Влияние микротрещин на коэффициент Пуассона при пластическом деформировании аустенитной стали

We researched the influence of damage accumulation on the Poisson's ratio measured by echo-pulse acoustic method during plastic deformation of 12Kh18N10T steel. On the basis of the obtained experimental data we calculated the partial contributions to the change in the Poisson's ratio of damage accumulation and separation of the strain induced martensite phase. The characteristics of stable cracks forming near strain martensite particles at small degrees of plastic strain have been analyzed by computer simulation. The theoretical dependence of the change in the Poisson's ratio due to crack formation during plastic deformation has been constructed. A good agreement between the experimental data and theoretical calculations has been obtained.

Analysis of trypsin activity at β-casein layers formed on hydrophobic surfaces using a multiharmonic acoustic method

Proteolysis of milk proteins, such as caseins, caused by milk proteases, can change the organoleptic and nutritional characteristics of milk, and therefore it is essential to monitor this enzymatic activity....

Analysis of methods and methods of diagnosing internal combustion engines by non-assembly control methods

The question of interaction of schemes of diagnostics of engines by methods of non-disassembled control is considered, the analysis of existing methods is executed, and the use of the complex approaches increasing reliability of work of engines is offered. Methods of non-detachable diagnostics with modeling of deregulation of engine systems during operation and diagnosing the initial stages of structural and functional malfunctions are analyzed. The analysis allowed to determine the direct diagnostic parameters that unambiguously characterize the state of the object and indirect, associated with direct functional dependencies, and identify the most effective, in terms of determining correlations - direct diagnostic methods, which include, for example, indication of the working process in the engine cylinder. A relatively simple scheme of measuring and determining signals from several diagnostic elements simultaneously is proposed, from which we can conclude that information from one measurement channel can comprehensively characterize the technical condition of several elements of engine mechanisms or systems: vibration method, acoustic method, gas chromatography methods, indirect indication by determining the stress in the studs of the cylinder head, assessing the level of wear of parts on the metal content in the engine oil, as well as diagnosing the parameters of the uneven speed of the crankshaft. Analysis of methods and techniques for diagnosing internal combustion engines led to the conclusion that the method of diagnosing the uneven speed of the engine crankshaft is a promising direction in the development of methods of non-demountable diagnostics of internal combustion engines. residual life and monitor the technical condition of the engine.

Acoustic methods in real-time welding process monitoring: Application and future potential advancement

The rapid advancement of the welding technology has simultaneously increased the demand for the online monitoring system in order to control the process. Among the methods that could be possibly used to assess the weld condition, an air-borne acoustic method grasps the attention from scholars due to its ability to provide a simple, non-contact, and low-cost measurement system. However, it is still lack of resources involving this subject in an attempt to deeply understand the emitted sound behaviour during welding especially when dealing with a complete deviation of a process parameter, welding types, workpiece material as well as the noise from the surrounding. This paper reviews the application of the acoustic method in monitoring the welding process. Specifically, this review emphasized the source of both structure-borne and air-borne acoustic during the welding process and the significance of applying the acoustic method in more detail. By focusing on the liquid state welding process, the scope of discussion converged on the arc and laser welding process. In the last part of this review, the potential future advancement of this method is pointed out before the overall conclusion is made.

Characteristics of six layered Al/Si3N4 functionally graded materials prepared through two-step pressureless sintering process

The rapid advancement of the welding technology has simultaneously increased the demand for the online monitoring system in order to control the process. Among the methods that could be possibly used to assess the weld condition, an air-borne acoustic method grasps the attention from scholars due to its ability to provide a simple, non-contact, and low-cost measurement system. However, it is still lack of resources involving this subject in an attempt to deeply understand the emitted sound behaviour during welding especially when dealing with a complete deviation of a process parameter, welding types, workpiece material as well as the noise from the surrounding. This paper reviews the application of the acoustic method in monitoring the welding process. Specifically, this review emphasized the source of both structure-borne and air-borne acoustic during the welding process and the significance of applying the acoustic method in more detail. By focusing on the liquid state welding process, the scope of discussion converged on the arc and laser welding process. In the last part of this review, the potential future advancement of this method is pointed out before the overall conclusion is made.

Acoustic Method of Quality Control of Two-Component Composite Materials

The features of using the acoustic method for accurately determining the concentration of components in two-component composite materials by measuring the speed of sound of long waves are described in this paper. Furthermore, explicit expressions for the volume concentrations of the matrix material and reinforcing particles or fibers of composite materials obtained by acoustic measurements are found. In addition, the advantages, features, and limits of the application of acoustic quality control of composite materials of various compositions and purposes are described. It is established that the methods for determining the concentration of components are valid for all types of composite materials, which are conveniently considered as phonon crystals. These results make it possible to more accurately determine or select a measuring cell for the experimental determination of the speed of sound. The mathematical problem to be solved is a purely exact inverse problem.

Analisis Akustik Target Strength Penyu Hijau (Chelonia Mydas) Melalui Pengukuran Secara Terkontrol Pada Frekuensi 200 kHz

ABSTRACT Turtles are reptiles that live in the sea and are able to migrate over long distances along the Indian Ocean, Pacific Ocean and Southeast Asia. Currently the number of turtle populations in nature has greatly decreased. This population decline is caused by natural factors and human activities that endanger the population directly or indirectly. At this time the tagging set technique (ID tag code) is a method that is often used to detect the presence of turtles by attaching tags to female turtles who are landing to lay eggs on the beach or while in captivity or the discovery of the mother turtle by fishermen. One other method that can be used to detect the presence of turtles is to use the acoustic method. The purpose of this study was to analyze the characteristics of the acoustic backscattering energy of the green turtle (Chelonia mydes) and to analyze the relationship between target strength and total body length of the green turtle (Chelonia mydas). This research was conducted in the Tapak Paderi waters pond, Bengkulu City, in August-October 2020. The average target strength (TS) value for green turtles was -48.07 dB. Based on the regression equation, the value of determination (R2) obtained is 0.78. Where this value shows that the total length of the green turtle has an effect of 78% on the average target strength (TS) value, while for 22% it is caused by other factors such as body shape, environmental factors and other factors. Based on the ANOVA test, it can be concluded that there is a relationship between the total length and the value of the target strength (TS) on the green turtle or the value of the total length has an influence on the value of the target strength (TS) on the green turtle.

Studuing and developing methods of propeller shaft technical diagnostics

The propeller shafts are the structural components that require increased attention. The results of studying the damage of propeller shafts are presented in accordance with the safety requirements (a case of the river vessels). It is shown that residual stresses greatly impact the reliability and operability of the shafts becoming a damaging factor. The residual stresses occur due to surfacing the propeller shaft by ST35 steel with SV-08A welding wire. There is considered the possibility of determining the magnitude of residual stresses by the acoustic method in the surfacing. To estimate stresses the phenomenon of acoustoelasticity was used: the dependence of the elastic waves propagation velocity on the magnitude of the acting stresses. The process of determining the acoustoelasticity coefficients was carried out using standard samples (in accordance with GOST1497). Samples modeling surfacing were manufactured and tested. Metallographic studies were carried out to assess the influence of the material composition of the propeller shaft on the structure and strength properties of the propeller shafts. The influence of the structure on the amount of residual stresses was evaluated. It has been inferred from the tests results that the speed of elastic waves depends on the residual stresses. The results of the work can be used in production conditions for the control of products made of 35 steel with surfacing. In conclusion, the proposed method can be used to determine the residual stresses directly on the propeller shafts in operation conditions during the appropriate maintenance of ships.