Contact Interaction of Steam Turbine Inner Casing Elements During Plastic Deformation

A structure’s material plasticity influence on the pattern of contact interaction of its elements during operation is studied. The stress-strain state problem for the inner casing of a steam turbine high-pressure cylinder operating at supercritical steam parameters (over 240 atm and 565 °C) is solved. The problem is solved by using a finite-element software package. A model of thermoplasticity with kinematic and isotropic hardening is considered. In carrying out the study, experimental strain curves were used for the materials of the connection. The main dependencies used in solving the problem are given. The method of solving the thermal contact problem of interaction of flange connector elements in the conditions of plasticity is based on the application of a contact layer model. To be able to take into account changes in the load from the fastening in the process of combined strain of both the fastening and the casing, first proposed is a method of the three-dimensional modeling of the thermal tightening of the fastening of the horizontal casing connector by applying the linear coefficient of linear expansion of the material. The proposed approach allows modeling the stress of the initial tightening of studs by specifying a fictitious change (decrease) of the coefficient of linear expansion of a stud given as a separate body in the calculation scheme. The magnitude of the specified change in the coefficient of linear expansion is determined from the relationship between the stress of the initial tightening in the stud and the required, for its creation, elongation, which is implemented in the calculation scheme in the presence of different values of linear expansion of both the stud and the casing. To conduct the numerical experiment, an ordered finite-element grid of the casing design was constructed. A 20-node finite element was used in the construction of the casing grid and the fastening. The effect of force loads and the temperature field, in which the structural element under consideration is operated, is taken into account. An analysis of the results of distribution of equivalent stresses and contact pressure during operation is carried out. The difference between the obtained results and the results of solving the problem in the elastic formulation is noted.

Unifying approaches: derivation of Balitsky hierarchy from the Lipatov effective action

We consider a derivation of the hierarchy of correlators of ordered exponentials directly from the Lipatov’s effective action (Lipatov in Nucl Phys B 452:369, 1995; Phys Rep 286:131, 1997; Subnucl Ser 49:131, 2013; Int J Mod Phys Conf Ser 39: 1560082, 2015; Int J Mod Phys A 31(28/29):1645011, 2016; EPJ Web Conf 125: 01010, 2016) formulated in terms of interacting ordered exponentials (Bondarenko and Zubkov in Eur Phys J C 78(8), 617 2018; Bondarenko et al. in Eur Phys J C 81(7):61, 2021). The derivation of the Balitsky equation (Balitsky in Nucl Phys B 463:99, 1996; Phys Rev D 60:014020, 1999; At the frontier of particle physics, vol. 2, p. 1237–1342; Nucl Phys B 629:290, 2002; Phys Rev D 72:074027, 2005) from the hierarchy is discussed as well as the way the sub-leading eikonal corrections to the Balitsky equation arise from the transverse field contribution and sub-leading eikonal corrections to the quark propagator. We outline other possible applications of the proposed calculation scheme.

COMPARISON OF HOP COUNT ON WIRELESS MESH NETWORK

Wireless Mesh Network (MWN) is a self-configured and self-organized network that can typically be implemented on 802.11 hardware. It consists of several nodes that make up the network backbone in a multi-story and sealed room, in contrast to building a hall or a place without bulkheads. This experiment uses an odd and even number scheme with a maximum number of routers of 8 pieces. In a sealed room, the performance of the method of installation of the number of strange Hops is better than the number of even Hops, with throughput calculation of 2665.19 KB, delay 0.25 s, data lost 0.60 %, and jitter 0.01 s and the best scheme that is with the number of Hops as much as five pieces, with the calculation of the number of throughput 7001.88 KB, delay 0.51s, data lost 0.47%, and jitter 0.002 s. In the free spaces, it can produce the better performance of the even hop count calculation scheme than the odd hop count by building throughput 16709.8 KB, delay 0.2 s, data lost 0.08 %, and jitter 0.03 s. and the best scheme that is with the number of throughput 68975,2 KB, wait for 0.0148 s, data lost 0 %, and jitter 0.0014 s. WMN performance in unshared space is more maximized than the version in a sealed area, with throughput values of 11786.82 kbps, delay of 2.08 ms, and data lost by 0.08 %, and jitter 0.03 s.it can produce the better performance of the even hop count calculation scheme than the odd hop count by producing throughput 16709.8 KB, delay 0.2 s, data lost 0.08 %, and jitter 0.03 s. and the best scheme that is with the number of throughput 68975,2 KB, wait for 0.0148 s, data lost 0 %, and jitter 0.0014 s. WMN performance in unshared space is more maximized than the version in sealed space, with throughput values of 11786.82 kbps, delay of 2.08 ms, and data lost by 0.08 %, and jitter 0.03 s. and data lost by 0.08%, and jitter 0.03s.

Identification of Analytical Dependencies of the Operational Characteristics of the Workpiece Clamping Mechanisms with the Rotary Movement of the Input Link

The research is devoted to the problem of determining the efficiency of the workpiece fixing mechanism operation. Improving characteristics of workpiece fixing is one of the required conditions to increase the cutting modes, which may help to enhance the machining productivity. The study investigates the main characteristics and general features of a new structure of clamping mechanisms with electromechanical actuators for fixation of rotation bodies. The main advantages of using electromechanical clamping actuators with self-braking gear are presented. Two simplified dynamical models for the description of different stages of the clamping process are developed. The calculation scheme was formulated to find out how the mass-geometric parameters of mechanism elements should influence the main characteristics of the clamping mechanisms of this type.

GENERAL METHOD FOR CALCULATING BUTT AND ANGLE WELDS FOR STRENGTH

The existing methods for calculating butt and fillet welds are private, developed for specific design solutions that do not take into account the variety of weld shapes and the variety of combinations of forces and moments. The article provides a general method for calculating butt and fillet welds for strength, based on the calculation method for nominal stresses, adopted in the strength of materials. This technique was used without any changes for the calculation of butt welds, since the weld is an extension of the part. The calculation of fillet welds is based on two assumptions, on the basis of which a calculation scheme has been developed, which makes it possible to use the calculation method for rated stresses. The article proposes two design schemes, considers the calculation procedure and derives two generalized strength conditions for the verification calculation of butt and fillet welds.

Calculation scheme of ground freezing depth in Terskol

During the construction of avalanche-retaining geotechnical structures in mountainous areas comes up the problem of fixing and stability of these structures in conditions of seasonal and/or long-term freezing of the ground. This paper evaluates the influence of snow cover and air temperature on the depth of freezing and soil stability based on the developed calculation scheme for the winter seasons 2015/16-2019/20 in the Elbrus region. The calculation scheme was based on the problem of thermal conductivity of a three-layer medium (snow, frozen, and thawed soil) with a phase transition at the boundary. The heat balance equation included the energy of the phase transition, the inflow of heat from the thawed ground and the outflow to the frozen ground, and, in the presence of snow cover, through it to the atmosphere.

NUMERICAL OPTIMIZATION OF A MULTIPHYSICS CALCULATION SCHEME

This work concerns the numerical optimization of a multiphysics calculation scheme. The considered application is a 5x5 Pressurized Water Reactor (PWR) assemblies mini-core surrounded by radial and axial reflectors. The scenario adopted for the analysis is steady-state nominal conditions and fission products set to the equilibrium concentration. The neutronics is modelled at the pin-cell scale and the thermal-hydraulics at the subchannel level. Depending on the scenario, the damped fixed-point algorithm might not be sufficiently robust or efficient enough. For this reason, a technique based on the partial convergence of the solvers is tested. In every multiphysic iteration, a maximum number of iterations is imposed for both the neutronics and the thermal-hydraulics solvers. In combination with that, the solver restarts from the results of the last calculation. In this way, if the method is convergent, the initialization progresses towards the fixed-point solution. The results show that such a technique improves both the robustness and the speed of the algorithm. Within this approach, the range of relaxation factors that makes the algorithm converge is significantly broadened and the importance of this parameter on the global performance is reduced. The computing time also decreases by a factor between 10 and 20. Furthermore, this gain does not strongly depend on the exact imposed maximum number of iterations. Some preliminary observations are also reported in respect with the application of such a technique to the Anderson acceleration method.