INVESTIGATION OF THE SPECIFICITY OF ULTRASONIC TESTING OF CAST IRON WITH GLOBULAR GRAPHITE USING LONGITUDINAL ELASTIC WAVES

2020 ◽  
pp. 6-25 ◽  
Author(s):  
V. N. Danilov ◽  
L. V. Voronkova
Keyword(s):  
Cast Iron ◽  
Ultrasonic Testing ◽  
Rayleigh Scattering ◽  
Frequency Spectra ◽  
Longitudinal Waves ◽  
Globular Graphite ◽  
Useful Signal ◽  
Two Samples ◽  
Standard Normal ◽  
Experimental Values

On the basis of the previously developed model for estimating the attenuation coefficient of elastic longitudinal waves in cast iron due to their Rayleigh scattering on graphite inclusions, the influence of such attenuation for cast iron with globular graphite on the characteristics of signals with frequency spectra of different widths depending on the nominal pulse frequencies, cast iron models and the distance traveled by the ultrasonic wave is studied. Computer modeling acoustic channel for environment – cast iron with globular graphite for standard normal probes of two types for studying influence of such environment on characteristics real transmitting and registered signals at the ultrasonic testing. Comparison of results of calculations of spectrums and pulses of registered bottom signals with their experimental values for two samples of cast iron with globular graphite has shown an opportunity of use of the applied settlement model for description of the actual physical phenomena quite adequate for practice. Influence of attenuation of longitudinal waves in cast iron with globular graphite on the directivity characteristic of their radiation is shown on model of cast iron and duration of a pulse. The estimation of the relation of levels of a registered signal and structural noise for various reflectors and characteristics of controllable cast iron has shown performance of recommendations by I. N. Ermolov on reliable detection of a useful signal on a background of noise for thickness, before established experimentally. Features of DGS-diagrams for cast iron with globular graphite, caused by higher, than in steel, attenuation of longitudinal waves and a little smaller speeds of their distribution are marked.

INVESTIGATION OF THE POSSIBILITIES OF ULTRASONIC TESTING OF CAST IRON WITH LAMELLAR GRAPHITE USING STANDARD NORMAL PROBE

2020 ◽  
pp. 4-18 ◽  
Author(s):  
V. N. Danilov ◽  
L. V. Voronkova
Keyword(s):  
Cast Iron ◽  
Ultrasonic Testing ◽  
Signal To Noise Ratio ◽  
Calculation Model ◽  
Normal Probe ◽  
Two Samples ◽  
Standard Normal ◽  
Lamellar Graphite ◽  
Comparison Of The Results ◽  
Physical Phenomena

Computer simulation of acoustic paths for medium – cast iron with lamellar graphite for standard normal probe of several types was carried out in order to study the effect of such medium on the characteristics of transmitted and received signals during ultrasonic testing. In the course of studies to calculate the attenuation coefficient of longitudinal waves in cast iron with lamellar graphite, due to their Rayleigh and phase scattering by graphite inclusions, the previously developed model was used. Comparison of the results of calculations of spectra and pulses of the recorded signals for two samples of cast iron with lamellar graphite confirmed the possibility of using the developed calculation model for a description of real physical phenomena adequate for the practice of ultrasonic testing. The ratio of the recorded signal and structural noise levels for different models of transducers, reflectors and characteristics of the controlled cast iron is estimated. Shown that increased attenuation of the longitudinal wave in cast iron in comparison with steel as a result of scattering by inclusions leads to higher level of this noise and can greatly reduce the signal-to-noise ratio in the detection of the reflected from the defect signals.

SOME FEATURES OF ULTRASONIC TESTING OF CAST IRON OBJECTS WITH FLAKE AND GLOBULAR GRAPHITE USING NORMAL LINEAR PROBES WITH PHASED ARRAYS

2020 ◽  
pp. 4-19
Author(s):  
V. N. Danilov ◽  
L. V. Voronkova
Keyword(s):  
Cast Iron ◽  
Longitudinal Wave ◽  
Attenuation Coefficient ◽  
Computer Modelling ◽  
Signal Spectrum ◽  
Flake Graphite ◽  
Longitudinal Waves ◽  
Globular Graphite ◽  
The Difference ◽  
Directivity Characteristics

Computer modelling of the acoustic characteristics of signals of direct normal probe with phased array (PFR) in the cast iron with flake and globular graphite was performed. As a result the form of acoustic pulses of a longitudinal wave, depending on the passed by wave distance and the values of attenuation coefficient for different models of cast iron was calculated. The main modeled characteristics of the probe include the directivity characteristic and the change in the amplitude of the signal along the acoustic axis. It is shown that the difference in the PFR directivity characteristics for cast iron with flake graphite of different models and steel is due to two factors – significantly lower longitudinal wave velocities in cast iron compared to steel and a decrease in its operating frequency due to attenuation. In this case, for cast iron with globular graphite, a small change in the width of the diagrams is due only to the lower speed of longitudinal waves in cast iron compared to steel. For cast iron with flake graphite model 3, the phenomenon of nonlinear attenuation due to a decrease in the frequency of the maximum of the signal spectrum during the propagation of a longitudinal wave in cast iron with a corresponding decrease in the frequency – dependent attenuation coefficient is established. Evaluation of the nonlinearity of attenuation for cast iron with globular graphite showed that it is very small. The influence of calculation of initial signal delays on the velocity of longitudinal waves in steel on the directivity characteristics in cast iron, decreasing with increasing focus distance, is established. It is shown that for cast iron with flake graphite there are cases when the direction of transmitting of PFR in cast iron is practically absent.

scholarly journals The Effect of Magnitude and Direction of Heat Flow on the Thermal Conductivity for Insulation Materials (Glass Wool) by Using Probe Method

2018 ◽  
Vol 7 (4.20) ◽  
pp. 536
Author(s):  
Hussein Humaish ◽  
. .
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Industrial Process ◽  
Glass Wool ◽  
Probe Method ◽  
Heat Power ◽  
Insulation Materials ◽  
Two Samples ◽  
Hot Disk ◽  
Experimental Values

The thermal energy of building is determined by the thermal properties of the materials and how to install these materials in the elements of buildings according to the direction of heat transfer. The effectiveness of thermal insulation (glass wool) is dependent on its thermal conductivity which is varies in different directions of fibers of glass wool. Glass wool is formed of fibers and binders tangled together during the industrial process to provide some elasticity. The experimental values of thermal conductivity of the insulation materials are changed according to magnitude of the heat power and direction of fiber arrangement. The thermal conductivity for insulation materials has been measured by using probe method,  Huekseflux ® TP02 used to measure the thermal conductivity by emit the flow perpendicular and parallel to the fibers of glass wool. Two samples of yellow glass wool (density 68 kg/m3) with dimensions (10 ×10 ×30) cm have been used. Hot Disk bulk isotropic module has been used to evaluate thermal conductivity. TPS source (Hot Disk probe reference: 4922) characterized by a diameter of 14.61 mm has been selected. COMSOL® multiphysics axisymmetric 2D model has been used to follow the axial and the radial directions of the heat transfer. 

Fatigue Behaviour of Cast Iron with Globular Graphite

2004 ◽  
Vol 6 (7) ◽  
pp. 541-544 ◽  
Author(s):  
P. Hübner ◽  
G. Pusch ◽  
L. Krodel
Keyword(s):  
Cast Iron ◽  
Fatigue Behaviour ◽  
Globular Graphite

Tribological Research of Properties of Heat – Treated Cast Irons with Globular Graphite

2015 ◽  
Vol 818 ◽  
pp. 209-212 ◽  
Author(s):  
Jozef Bronček ◽  
Peter Fabian ◽  
Norbert Radek
Keyword(s):  
Cast Iron ◽  
Metal Matrix ◽  
Mechanical Energy ◽  
Basic Metal ◽  
Cast Irons ◽  
Globular Graphite ◽  
Treated Steel ◽  
Heat Treated ◽  
Properties Of Materials ◽  
Heat Treated Steel

The contribution deals with the evaluation of tribological properties of materials: isothermally heat-treated cast iron ADI, heat-treated cast iron with globular graphite HTDI with sorbitic structure of the basic metal matrix and heat-treated steel C45. The aim of the research is to gain another knowledge for the application of materials in the condition where the loss of mechanical energy and the loss of material caused by parts wear are being appeared.

Дифференциальный фон электрического сигнала, снимаемого с индукционной магнитной головки

2021 ◽  
pp. 51-61
Author(s):  
В.В. Павлюченко ◽  
Е.С. Дорошевич
Keyword(s):  
Inhomogeneous Magnetic Field ◽  
Measuring System ◽  
Local Source ◽  
Electric Signal ◽  
Natural Oscillations ◽  
Electric Voltage ◽  
Frequency Spectra ◽  
Useful Signal ◽  
Sufficient Magnitude ◽  
Local Defects

Experimental dependences U(t) of the electric voltage taken from an induction magnetic head (MH) moving relative to a magnetic carrier (MH) are presented. The backgrounds of the edges of the MN, local defects of the MN, the background of the inhomogeneous magnetic field of the local source, the backgrounds of defects and structural inhomogeneities of the object, the etheric electromagnetic background, the background of the quality of the surface of the object and surface microscopic inhomogeneities of the material have been identified and investigated. The resonant backgrounds of self-excitation of the measuring system on the signals of the edges of the MN, defects of the MN, instrument and network pickups and interference, object defects, and etheric electromagnetic fields are revealed and investigated. Resonance peaks are the result of self-excitation of the measuring system, which includes the MG, and arise on the trailing edges of any signals of sufficient magnitude, the duration of the trailing edge of which is about a quarter of the period of natural oscillations of the measuring system. The amplitude and frequency spectra of the background signals of object defects, MI and noise and the analytical expressions describing them are determined. The results of the extraction of the useful signal from the complete signal recorded on the MN are shown. Investigations of the differential background of an electric signal allow, together with the previously developed methods of hysteresis interference, to control the properties of objects in an automatic mode with program control, which significantly increases the sensitivity and accuracy of control. To achieve this goal, it is recommended to set the parameters of the measurement system at the threshold of the onset of natural free oscillations in it.

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