UNFORMALIZED ASPECTS OF APPLICATION THE NON-DESTRUCTIVE METHODS FOR DETERMINATION OF CONCRETE QUALITY ON ROAD CONCRETE COATINGS

Formulation the problem. Experience with the use of non-destructive testing devices shows that theadjustment of calibration dependences in the conditions of damaged concrete surfaces is difficult. Usually quantitativeanalysis is replaced by qualitative, and methods that allow you to return to the quantitative assessment are notstandardized. That is, the adequacy of property definitions needs to be increased. The purpose of the study is todetermine the possibilities of increasing the adequacy in the using of non-destructive testing devices and to study theinfluence of the peculiarities of the technology of manufacturing concrete pavements on the measurement results.Results: It has been performed a visual inspection of the condition of the coating structure on the basis of currentregulations. The study was performed using an ultrasonic device "Novotest IPSM-U" and a device "Onyx 2.5" (shockpulse method). Measurements were performed both on the surface of the concrete pavement and on the samples takenfrom the structure. During the work, project materials and passports for the concrete mixture were used. Conclusions.Studies have shown that: to obtain evidence-based results in the application of non-destructive methods for determiningthe quality of concrete road pavements, existing methods need to be improved and formalized; it needs to be clarifiedand formalized the methods of providing acoustic contact of receivers − transmitters of ultrasonic vibrations with theconcrete surface and the conditions of interaction the indentors with the concrete surface during the implementation ofthe method of elastic rebound; it is necessary to develop and standartize a method for determining the properties of theconcrete mixture based on the properties of concrete.

PROBLEMS OF HIGH-SPEED RAIL FLAW DETECTION

The main factors that reduce the quality of non-destructive testing of rails during high-speed scanning are considered. The most significant factors are the quality and volume of obtaining primary information about the condition of the monitored rails. It is shown that, at high-speed (up to 120 km/h) control, the compression of the defect location zone is clearly manifested and the length of the areas with acoustic contact violations increases. Analysis of real flaw diagrams of diagnostic complexes shows that with an increase in the scanning speed, the length of the location zone even from such large reflectors in the rails, such as bolt holes, significantly decreases. The average length of the instability zone of the bottom signal over the welded joints of the rails also increases significantly. The compression of the location zones of the reflectors can be compensated by expanding the aperture of the ultrasonic transducers. Improving the quality of the acoustic contact requires further improvement of the design of the search system and the systems for supplying the contacting liquid to the transducers, depending on the scanning speed. The Magnetic Flux Leakage(MFL) method can effectively detect defects in the rail head up to 20 mm deep at high speeds. Mathematical modeling of the magnetic flux in the controlled rails is performed. This allows us to start creating a new rail magnetization system with an increased interpole distance for high speeds. The introduction of modern methods for processing a significant flow of flaw detection information using neural networks requires the formation of a large sample base of training signals from real defects in different sections of rails. This is a complex task in its own right. For the first time, the issues of checking the operability of flaw detection devices in real control conditions are raised. Testing of ultrasonic equipment at high speeds is proposed to be carried out with the help of special electronic-acoustic simulators of defects. They are installed on different surfaces of the rails on which the diagnostic complexes pass. Operational quality control of ultrasonic rail inspection can be evaluated by statistical analysis of signal parameters from structural elements (bolt holes). The choice between the monitoring performance and the required reliability of detecting rail defects must be made based on the results of real passes of diagnostic complexes at operating scanning speeds.

CALCULATION ON THE STRENGTH OF DEFORMING ELEMENTS AND DEVELOPMENT OF FIRMWARE STRUCTURES FOR ULTRASOUND PROCESSING

The possibility of increasing the efficiency and expanding the technological capabilities of the process of deforming drawing, by studying the contact phenomena and force characteristics of the process of deforming drawing (flashing) with the imposition of ultrasonic vibrations on the tool. The main advantages of deforming drawing with application of ultrasound are noted, among which it is necessary to allocate considerable decrease in force parameters of process, reduction of level of residual stresses, increase of accuracy of the processed details. Also, the application of ultrasound allows you to process parts made of metal and alloys, the processing of which in normal conditions is impossible and requires special techniques. It is noted that it is not possible to use known designs of broaches and firmware when flashing with the application of ultrasonic vibrations, because the firmware must have all the dimensions related to the acoustic parameters and the deforming element must be placed on the mandrel with tension to create good acoustic contact between the mandrel and the element. Prefabricated deforming firmware for processing holes with the imposition of longitudinal ultrasonic vibrations has been developed and a method for calculating their deforming elements for strength has been proposed. The performed calculations showed that the calculated stresses differ from the allowable ones by no more than 15-20 %. From the above calculations it is seen that the deforming element can be destroyed, both under the action of the working load in the process of flashing, and under the action of thermal stresses after the exit of the element from the machined hole. This difference in the results of research can be explained by the fact that the order of tensile strength is a value that has a large scattering zone and in different studies it is different. The results of research on the strength of deforming elements can be used in engineering calculations in the design of prefabricated tools for drawing holes with ultrasound.

FRP STRUCTURES RADIUS ZONES ULTRASONIC TESTING (review)

The review of FRP structures radius zones ultrasonic non-destructive testing techniques is given in the paper. It is shown that both single-element piezoelectric transducers and phased arrays can currently be used to solve this problem. It is necessary to use special tools for positioning and creating an acoustic contact with both types of transducers. Ultrasonic testing using the described tools allows detecting defects in radius zones up to 6 mm in size.

Optimization of mechanized ultrasonic testing parameters for extended welds

The requirements for the speed, pitch and scanning direction, and also for ensuring acoustic contact maintenance and taking into account the anisotropy of rolled products during mechanized ultrasonic testing of extended welds of steel structures are formulated based on the research conducted and the analysis of the literature data on the conditions of diagnostics for main pipelines facilities. The relevance of the work is determined by a large amount of welded joints inspection, including butt and longitudinal pipe welds, casings of pig-trap stations, filters of different application purposes, and steel tank wall structures. The article formulates the general principles of choosing mechanized scanning parameters and shows the need to consider ultrasound scattering indicatrix on various defects. The issues of setting the monitoring parameters are considered, including the possibility of using vertical drilling (vertical cylindrical reflector) for the adjustment and check of the equipment during mechanized scanning.

Status of nondestructive control of transport function metal products at JSC EVRAZ NTMK

Achievements in the area of automated ultrasonic control of quality of rails, solid-rolled wheels and tyres, wheels magnetic powder crack detection, carried out at JSC EVRAZ NTMK. The 100% nondestructive control is accomplished by automated control in series at two ultrasonic facilities RWI-01 and four facilities УМКК-1 of magnetic powder control, installed into the exit control line in the wheel-tyre shop. Diagram of location, converters displacement and control operations in the process of control at the facility RWI-01 presented, as well as the structural diagram of the facility УМКК-1. The automated ultrasonic control of rough tyres is made in the tyres control line of the wheel-tyre shop at the facility УКБ-1Д. The facility enables to control internal defects of tyres in radial, axis and circular directions of radiation. Possibilities of the facility УКБ-1Д software were shown. Nondestructive control of railway rails is made at two facilities, comprising the automated control line of the rail and structural shop. The УКР-64Э facility of automated ultrasonic rails control is intended to reveal defects in the area of head, web and middle part of rail foot by pulse echo-method with a immersion acoustic contact. The diagram of rail P65 at the facility УКР-64Э control presented. To reveal defects of the macrostructure in the area of rail head and web by mirror-shadow method, an ultrasonic noncontact electromagnetic-acoustic facility is used. It was noted, that implementation of the 100% nondestructive control into the technology of rolled stuff production enabled to increase the quality of products supplied to customers and to increase their competiveness.

Features of the Heating Process in Ultrasonic Welding of Polycarbonate Products under Independent Pressure

This paper presents a mechanism of formation of a hard-to-weld polycarbonate joint by ultrasonic welding. The method utilizes internal and external friction occurring in the welded joint area on abutting surfaces due to shear vibrations of the end of the upper part relative to the lower part. A layer of the heated welded material is formed, localized by thickness, in which predominant absorption of the ultrasonic vibrations occurs, which allows one to obtain high-quality and durable welded joints without significant deformation due to the concentration of thermal energy in the welding zone. The effect of independent welding pressure on the strength of the welded joint of polycarbonate is considered. A new method of ultrasonic welding under the conditions of independent pressure is proposed. The method consists of dividing the static welding pressure into two components: the pressure of the acoustic contact in the zone of contact of the waveguide with the product, and the welding pressure that compresses the welded products, with the latter component being lower than the former. In order to obtain high-quality welded joints made of polycarbonate and to prevent displacement of the welded edges during the welding process relative to each other, a special preparation of the welded edges is developed, which allows one part to be moved vertically relative to the other during the welding process. It is established that the quality of welding depends on the speed of movement and the angle of cutting the edges.

DETERMINATION OF THE ACTUAL AREA OF DRY ACOUSTIC CONTACT IN THE SYSTEM “TRANSDUCER–PRODUCT” IN LOW-FREQUENCY DEFECTOSCOPY

The conditions for the emission of acoustic energy into the pipeline environment and the reception of reflected signals from inconsistencies in dry acoustic contact cause certain dimensions of the actual contact area between the transducers and the pipe surface. The basic approaches to the determination of the actual area of ​​dry acoustic contact between the surfaces of the piezoelectric transducer and the pipe are formulated under the influence of constant static force of pressing the surfaces in low-frequency flaw detection using ultrasonic directional waves. Expressions have been proposed to determine the area of ​​actual acoustic contact for single and numerical micro projections of the pipe surface. The principle of quality control of balancing of acoustic antenna piezoelectric transducers in modern systems of low-frequency diagnostics of the technical state of longitudinal pipelines by ultrasonic directed waves is described. It is revealed that after correct balancing of all the acoustic antenna piezoelectric transducers, the column image does not appear on the display screen and the mathematical support of the system will automatically collect the technical status of the diagnosed section of the pipeline, the results of which are displayed on the display screen. It is established that the actual area of ​​dry acoustic contact in the "piezoelectric product" system in low-frequency defectoscopy depends on the magnitude of the static force of pressing the surface of the piezoelectric transducer to the surface of the product. It is revealed that the deformation of the micro protrusions of the surface of the product under the action of static clamping force is uneven, which does not allow to fully calculate the actual area of ​​dry contact by mathematical methods. It is shown that in modern systems of low-frequency ultrasonic diagnostics of extended pipelines, directional waves control the quality of dry contact of the surface of the piezoelectric transducer with the surface of the pipe by balancing acoustic antennas with the use of special test programs.