation Method

Article introduces the Fast-Fourier transformation method (FFT) and an approximation method to calculate the conductivity of compound-inclusion composites in two-dimensional space. The approximation compares favorably with the numerical results for a number of periodic and random models over a range of volume proportions of phases, but divers at large volume proportions of the included phases when the interactions between the inclusions are more pronounced.

Download Full-text

Potential of Workshop Measurement Positioning System to Measure Oscillation Frequencies of Rigid Structures

Applied Sciences ◽

10.3390/app9030595 ◽

2019 ◽

Vol 9 (3) ◽

pp. 595 ◽

Cited By ~ 2

Author(s):

Chunbao Xiong ◽

Hongzhi Bai ◽

Jiarui Lin

Keyword(s):

Three Dimensional ◽

Transformation Method ◽

Fast Fourier Transformation ◽

Positioning System ◽

Test Bed ◽

Coordinate Measurement ◽

Intrinsic Parameters ◽

High Measurement ◽

Fourier Transformation Method ◽

Oscillation Frequencies

A workshop measuring and positioning system (wMPS) is a large three-dimensional (3D) coordinate-measurement system based on optoelectronic scanning. It is capable of large-range coverage, high measurement accuracy and frequency, and multi-task synchronous measurement. Existing geodetic instruments cannot measure the intrinsic parameters of strong rigid structures. Thus, this study conducted experiments to explore the feasibility of the wMPS to measure the intrinsic parameters of rigid structures. A test bed was established using a reverse-engineering method to simulate the oscillation frequency of the structure. Displacement data, which changed with the time series through the fast Fourier transformation method, were analyzed to determine the feasibility and range of the wMPS in measuring intrinsic parameters of the structure. The experimental results demonstrated that the wMPS can measure the vibrational frequency up to 9 Hz with a 3-mm amplitude and up to 4 Hz with a 30-mm amplitude.

Download Full-text