Applied Mechanics and Materials Vol. 893

Abstract: Pressure vessels are subjected to repeated loads during use and charging, which can causefine physical damage even in the elastic region. If the load is repeated under stress conditions belowthe yield strength, internal damage accumulates. Fatigue life evaluation of the structure of thepressure vessel using finite element analysis (FEA) is used to evaluate the life cycle of the structuraldesign based on finite element method (FEM) technology. This technique is more advanced thanfatigue life prediction that uses relational equations. This study describes fatigue analysis to predictthe fatigue life of a pressure vessel using stress data obtained from FEA. The life prediction results areuseful for improving the component design at a very early development stage. The fatigue life of thepressure vessel is calculated for each node on the model, and cumulative damage theory is used tocalculate the fatigue life. Then, the fatigue life is calculated from this information using the FEanalysis software ADINA and the fatigue life calculation program WINLIFE.

Abstract: The article deals with the axisymmetric elastoplastic problem for a hollow thick-walled cylinder (plane deformed state), loaded from the inside and outside by uniform pressures proportional to one parameter. The material is considered to be perfectly plastic, with the elastic modulus and yield strength generally are arbitrary functions of the radius. In addition, the material is considered to be incompressible in both plastic and elastic zones. On the basis of the criteria for the plasticity of Huber - Mises and Tresca - Saint-Venant, the radius at which the first plastic deformations occur is determined. It is shown that, depending on the functions of the inhomogeneity of elastic and plastic parameters and loads, the occurrence of plastic deformations is possible both on the surfaces and on the inner walls of the cylinder.

Abstract: Functional Near Infrared Spectroscopy (fNIRS) is a relatively new neuroimagingtechnique adequate and useful for exploring neural activity in social contexts involving humaninteractions. Compared to functional Magnetic Resonance Imaging (fMRI), fNIRS is easy-to-usesafe, noninvasive, silent, relatively low cost and portable, and applicable to subjects of all ages, thusresulting in a good option for ecological studies involving humans in their real-life context.Moreover, by using hyperscanning technique, fNIRS allows recording the hemodynamic cerebralactivity of two interacting subjects in an ecological context or during a shared performance. Thus,moving from a simple analysis about each subject’s neural response during joint actions towardsmore complex computations makes possible to investigate brain synchrony, that is the if and howone’s brain activity is related to that of another interacting partner simultaneously recorded. Here,we discuss how connectivity analyses, with respect to both time and frequency domain procedures,permitted to deepen some aspects of inter-brain synchrony in relation to emotional closeness, and tohighlight how concurrent, cooperative actions can lead to interpersonal synchrony and bondconstruction.

Abstract: Cargo hose tower is an alternative equipment that can be used in loading-unloadingprocess in oil tanker. This paper describes a structural safety analysis of cargo hose tower that transferoil to and from tankers or cargo vessels. Stresses for two types of load conditions that wereconsidered in this study and were drawn by finite element analysis. The results of the finite elementanalysis was also compared with the allowable stresses required in order to determine the designappropriateness of the cargo hose tower structure.

Abstract: Poor heat treatment of the generator may cause cracks during operation. The presence ofcracks on the rotor causes the rotor to vibrate. The paper establishes a finite element modeling of aunit. The model is used to study the vibration response characteristics of the shafting system when thesupport characteristics of the generator are similar and the difference is significant. When thedifference in support characteristics between the two ends of the generator is large, the first-orderunbalance of the generator not only causes a large in-phase vibration at the first-order critical speed ofthe generator, but also causes a large reverse component. Finally, the reliability of the conclusion isfurther verified by combining the abnormal vibration diagnosis and processing cases of a generator.The innovation of the paper is to diagnose the possible cracks in the generator through the vibration ofthe generator, and then look at the original data in the generator manufacturing process to find that theheat treatment process of the generator rotor is poor.

Abstract: Finite element model based on a unit with cracks in the rotor of the exciter is set up. Andthen critical speed is calculated that compared to actual measured value to verify the rationality of themodel. Lastly response characteristics of the three-bearings supporting structure are studied when thefirst critical speed of the exciter with cracks is closed to the working speed. And the reliability ofconclusions is further verified by case analysis.

Abstract: The vibration of a generator in a power plant and the cause of rotor cracking wereanalyzed. The causes of generator rotor cracking were analyzed from the rotor raw material andheat treatment process. The results show that the brittleness and notch sensitivity of the rotormaterial are large due to the unreasonable heat treatment process of the rotor. When the stress isconcentrated, a cracking accident occurs. The generator rotor was returned to the manufacturingcompany for operation. At 3000 r•min-1, the generator's overhanging end vibrated greatly, and thefault was successfully eliminated by the dynamic balance test.

Abstract: During the overhaul of a steam turbine of a power station, the frequency of the last twostages of the low-pressure rotor is tested and high-pressure rotor-regulated stage broken blades weresubjected to macroscopic inspection and analysis, chemical composition analysis, hardness test andmetallographic microstructure observation and analysis.The results of blade frequency measurementshow that the two stages of the low-pressure rotor can be safely and stably operated at the workingspeed. The results of broken blade analysis show that: due to the surface damage in the innersurface of the blade root, the blade vibration is aggravated, and the lower step of the concavegroove of the blade root is the stress concentration zone, where the fatigue crack source is generatedand gradually expanded, resulting in fatigue fracture of the blade; The fracture fatigue source zoneand the fatigue crack growth zone occupy approximately two-thirds of the entire fracture area,indicating that the blade fracture is a high-cycle fatigue fracture.

Abstract: The energy level structure of Yb3+ is analyzed, and a theoretical model is established. Theinfluence of pumping power, fiber length, reflectance of cavity mirror and other related parameters onthe performance of the laser is analyzed. The maximum output power can be achieved at a certainreflectance. The higher the input pump power, the smaller the reflectance of the rear mirror whichobtains the maximum output power. For different pumping wavelengths, the optimal length of thegain fiber is not the same, and it is also different from the optimal length determined by the minimumpumping threshold. Therefore, in the design of fiber lasers, we should consider comprehensively todetermine the appropriate fiber length. Reducing inner raduis is beneficial to improving slopeefficiency when the characteristics of the fiber itself remain unchanged.