Method for low-temperature local object loading in acoustic-emission nondestructive testing method

FIELD: physics.

SUBSTANCE: local stress-strain state is created in the construction by cooling the surface of the controlled area. Low-temperature energy is locally fed to the surface of the controlled area, received under the influence of the solid carbon dioxide CO2 "Dry ice" on the local control area. The appearance of the temperature gradient in the test material area is the cause of its stress-strain state, as a result of the dislocation motion, which will be accompanied by the acoustic-emission signals. The coordinates of the detected defects are determined and the hazard criteria of the detected defects is estimated by measuring the energy of the acoustic-emission signals initiated by the dislocation motion.

EFFECT: encreasing the reliability of defect detecting and performance of non-destructive testing in the acoustic-emission method of diagnosis.

3 dwg

 



 

Same patents:

FIELD: physics.

SUBSTANCE: in compliance with proposed method, the material specimen if loaded with the help of hydraulic press to register the acoustic signal emission. Said specimen is subjected to pulse effects to produce a longitudinal elastic wave. The latter stimulates a massive synchronous escape of dislocations from material crystal to get a total signal of acoustic emission recorded by piezo-transducer in a stable way.

EFFECT: simplified registration and processing of acoustic emission signal.

2 dwg

FIELD: oil and gas industry.

SUBSTANCE: method includes measurement of indicator diagram of well flow rate dependency on pressure drawdown and determination of the dependency peak corresponding to optimal pressure drawdown. Elastic strain dependency is measured, for example, propagation rate of elastic rate from porosity pressure in a core sample selected from the formation and placed into the hydraulic chamber with uniform pressure corresponding to conditions of natural occurrence, then porosity pressure is reduced smoothly up to the formation pressure with rate that does not exceed relaxation rate of limit strain in the core, which is used for assessment of acoustic emission non-availability, and then porosity pressure is continued to reduce as the core drawdown, and against commencement of sharp change in this dependency gradient reduction when plasticity limit is reached and acoustic emission occurs the limit value of optimal pressure drawdown is assessed.

EFFECT: improving accuracy in determination of optimal pressure drawdown.

1 dwg

FIELD: physics, acoustics.

SUBSTANCE: invention can be used for acoustic emission diagnosis of off-shore sleet-proof structures. The method comprises installing acoustic emission transducers of the audio range in critical structural components of a structure; detecting acoustic emission signals and determining the extent of the defect of the structure from parameters of the acoustic emission signals; wherein the method further includes installing in the critical structural components of the structure a group of accelerometers which detect mechanical stress of low-frequency vibrations in the infra-sound range, and then calculating a first cross-correlation function between signals coming from the acoustic emission transducers and the accelerometers, and then a second cross-correlation function between signals coming from each pair of nearest acoustic emission transducers, wherein defects of the structure are identified from the amplitude and shape of maxima of each correlation function, and coordinates of the defects are determined from the time delay of the maximum of the second correlation function between each pair of acoustic emission transducers.

EFFECT: high reliability of detection and diagnosis of hidden defects of offshore sleet-proof structures.

2 cl, 1 dwg

FIELD: testing equipment.

SUBSTANCE: use: for diagnostics and non-destructive check of metal structures. The substance of the invention consists in the fact that parameters of acoustic emission signals are received, recorded and assessed at the moment of structure loading, acoustic signals are digitised, they are preliminarily processed, noise is filtered, at the same time they first establish critical values of the load Pcr and regression coefficient krc, which characterises variation of the number of acoustic emission signals to variation of the load for a non-defect structure, then the structure is loaded to the value of the load exceeding the working load by (5…10)%, at the same time they record the number of signals and the load of the linear section of stationary acoustic emission, at the same time they record the regression coefficient k0, afterwards the structure is loaded by cyclic load, the amplitude value of which is exceeded gradually by (2…5)%, and whenever exceeding reaches (15…20)% above the working load, loading is stopped, if in the process of control k0<krc, then the structure is considered to be free of defects, and if the value k0>krc the structure is rejected.

EFFECT: improved validity of acoustic-emission control of metal structures.

3 cl, 4 dwg, 4 tbl

FIELD: transport.

SUBSTANCE: signals from acoustic emission transducers are received, recorded and processed in rolling run on rail. Note here that artificial irregularities in vertical plane are created at preset length of railway track. Acoustic emission transducers are arranged at said irregularities. Signals of said transducers allow making the decision about crack availability in rolling stock bogie running gear.

EFFECT: efficient diagnostics without special extra hardware.

2 dwg

FIELD: metallurgy.

SUBSTANCE: weld joint is subject to thermal action; acoustic emission signals are recorded, and the quality of the weld joint is evaluated as per their parameters. The acoustic emission signals are initiated by a local thermal action in turn at control points located in a line perpendicular to a weld; relationship of parameters of these signals is built for each control point from its distance to the weld, and the size of a heat-affected zone is evaluated as per the specified relationship as the distance between the control points that are maximum remote from the weld, at which the value of total energy of the acoustic signals is lower than in the parent (not subjected to thermal effect during welding) metal of the weld joint.

EFFECT: providing a possibility of evaluation of sizes of a heat-effected zone and control of a structural state of metal in this zone of weld joints.

1 dwg

FIELD: mining.

SUBSTANCE: invention relates to mining and is designed to determine the change in the stress state of the rock mass. The method comprises placement in the well of the hollow cylindrical acoustic line, receiving and analysis of parameters of ultrasonic signals propagating in it by means of the acoustic emission transducers mounted on its end surfaces. Preliminarily on the acoustic line coaxially with it and at some distance from each other at least two rings of textolite are fixed, which inner diameter coincides with the diameter of the acoustic line, and the outer - with the well diameter. Deformation of the well due to the shift of the reference pressure zone, results in deformation of the respective textolite rings and, respectively, the growth of acoustic-emission activity in these discs. The difference in time of arrival to the receiving transducers of those acoustic emission signals is measured, the amplitude of which is maximum of all incoming signals, and the depth of the zone of the reference pressure and its change in time is judged by the above mentioned time difference, the known length of the acoustic line and the measured rate of propagation of ultrasound in it.

EFFECT: increase in duration of the definition of changes in the stress state of rock mass in the vicinity of working during continuous monitoring acoustic-emission measurements of movement deeper into the solid mass of the zone of reference pressure.

4 dwg

FIELD: instrument making.

SUBSTANCE: invention can be used for acoustic emission control over rail weld quality. This invention consists in welding the butt, cutting of flash, registration of acoustic emission signals at weld cooling, measurement of acoustic emission signal count rate and division of control time into intervals. In case acoustic emission signal count rate is larger than threshold magnitude in at least one interval, weld quality is evaluated, Note here that, additionally, median of acoustic emission signal power is defined, threshold magnitudes are set by mean count rates and median of localised acoustic emission signal in two equal time intervals at weld cooling. In case count rate and signal power medians exceed their threshold magnitudes at whatever time intervals, welds are rejected.

EFFECT: higher validity of weld quality control.

2 cl, 2 dwg

FIELD: metallurgy.

SUBSTANCE: acoustic emission transducers are fitted at cold slab surface in the order that allows the control over the entire material of slab. Slab is mechanically strained by slab natural weight to 20-80% of slab material yield point. Strained slab is kept under stress for at least one minute to register acoustic emission signals for their processing. Acoustic emission source coordinates are determined to define the possibility of further use of the slab for production of hot-rolled strip by comparison of diagnostics parameter WAE with tolerable diagnostics parameter magnitude [WAE]. At WAE >[WAE] slab is considered unfit for further rolling.

EFFECT: comprehensive and accurate control.

1 dwg

FIELD: metallurgy.

SUBSTANCE: tested resilient element is strained several times to maximum deformation with registration of acoustic emission signals at every straining. Note here that tested element is strained two times and for short term by reduction while acoustic emission signals are registered continuously during second straining to define total quantity of pulses of total acoustic emission N2. Resilient element titanium alloy microstructure is evaluated by nine-point scale of grain size divided into three sets of point 4-5, 6-7 and 7-8 each corresponding to s separate range of the number of pulses of total acoustic emission A1, A2, A3. Microstructure quality are defined by pints of said scale from the following relationship: N2≤A1, or N2≤A2, or N2≤A3.

EFFECT: fast and simplified process for control over plate spring heat treatment conditions.

12 dwg, 3 tbl

FIELD: acoustic control methods.

SUBSTANCE: method includes measuring parameters of acoustic emission of control samples from examined metal during loading thereof. Control samples are subjected to prior one-axis load, following heating to 600°C, during which parameters of acoustic emission are measured: pulse count speed , pulse/sec, energy collection speed , mW2/sec and signals length collection speed , ms/sec, and relation of these from temperature is built, last peak of acoustic emission activity is determined from dependence = f (T), in maximum point of this peak complex parameter K = /2 is calculated, then control samples are loaded to given load and exposed during this load with determining of time till destruction tR, correlation curve "complex parameter K - time till destruction tR" is built, which is used to determine time till destruction of researched material, by measuring same parameters of acoustic emission for it under similar conditions to control samples, during heating of it to same temperature, and by calculating complex parameter K in similar fashion.

EFFECT: higher productiveness.

2 dwg

FIELD: non-destructive testing.

SUBSTANCE: registrar can be used as a part of automated acoustic-emission complex for measuring parameters of acoustic emission. Registrar has digital peak detector which measures pulsation amplitude if resolving level is available which level comes from comparator when pulsation exceeds discrimination voltage specified by reference voltage source. Measured peak voltage is recorded into buffer register and transmitted to computer through communication interface together with data from binary counter which counts number of clock pulses of master oscillator between two close pulsations. Control unit prevents overflow of counter. Control unit initiates arrival of "zero" amplitude pulsation if time interval between pulsations exceeds specified critical value.

EFFECT: widened functional abilities.

1 dwg

FIELD: mechanical engineering.

SUBSTANCE: method comprises recording pulses of acoustic emission, converting the pulses of acoustic emission into a stochastic signal that is composed of the root-mean-square value of the pulses of acoustical emission, and calculating the normalized autocorrelation function from the root-mean-square value. The extent of wear can be judged by the width of the spectral characteristic of the converted signal of acoustic emission.

EFFECT: enhanced quality of monitoring.

FIELD: non-distractive testing.

SUBSTANCE: method comprises using pickups of acoustic emission mounted on the outer surface of the reservoir wall and sealed pickup of acoustic emission that is mounted inside the reservoir to be tested. The submerged pickup of acoustic emission is secured directly to the bottom of the reservoir or is mounted at a distance from the bottom.

EFFECT: enhanced precision.

6 cl, 1 dwg

FIELD: investigating or analyzing materials.

SUBSTANCE: system comprises several measuring lines, each of which is defined by two or more channels interconnected in series for permitting retranslation and retrieving of data transmitted. Each channel consists of the converter of acoustical emission and device for recording and processing the signals of acoustical emission which is mounted directly on the object to be tested. The device for recording and processing the acoustical emission signals comprise power source, preamplifier, main amplifier, and unit for digital processing and transmitting data connected in series.

EFFECT: expanded functional capabilities.

10 cl, 2 dwg

FIELD: prediction of residual resource of equipment.

SUBSTANCE: examination of industrial safety of metal of tested object is performed by spectral analysis method within three most informative frequency ranges: fsd=17,8255881-50,20 Hz; fed=81,67956689-433,89 Hz; fsh-b=1899,668736-2674,25628 Hz. In this case for predicting residual resource and current physical-mechanical parameters the transient factor kρ is used: kρ=[ρ*eq-i-ρ*eq-d]/[ ρ*eq-st-ρ*eq-i], which correctness is provided by weighing of spectral bands by Hamming's window function which allows establishing the following characteristics simultaneously: ρ*eq-st - equivalent standard angle of friction of structural non-uniformities of natural roughness while taking degradation into account at the moment of examination fro one of maximal amplitudes of frequency resonance, which is presented clearly at the general background of standard areas values; ρ*eq-i - equivalent angle of friction of structural non-uniformities during examination while taking degradation of maximal amplitudes of frequency resonance; ρ*eq-d - equivalent angle of friction of structural non-uniformities of natural roughness at the moment of complete degradation.

EFFECT: simplified procedure of degradation; high precision.

3 cl, 3 dwg

FIELD: technology for diagnosing corrosive cracking of material under voltage.

SUBSTANCE: spectrum of acoustic emission pulses is measured in broad frequencies range 0,02-2,0 MHz, analysis of thin structure of acoustic emission pulse spectrums is performed on appearance of two and more characteristic maximums of spectrum amplitudes, at personal computer display acoustic emission process is displayed in discontinuous representation in form of cubic bitmap image, by use of which as a result fractal dependence during destruction process is determined, on basis of time-based alternation of which in steps following are determined: moments of beginning of corrosive cracking, evolution of corrosive cracking, comparison is performed to threshold values of fractal units, appropriate for finalizing stage of corrosive self-destruction of sample.

EFFECT: increased precision of registration of corrosion cracking process.

4 dwg

FIELD: the invention is designed for non-destructive control of durability of products.

SUBSTANCE: the essence is in that in the process of non-destructive control of durability of products the product is evenly or in discrete steps evenly loaded and the number of impulses of acoustic emission and their amplitudes are registered in the processes of loading. At that the summary amplitude ζ of impulses of acoustic emission is additionally determined, the relation of logarithms of the summary amplitudes are determined in specified moments of time ti, tj, the law of distribution of the number of impulses of acoustical emission along the amplitudes is determined with simultaneous determination of nominal voltages σi, σj in the controlled zone of the product in the moments of time ti, tj correspondingly. According to the results of the tests the parameters of condition of the material of the controlled product YAE according to themathematical formula.

EFFECT: increases accuracy of results of acoustic-emissive control of the product, determination of distinct classification of the degree of the danger of sources of impulses of acoustical emission.

FIELD: diagnosis of rail lengths of metal bridge.

SUBSTANCE: method involves continuously measuring longitudinal and transverse deformations of rail and rate of changing longitudinal and transverse deformations, said measurements being performed upon coming of train onto rail; starting acoustic signals receiving and detecting operations when rate of changing longitudinal deformation differs from zero, and ceasing said operations when rate of changing transverse deformation differs from zero; renewing acoustic signal receiving operation when rate of changing transverse deformation is equal to zero and ceasing said operation when rate of changing longitudinal deformation is equal to zero.

EFFECT: provision for obtaining of reliable control results and reduced volume of measurement information.

3 cl, 4 dwg

FIELD: technology for acoustic-emission control and diagnostics of reservoirs for storage of liquefied gas.

SUBSTANCE: in accordance to method, acoustics properties of reservoir are studied, speed of expansion of stress waves, fading degree, type of oscillations, noise level are determined, primary transformers are positioned, using received data, reservoir is loaded, acoustic emission signals are registered before moment of arrival at primary transformer of first false impulse of acoustic emission, acoustic emission signals are processed, while for duration of processing equipment, registering acoustic emission signals, is blocked, and registration is renewed until full fading of oscillations caused by impulse of acoustic emission, on basis of which technical condition of reservoir is evaluated. Time of arrival of first false impulse of acoustic emission at primary transformer and time left until full fading of oscillations in reservoir are determined mathematically on basis of result of research of acoustic properties of reservoir.

EFFECT: increased productiveness and precision when detecting defects during control and diagnostics of technical condition of reservoirs for storage of liquefied gas.

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